[GitHub] [beam] yeandy commented on a diff in pull request #22250: Rszper run inference docs

[GitBox <gi...@apache.org>]

yeandy commented on code in PR #22250:
URL: https://github.com/apache/beam/pull/22250#discussion_r919947632


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+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.

Review Comment:
   ```suggestion
   The RunInference API can be composed into multi-model pipelines. Multi-model pipelines can be useful for A/B testing, or for building out ensembles that are comprised of models that perform tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
   ```



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website/www/site/content/en/documentation/sdks/python-machine-learning.md:
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@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler

Review Comment:
   ```suggestion
   ### Use a keyed ModelHandler
   ```



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website/www/site/content/en/documentation/sdks/python-machine-learning.md:
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@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.

Review Comment:
   ```suggestion
   To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together, which are then applied with a transformation appropriate for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).

Review Comment:
   Not sure if we want to mentioned that we can deal with keyed values in this section as to why to use RunInference.



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+

Review Comment:
   ```suggestion
   
   ####  Scikit-learn
   
   You need to provide a path, accessible by the pipeline, to a file that contains the pickled Scikit-learn model. To use pre-trained models with the RunInference API and the Scikit-learn framework, complete the following steps:
   
   1. Download the pickled model class and host them in a location that the pipeline can access.
   2. Pass the path of the model to the Sklearn `model_handler` by using the following code: `model_uri=<path_to_pickled_file>` and `model_file_type: <ModelFileType>` (where you can specify ModelFileType.PICKLE or ModelFileType.JOBLIB, depending on how the model was serialized).
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler
+
+If a key is attached to the examples, use the `KeyedModelHandler`:
+
+```
+from apache_beam.ml.inference.base import KeyedModelHandler
+ 
+keyed_model_handler = KeyedModelHandler(PytorchModelHandlerTensor(...))
+ 
+with pipeline as p:
+   data = p | beam.Create([
+      ('img1', np.array[[1,2,3],[4,5,6],...]),
+      ('img2', np.array[[1,2,3],[4,5,6],...]),
+      ('img3', np.array[[1,2,3],[4,5,6],...]),
+   ])
+   predictions = data | RunInference(keyed_model_handler)
+```
+
+### Use the prediction results object
+
+The `PredictionResult` is a `NamedTuple` object that contains both the input and the inferences, named  `example` and  `inference`, respectively. Your pipeline interacts with a `PredictionResult` object in steps after the RunInference transform.
+
+```
+class PostProcessor(beam.DoFn):
+    def process(self, element: Tuple[str, PredictionResult]):
+       key, prediction_result = element
+       inputs = prediction_result.example
+       predictions = prediction_result.inference
+
+       # Post-processing logic
+       result = ...
+
+       yield (key, result)
+
+with pipeline as p:
+    output = (
+        p | 'Read' >> beam.ReadFromSource('a_source') 
+                | 'PyTorchRunInference' >> RunInference(KeyedModelHandler)
+                | 'ProcessOutput' >> beam.ParDo(PostProcessor()))
+```
+
+If you need to use this object explicitly, include the following line in your pipeline to import the object:
+
+```
+from apache_beam.ml.inference.base import PredictionResult
+```
+
+## Run a machine learning pipeline
+
+For detailed instructions explaining how to build and run a pipeline that uses ML models, see the
+[Example RunInference API pipelines](https://github.com/apache/beam/tree/master/sdks/python/apache_beam/examples/inference) on GitHub.
+
+## Troubleshooting
+
+If you run into problems with your pipeline or job, this section lists issues that you might encounter and provides suggestions for how to fix them.
+
+### Prediction results missing
+
+When you use a dictionary of tensors, the output might not include the prediction results. This issue occurs because the RunInference API supports tensors but not dictionaries of tensors. 
+
+Many model inferences return a dictionary with the predictions and additional metadata, for example, `Dict[str, Tensor]`. The RunInference API currently expects outputs to be an `Iterable[Any]`, for example, `Iterable[Tensor]` or `Iterable[Dict[str, Tensor]]`.
+
+When RunInference zips the inputs with the predictions, the predictions iterate over the dictionary keys instead of the batch elements. The result is that the key name is preserved but the prediction tensors are discarded. For more information, see the [Pytorch RunInference PredictionResult is a Dict](https://github.com/apache/beam/issues/22240) issue in the Apache Beam GitHub project.
+
+To work with current RunInference implementation, override the `forward()` function and convert the standard Hugging Face forward output into the appropriate format of `List[Dict[str, torch.Tensor]]`. For more information, see an [example with the batching flag added](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_language_modeling.py#L49).

