[GitHub] [arrow] edponce commented on a change in pull request #12460: ARROW-13530: [C++] Implement cumulative sum compute function

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

edponce commented on a change in pull request #12460:
URL: https://github.com/apache/arrow/pull/12460#discussion_r818175519



##########
File path: cpp/src/arrow/compute/kernels/scalar_cumulative_sum.cc
##########
@@ -0,0 +1,147 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#include "arrow/array/array_base.h"
+#include "arrow/compute/kernels/common.h"
+#include "arrow/result.h"
+#include "arrow/visit_type_inline.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+namespace {
+
+template <typename CType>
+CType CumulativeSum(std::shared_ptr<Array>& input, ArrayData* output, CType start) {
+  CType sum = start;
+  CType* data = checked_cast<CType*>(input->data()->buffers[1]->data());
+  CType* out_values = checked_cast<CType*>(output->buffers[1]->mutable_data());
+  for (size_t i = input->offset; i < input->length; ++i) {
+    if (input->IsValid(i)) {
+      sum += data[i];
+      out_values[i] = sum;
+    }
+  }
+
+  return sum;
+}
+
+template <typename Type>
+struct CumulativeSumFunctor {
+  using CType = TypeTraits<Type>::CType;
+
+  Status Exec(KernelContext* ctx, const ExecBatch& batch, Datum* out) {
+    const NumericScalar& start_scalar =
+        checked_cast<const NumericScalar&>(*batch[1].scalar());
+    CType start = start_scalar.value;
+
+    switch (batch[0].kind()) {
+      case Datum::ARRAY:
+        std::shared_ptr<Array> input = batch[0].make_array();
+        ArrayData* output = out->array().get();
+
+        output->length = input->data()->length;
+        *output->type = std::move(input->type());
+        uint8_t* out_bitmap = output->buffers[0]->mutable_data();
+        int64_t out_offset = input->offset();
+
+        if (input->data()->MayHaveNulls()) {
+          arrow::internal::CopyBitmap(input->null_bitmap_data(), input->offset(),
+                                      input->length(), out_bitmap, out_offset);
+          output->null_count = input->null_count();
+        } else {
+          bit_util::SetBitsTo(out_bitmap, out_offset, input->length(), true);
+          output->null_count = 0;
+        }
+
+        CumulativeSum(input, output, start);
+        return Status::OK();
+      case Datum::CHUNKED_ARRAY:
+        const auto& input = batch[0].chunked_array();
+
+        ArrayVector out_chunks;
+        for (const auto& chunk : input->chunks()) {
+          auto out_chunk = std::make_shared<ArrayData>(
+              chunk->type(), chunk->length(), chunk->null_count(), chunk->offset());
+
+          uint8_t* out_chunk_bitmap = out_chunk->buffers[0]->mutable_data();
+          if (chunk->data()->MayHaveNulls()) {
+            arrow::internal::CopyBitmap(chunk->null_bitmap_data(), chunk->offset(),
+                                        chunk->length(), out_chunk_bitmap,
+                                        out_chunk->offset());
+            out_chunk->null_count = chunk->null_count();
+          } else {
+            bit_util::SetBitsTo(out_chunk_bitmap, out_chunk->offset(), chunk->length(),
+                                true);
+            out_chunk->null_count = 0;
+          }
+
+          CType last_value = CumulativeSum(chunk, out_chunk, start);
+          start = last_value;
+          out_chunks.push_back(MakeArray(std::move(out_chunk)));
+        }
+
+        *out->chunked_array() = ChunkedArray(out_chunks, input->type());
+        return Status::OK();
+      default:
+        return Status::NotImplemented(
+            "Unsupported input type for function 'cumulative_sum': ",
+            batch[0].ToString());
+    }
+  }
+
+  static std::shared_ptr<KernelSignature> GetSignature(detail::GetTypeId get_id) {
+    return KernelSignature::Make(
+        {InputType::Array(get_id.id), InputType::Scalar(get_id.id)},
+        OutputType(FirstType));
+  }
+};
+
+const FunctionDoc cumulative_sum_doc(
+    "Compute the cumulative sum over an array of numbers",
+    ("`values` must be an array of numeric type values.\n"
+     "`start` is a single value of the same type.\n"
+     "Return an array which is the cumulative sum computed over `values`\n"
+     "`start` is an optional starting sum of computation."),
+    {"values", "start"});
+
+void RegisterVectorCumulativeSum(FunctionRegistry* registry) {
+  auto add_kernel = [&](detail::GetTypeId get_id, ArrayKernelExec exec,
+                        std::shared_ptr<ScalarFunction> func) {
+    ScalarKernel kernel;
+    kernel.mem_allocation = MemAllocation::type::PREALLOCATE;
+    kernel.signature = CumulativeSumFunctor<NumberType>::GetSignature(get_id.id);
+    kernel.exec = std::move(exec);
+    DCHECK_OK(func->AddKernel(std::move(kernel)));
+  };
+
+  auto cumulative_sum = std::make_shared<ScalarFunction>(
+      "cumulative_sum", Arity::Binary(), &cumulative_sum_doc);
+
+  for (auto ty : NumericTypes()) {
+    add_kernel(ty, GenerateTypeAgnosticPrimitive<CumulativeSumFunctor>(ty),

Review comment:
       We can also sum types that use a physical integer representation (e.g, Duration, Timestamp, etc.)