Review Comment:
   ```suggestion
   You might encounter thy the `PredictionResults` output might not include the correct predictions in the `inferences` field. This issue occurs when you use a model whose inferences return a dictionary that maps key to predictions and additional metadata. An example return type is `Dict[str, Tensor]`.
   
   The RunInference API currently expects outputs to be an `Iterable[Any]`. Example types are `Iterable[Tensor]` or `Iterable[Dict[str, Tensor]]`. When RunInference zips the inputs with the predictions, the predictions iterate over the dictionary keys instead of the batch elements. The result is that the key name is preserved but the prediction tensors are discarded. For more information, see the [Pytorch RunInference PredictionResult is a Dict](https://github.com/apache/beam/issues/22240) issue in the Apache Beam GitHub project.
   
   To work with current RunInference implementation, override the `forward()` function and convert the standard Hugging Face forward output into the appropriate format of `List[Dict[str, torch.Tensor]]`. For more information, see our [HuggingFace language modeling example](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_language_modeling.py#L49).
   ```



##########
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##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:

Review Comment:
   Does "single line" refer to another line in the pipeline? Because it will certainly take more than 1 line to do the imports, set up the handlers, and do other model-related setup.



##########
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##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).

Review Comment:
   Link should be `# Use a key handler`. Though if we apply my suggestion `# Use a keyed ModelHandler`



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:

Review Comment:
   ```suggestion
   To import models, you need to wrap them around a `ModelHandler` object. Add one or more of the following lines of code, depending on the framework and type of data structure that contains the inputs:
   ```



##########
website/www/site/content/en/documentation/sdks/python.md:
##########
@@ -48,6 +48,11 @@ language-specific implementation guidance.
 
 ## Using Beam Python SDK in your ML pipelines
 
+To use the Beam Python SDK with your machine learning pipelines, use the RunInference API for PyTorch and Sklearn models. If using Tensorflow model, you can make use of the library from `tfx_bsl`. Further integrations for TensorFlow are planned.

Review Comment:
   ```suggestion
   To integrate machine learning models into your pipelines for making inferences, use the RunInference API for PyTorch and Scikit-learn models. If you are using TensorFlow models, you can make use of the library from `tfx_bsl`. Further integrations for TensorFlow are planned.
   ```



##########
website/www/site/content/en/documentation/sdks/python.md:
##########
@@ -48,6 +48,11 @@ language-specific implementation guidance.
 
 ## Using Beam Python SDK in your ML pipelines

Review Comment:
   Not sure the best wording here..
   ```suggestion
   ## Making machine learning inferences with Python
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results

Review Comment:
   I don't think we need this `Prediction results` section under `Why use the RunInference API?` since it doesn't explain why one should use RunInference. We talk about it in the next section when explaining how to use the API.



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler
+
+If a key is attached to the examples, use the `KeyedModelHandler`:
+
+```
+from apache_beam.ml.inference.base import KeyedModelHandler
+ 
+keyed_model_handler = KeyedModelHandler(PytorchModelHandlerTensor(...))
+ 
+with pipeline as p:
+   data = p | beam.Create([
+      ('img1', np.array[[1,2,3],[4,5,6],...]),
+      ('img2', np.array[[1,2,3],[4,5,6],...]),
+      ('img3', np.array[[1,2,3],[4,5,6],...]),
+   ])
+   predictions = data | RunInference(keyed_model_handler)
+```
+
+### Use the prediction results object

Review Comment:
   ```suggestion
   ### Use the PredictionResults object
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:

Review Comment:
   ```suggestion
   You need to provide a path, accessible by the pipeline, to a file that contains the model saved weights. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models

Review Comment:
   ```suggestion
   ### Use multiple models
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).

Review Comment:
   ```suggestion
   RunInference takes advantage of existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, to enable users to easily plug in models into their pipelines and enjoy a transform optimized for machine learning inferences.
   
   By leveraging how users can create arbitrarily complex workflow graphs, users can then easily build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.

Review Comment:
   ```suggestion
   2. Pass the path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+

Review Comment:
   ```suggestion
   #### PyTorch
   ```



##########
website/www/site/content/en/documentation/sdks/python.md:
##########
@@ -48,6 +48,11 @@ language-specific implementation guidance.
 
 ## Using Beam Python SDK in your ML pipelines
 
+To use the Beam Python SDK with your machine learning pipelines, use the RunInference API for PyTorch and Sklearn models. If using Tensorflow model, you can make use of the library from `tfx_bsl`. Further integrations for TensorFlow are planned.

Review Comment:
   Here's the link to the tfx_bsl repo: https://github.com/tensorflow/tfx-bsl/tree/master/tfx_bsl/beam. Should we add a link?
   
   Here's the issue for the TF work https://github.com/apache/beam/issues/21442. Should we add this link?
   
   



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler
+
+If a key is attached to the examples, use the `KeyedModelHandler`:
+
+```
+from apache_beam.ml.inference.base import KeyedModelHandler
+ 
+keyed_model_handler = KeyedModelHandler(PytorchModelHandlerTensor(...))
+ 
+with pipeline as p:
+   data = p | beam.Create([
+      ('img1', np.array[[1,2,3],[4,5,6],...]),
+      ('img2', np.array[[1,2,3],[4,5,6],...]),
+      ('img3', np.array[[1,2,3],[4,5,6],...]),
+   ])
+   predictions = data | RunInference(keyed_model_handler)
+```
+
+### Use the prediction results object
+
+The `PredictionResult` is a `NamedTuple` object that contains both the input and the inferences, named  `example` and  `inference`, respectively. Your pipeline interacts with a `PredictionResult` object in steps after the RunInference transform.
+
+```
+class PostProcessor(beam.DoFn):
+    def process(self, element: Tuple[str, PredictionResult]):
+       key, prediction_result = element
+       inputs = prediction_result.example
+       predictions = prediction_result.inference
+
+       # Post-processing logic
+       result = ...
+
+       yield (key, result)
+
+with pipeline as p:
+    output = (
+        p | 'Read' >> beam.ReadFromSource('a_source') 
+                | 'PyTorchRunInference' >> RunInference(KeyedModelHandler)
+                | 'ProcessOutput' >> beam.ParDo(PostProcessor()))
+```
+
+If you need to use this object explicitly, include the following line in your pipeline to import the object:
+
+```
+from apache_beam.ml.inference.base import PredictionResult
+```
+
+## Run a machine learning pipeline
+
+For detailed instructions explaining how to build and run a pipeline that uses ML models, see the
+[Example RunInference API pipelines](https://github.com/apache/beam/tree/master/sdks/python/apache_beam/examples/inference) on GitHub.
+
+## Troubleshooting
+
+If you run into problems with your pipeline or job, this section lists issues that you might encounter and provides suggestions for how to fix them.
+
+### Prediction results missing
+
+When you use a dictionary of tensors, the output might not include the prediction results. This issue occurs because the RunInference API supports tensors but not dictionaries of tensors. 
+
+Many model inferences return a dictionary with the predictions and additional metadata, for example, `Dict[str, Tensor]`. The RunInference API currently expects outputs to be an `Iterable[Any]`, for example, `Iterable[Tensor]` or `Iterable[Dict[str, Tensor]]`.
+
+When RunInference zips the inputs with the predictions, the predictions iterate over the dictionary keys instead of the batch elements. The result is that the key name is preserved but the prediction tensors are discarded. For more information, see the [Pytorch RunInference PredictionResult is a Dict](https://github.com/apache/beam/issues/22240) issue in the Apache Beam GitHub project.
+
+To work with current RunInference implementation, override the `forward()` function and convert the standard Hugging Face forward output into the appropriate format of `List[Dict[str, torch.Tensor]]`. For more information, see an [example with the batching flag added](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_language_modeling.py#L49).
+
+### Unable to batch tensor elements
+
+RunInference uses dynamic batching. However, the RunInference API cannot batch tensor elements of different sizes, because `torch.stack()` expects tensors of the same length. If you provide images of different sizes or word embeddings of different lengths, errors might occur.
+
+To avoid this issue:
+
+1. Either use elements that have the same size, or resize image inputs and word embeddings to make them 
+the same size. Depending on the language model and encoding technique, this option might not be available. 

Review Comment:
   ```suggestion
   1. Use elements that have the same size. For CV applications, you would need to resize the images to the same dimensions. For NLP applications, you would need to resize text or word embeddings to the same length. This, however, might not be feasible with texts of varying lengths.
   ```



##########
website/www/site/content/en/documentation/transforms/python/elementwise/runinference.md:
##########
@@ -0,0 +1,94 @@
+---
+title: "RunInference"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# RunInference
+
+{{< localstorage language language-py >}}
+
+{{< button-pydoc path="apache_beam.ml.inference" class="RunInference" >}}
+
+Uses models to do local and remote inference. A `RunInference` transform uses a `PCollection` of examples to create a machine learning (ML) model. The transform outputs a `PCollection` that contains the input examples and output predictions.
+
+You must have Apache Beam 2.40.0 or later installed to run these pipelines.
+
+See more [RunInference API pipeline examples](https://github.com/apache/beam/tree/master/sdks/python/apache_beam/examples/inference).
+
+## PyTorch dependencies
+
+The RunInference API supports the PyTorch framework. To use PyTorch locally, first install `torch`. To install `torch`, in your terminal, run the following command:
+
+`pip install torch==1.10.0`
+
+If you are using pretrained models from Pytorch's `torchvision.models` [subpackage](https://pytorch.org/vision/0.12/models.html#models-and-pre-trained-weights), you also need to install `torchvision`. To install `torchvision`, in your terminal, run the following command:
+
+`pip install torchvision`
+
+If you are using pretrained models from Hugging Face's [`transformers` package](https://huggingface.co/docs/transformers/index), you need to install `transformers`. To install `transformers`, in your terminal, run the following command:
+
+`pip install transformers`
+
+For information about installing the `torch` dependency on a distributed runner such as Dataflow, see the [PyPI dependency instructions](/documentation/sdks/python-pipeline-dependencies/#pypi-dependencies).

Review Comment:
   Can probably be removed if we replace examples with the simpler ones from Anand's notebook



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler
+
+If a key is attached to the examples, use the `KeyedModelHandler`:
+
+```
+from apache_beam.ml.inference.base import KeyedModelHandler
+ 
+keyed_model_handler = KeyedModelHandler(PytorchModelHandlerTensor(...))
+ 
+with pipeline as p:
+   data = p | beam.Create([
+      ('img1', np.array[[1,2,3],[4,5,6],...]),
+      ('img2', np.array[[1,2,3],[4,5,6],...]),
+      ('img3', np.array[[1,2,3],[4,5,6],...]),
+   ])
+   predictions = data | RunInference(keyed_model_handler)
+```
+
+### Use the prediction results object
+
+The `PredictionResult` is a `NamedTuple` object that contains both the input and the inferences, named  `example` and  `inference`, respectively. Your pipeline interacts with a `PredictionResult` object in steps after the RunInference transform.
+
+```
+class PostProcessor(beam.DoFn):
+    def process(self, element: Tuple[str, PredictionResult]):
+       key, prediction_result = element
+       inputs = prediction_result.example
+       predictions = prediction_result.inference
+
+       # Post-processing logic
+       result = ...
+
+       yield (key, result)
+
+with pipeline as p:
+    output = (
+        p | 'Read' >> beam.ReadFromSource('a_source') 
+                | 'PyTorchRunInference' >> RunInference(KeyedModelHandler)
+                | 'ProcessOutput' >> beam.ParDo(PostProcessor()))
+```
+
+If you need to use this object explicitly, include the following line in your pipeline to import the object:
+
+```
+from apache_beam.ml.inference.base import PredictionResult
+```
+
+## Run a machine learning pipeline
+
+For detailed instructions explaining how to build and run a pipeline that uses ML models, see the
+[Example RunInference API pipelines](https://github.com/apache/beam/tree/master/sdks/python/apache_beam/examples/inference) on GitHub.
+
+## Troubleshooting
+
+If you run into problems with your pipeline or job, this section lists issues that you might encounter and provides suggestions for how to fix them.
+
+### Prediction results missing
+
+When you use a dictionary of tensors, the output might not include the prediction results. This issue occurs because the RunInference API supports tensors but not dictionaries of tensors. 
+
+Many model inferences return a dictionary with the predictions and additional metadata, for example, `Dict[str, Tensor]`. The RunInference API currently expects outputs to be an `Iterable[Any]`, for example, `Iterable[Tensor]` or `Iterable[Dict[str, Tensor]]`.
+
+When RunInference zips the inputs with the predictions, the predictions iterate over the dictionary keys instead of the batch elements. The result is that the key name is preserved but the prediction tensors are discarded. For more information, see the [Pytorch RunInference PredictionResult is a Dict](https://github.com/apache/beam/issues/22240) issue in the Apache Beam GitHub project.
+
+To work with current RunInference implementation, override the `forward()` function and convert the standard Hugging Face forward output into the appropriate format of `List[Dict[str, torch.Tensor]]`. For more information, see an [example with the batching flag added](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_language_modeling.py#L49).
+
+### Unable to batch tensor elements
+
+RunInference uses dynamic batching. However, the RunInference API cannot batch tensor elements of different sizes, because `torch.stack()` expects tensors of the same length. If you provide images of different sizes or word embeddings of different lengths, errors might occur.
+
+To avoid this issue:

Review Comment:
   ```suggestion
   There are two solutions to avoid this issue:
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler
+
+If a key is attached to the examples, use the `KeyedModelHandler`:
+
+```
+from apache_beam.ml.inference.base import KeyedModelHandler
+ 
+keyed_model_handler = KeyedModelHandler(PytorchModelHandlerTensor(...))
+ 
+with pipeline as p:
+   data = p | beam.Create([
+      ('img1', np.array[[1,2,3],[4,5,6],...]),
+      ('img2', np.array[[1,2,3],[4,5,6],...]),
+      ('img3', np.array[[1,2,3],[4,5,6],...]),
+   ])
+   predictions = data | RunInference(keyed_model_handler)
+```
+
+### Use the prediction results object
+
+The `PredictionResult` is a `NamedTuple` object that contains both the input and the inferences, named  `example` and  `inference`, respectively. Your pipeline interacts with a `PredictionResult` object in steps after the RunInference transform.
+
+```
+class PostProcessor(beam.DoFn):
+    def process(self, element: Tuple[str, PredictionResult]):
+       key, prediction_result = element
+       inputs = prediction_result.example
+       predictions = prediction_result.inference
+
+       # Post-processing logic
+       result = ...
+
+       yield (key, result)
+
+with pipeline as p:
+    output = (
+        p | 'Read' >> beam.ReadFromSource('a_source') 
+                | 'PyTorchRunInference' >> RunInference(KeyedModelHandler)
+                | 'ProcessOutput' >> beam.ParDo(PostProcessor()))
+```
+
+If you need to use this object explicitly, include the following line in your pipeline to import the object:
+
+```
+from apache_beam.ml.inference.base import PredictionResult
+```
+
+## Run a machine learning pipeline
+
+For detailed instructions explaining how to build and run a pipeline that uses ML models, see the
+[Example RunInference API pipelines](https://github.com/apache/beam/tree/master/sdks/python/apache_beam/examples/inference) on GitHub.
+
+## Troubleshooting
+
+If you run into problems with your pipeline or job, this section lists issues that you might encounter and provides suggestions for how to fix them.
+
+### Prediction results missing

Review Comment:
   ```suggestion
   ### Incorrect inferences in the PredictionResult object
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.
+
+### Prediction results
+
+When doing a prediction in Apache Beam, the output `PCollection` includes both the keys of the input examples and the inferences. Including both these items in the output allows you to find the input that determined the predictions without returning the full input data.
+
+For more information, see the [`PredictionResult` documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L65). 
+
+## Modify a pipeline to use an ML model
+
+To use the RunInference transform, you add a single line of code in your pipeline:
+
+```
+from apache_beam.ml.inference.base import RunInference
+ 
+with pipeline as p:
+   predictions = ( p | beam.ReadFromSource('a_source')   
+    | RunInference(configuration)))
+```
+
+To import models, you need to wrap them around a `ModelHandler object`. Add one or more of the following lines of code, depending on the framework and type of data structure that holds the data:
+
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerNumpy
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerTensor
+```
+```
+from apache_beam.ml.inference.pytorch_inference import SklearnModelHandlerPandas
+```
+```
+from apache_beam.ml.inference.pytorch_inference import PytorchModelHandlerKeyedTensor
+```
+### Use pre-trained models
+
+You need to provide a path to the model weights that's accessible by the pipeline. To use pre-trained models with the RunInference API and the PyTorch framework, complete the following steps:
+
+1. Download the pre-trained weights and host them in a location that the pipeline can access.
+2. Pass the hosted path of the model to the PyTorch `model_handler` by using the following code: `state_dict_path=<path_to_weights>`.
+
+### Use multiple inference models
+
+You can also use the RunInference transform to add multiple inference models to your pipeline.
+
+#### A/B Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = data | RunInference(ModelHandlerB)
+```
+
+#### Ensemble Pattern
+
+```
+with pipeline as p:
+   data = p | 'Read' >> beam.ReadFromSource('a_source') 
+   model_a_predictions = data | RunInference(ModelHandlerA)
+   model_b_predictions = model_a_predictions | beam.Map(some_post_processing) | RunInference(ModelHandlerB)
+```
+
+### Use a key handler
+
+If a key is attached to the examples, use the `KeyedModelHandler`:
+
+```
+from apache_beam.ml.inference.base import KeyedModelHandler
+ 
+keyed_model_handler = KeyedModelHandler(PytorchModelHandlerTensor(...))
+ 
+with pipeline as p:
+   data = p | beam.Create([
+      ('img1', np.array[[1,2,3],[4,5,6],...]),
+      ('img2', np.array[[1,2,3],[4,5,6],...]),
+      ('img3', np.array[[1,2,3],[4,5,6],...]),
+   ])
+   predictions = data | RunInference(keyed_model_handler)
+```
+
+### Use the prediction results object
+
+The `PredictionResult` is a `NamedTuple` object that contains both the input and the inferences, named  `example` and  `inference`, respectively. Your pipeline interacts with a `PredictionResult` object in steps after the RunInference transform.
+
+```
+class PostProcessor(beam.DoFn):
+    def process(self, element: Tuple[str, PredictionResult]):
+       key, prediction_result = element
+       inputs = prediction_result.example
+       predictions = prediction_result.inference
+
+       # Post-processing logic
+       result = ...
+
+       yield (key, result)
+
+with pipeline as p:
+    output = (
+        p | 'Read' >> beam.ReadFromSource('a_source') 
+                | 'PyTorchRunInference' >> RunInference(KeyedModelHandler)
+                | 'ProcessOutput' >> beam.ParDo(PostProcessor()))
+```
+
+If you need to use this object explicitly, include the following line in your pipeline to import the object:
+
+```
+from apache_beam.ml.inference.base import PredictionResult
+```
+
+## Run a machine learning pipeline
+
+For detailed instructions explaining how to build and run a pipeline that uses ML models, see the
+[Example RunInference API pipelines](https://github.com/apache/beam/tree/master/sdks/python/apache_beam/examples/inference) on GitHub.
+
+## Troubleshooting
+
+If you run into problems with your pipeline or job, this section lists issues that you might encounter and provides suggestions for how to fix them.
+
+### Prediction results missing
+
+When you use a dictionary of tensors, the output might not include the prediction results. This issue occurs because the RunInference API supports tensors but not dictionaries of tensors. 
+
+Many model inferences return a dictionary with the predictions and additional metadata, for example, `Dict[str, Tensor]`. The RunInference API currently expects outputs to be an `Iterable[Any]`, for example, `Iterable[Tensor]` or `Iterable[Dict[str, Tensor]]`.
+
+When RunInference zips the inputs with the predictions, the predictions iterate over the dictionary keys instead of the batch elements. The result is that the key name is preserved but the prediction tensors are discarded. For more information, see the [Pytorch RunInference PredictionResult is a Dict](https://github.com/apache/beam/issues/22240) issue in the Apache Beam GitHub project.
+
+To work with current RunInference implementation, override the `forward()` function and convert the standard Hugging Face forward output into the appropriate format of `List[Dict[str, torch.Tensor]]`. For more information, see an [example with the batching flag added](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_language_modeling.py#L49).
+
+### Unable to batch tensor elements
+
+RunInference uses dynamic batching. However, the RunInference API cannot batch tensor elements of different sizes, because `torch.stack()` expects tensors of the same length. If you provide images of different sizes or word embeddings of different lengths, errors might occur.
+
+To avoid this issue:
+
+1. Either use elements that have the same size, or resize image inputs and word embeddings to make them 
+the same size. Depending on the language model and encoding technique, this option might not be available. 

Review Comment:
   ```suggestion
   the same size. For NLP use cases, this might not be possible to do with text of varying lengths.
   ```



##########
website/www/site/content/en/documentation/sdks/python-machine-learning.md:
##########
@@ -0,0 +1,186 @@
+---
+type: languages
+title: "Apache Beam Python Machine Learning"
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Machine Learning
+
+You can use Apache Beam with the RunInference API to use machine learning (ML) models to do local and remote inference with batch and streaming pipelines. Starting with Apache Beam 2.40.0, PyTorch and Scikit-learn frameworks are supported. You can create multiple types of transforms using the RunInference API: the API takes multiple types of setup parameters from model handlers, and the parameter type determines the model implementation.
+
+## Why use the RunInference API?
+
+RunInference leverages existing Apache Beam concepts, such as the the `BatchElements` transform and the `Shared` class, and it allows you to build multi-model pipelines. In addition, the RunInference API has built in capabilities for dealing with [keyed values](#use-the-prediction-results-object).
+
+### BatchElements PTransform
+
+To take advantage of the optimizations of vectorized inference that many models implement, we added the `BatchElements` transform as an intermediate step before making the prediction for the model. This transform batches elements together. The resulting batch is used to make the appropriate transformation for the particular framework of RunInference. For example, for numpy `ndarrays`, we call `numpy.stack()`,  and for torch `Tensor` elements, we call `torch.stack()`.
+
+To customize the settings for `beam.BatchElements`, in `ModelHandler`, override the `batch_elements_kwargs` function. For example, use `min_batch_size` to set the lowest number of elements per batch or `max_batch_size` to set the highest number of elements per batch.
+
+For more information, see the [`BatchElements` transform documentation](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.BatchElements).
+
+### Shared helper class
+
+Instead of loading a model for each thread in the process, we use the `Shared` class, which allows us to load one model that is shared across all threads of each worker in a DoFn. For more information, see the
+[`Shared` class documentation](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/utils/shared.py#L20).
+
+### Multi-model pipelines
+
+The RunInference API can be composed into multi-model pipelines. Multi-model pipelines are useful for A/B testing and for building out ensembles for tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution, and more.

Review Comment:
   The examples here `tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, language detection, coreference resolution` are highly NLP specific. Would it be better to generalize?



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