##########
File path: cpp/src/arrow/compute/kernels/scalar_cumulative_sum.cc
##########
@@ -0,0 +1,147 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#include "arrow/array/array_base.h"
+#include "arrow/compute/kernels/common.h"
+#include "arrow/result.h"
+#include "arrow/visit_type_inline.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+namespace {
+
+template <typename CType>
+CType CumulativeSum(std::shared_ptr<Array>& input, ArrayData* output, CType start) {
+  CType sum = start;
+  CType* data = checked_cast<CType*>(input->data()->buffers[1]->data());
+  CType* out_values = checked_cast<CType*>(output->buffers[1]->mutable_data());
+  for (size_t i = input->offset; i < input->length; ++i) {
+    if (input->IsValid(i)) {
+      sum += data[i];
+      out_values[i] = sum;
+    }
+  }
+
+  return sum;
+}
+
+template <typename Type>
+struct CumulativeSumFunctor {
+  using CType = TypeTraits<Type>::CType;
+
+  Status Exec(KernelContext* ctx, const ExecBatch& batch, Datum* out) {
+    const NumericScalar& start_scalar =
+        checked_cast<const NumericScalar&>(*batch[1].scalar());
+    CType start = start_scalar.value;

Review comment:
       I think the `start` argument could have a default value of 0 instead of being a mandatory argument. For this to work, then `start` would be a `FunctionOption` and this kernel would be unary.

##########
File path: cpp/src/arrow/compute/kernels/scalar_cumulative_sum.cc
##########
@@ -0,0 +1,147 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#include "arrow/array/array_base.h"
+#include "arrow/compute/kernels/common.h"
+#include "arrow/result.h"
+#include "arrow/visit_type_inline.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+namespace {
+
+template <typename CType>
+CType CumulativeSum(std::shared_ptr<Array>& input, ArrayData* output, CType start) {
+  CType sum = start;
+  CType* data = checked_cast<CType*>(input->data()->buffers[1]->data());
+  CType* out_values = checked_cast<CType*>(output->buffers[1]->mutable_data());
+  for (size_t i = input->offset; i < input->length; ++i) {
+    if (input->IsValid(i)) {
+      sum += data[i];
+      out_values[i] = sum;
+    }
+  }
+
+  return sum;
+}
+
+template <typename Type>
+struct CumulativeSumFunctor {
+  using CType = TypeTraits<Type>::CType;
+
+  Status Exec(KernelContext* ctx, const ExecBatch& batch, Datum* out) {
+    const NumericScalar& start_scalar =
+        checked_cast<const NumericScalar&>(*batch[1].scalar());
+    CType start = start_scalar.value;
+
+    switch (batch[0].kind()) {
+      case Datum::ARRAY:
+        std::shared_ptr<Array> input = batch[0].make_array();
+        ArrayData* output = out->array().get();
+
+        output->length = input->data()->length;
+        *output->type = std::move(input->type());
+        uint8_t* out_bitmap = output->buffers[0]->mutable_data();
+        int64_t out_offset = input->offset();
+
+        if (input->data()->MayHaveNulls()) {
+          arrow::internal::CopyBitmap(input->null_bitmap_data(), input->offset(),
+                                      input->length(), out_bitmap, out_offset);
+          output->null_count = input->null_count();
+        } else {
+          bit_util::SetBitsTo(out_bitmap, out_offset, input->length(), true);
+          output->null_count = 0;
+        }
+
+        CumulativeSum(input, output, start);
+        return Status::OK();
+      case Datum::CHUNKED_ARRAY:
+        const auto& input = batch[0].chunked_array();
+
+        ArrayVector out_chunks;
+        for (const auto& chunk : input->chunks()) {
+          auto out_chunk = std::make_shared<ArrayData>(
+              chunk->type(), chunk->length(), chunk->null_count(), chunk->offset());
+
+          uint8_t* out_chunk_bitmap = out_chunk->buffers[0]->mutable_data();
+          if (chunk->data()->MayHaveNulls()) {
+            arrow::internal::CopyBitmap(chunk->null_bitmap_data(), chunk->offset(),
+                                        chunk->length(), out_chunk_bitmap,
+                                        out_chunk->offset());
+            out_chunk->null_count = chunk->null_count();
+          } else {
+            bit_util::SetBitsTo(out_chunk_bitmap, out_chunk->offset(), chunk->length(),
+                                true);
+            out_chunk->null_count = 0;
+          }
+
+          CType last_value = CumulativeSum(chunk, out_chunk, start);
+          start = last_value;
+          out_chunks.push_back(MakeArray(std::move(out_chunk)));
+        }
+
+        *out->chunked_array() = ChunkedArray(out_chunks, input->type());
+        return Status::OK();
+      default:
+        return Status::NotImplemented(
+            "Unsupported input type for function 'cumulative_sum': ",
+            batch[0].ToString());
+    }
+  }
+
+  static std::shared_ptr<KernelSignature> GetSignature(detail::GetTypeId get_id) {
+    return KernelSignature::Make(
+        {InputType::Array(get_id.id), InputType::Scalar(get_id.id)},
+        OutputType(FirstType));
+  }
+};
+
+const FunctionDoc cumulative_sum_doc(
+    "Compute the cumulative sum over an array of numbers",
+    ("`values` must be an array of numeric type values.\n"
+     "`start` is a single value of the same type.\n"
+     "Return an array which is the cumulative sum computed over `values`\n"
+     "`start` is an optional starting sum of computation."),
+    {"values", "start"});

Review comment:
       Also, include a statement of how null values are handled.

##########
File path: cpp/src/arrow/compute/kernels/scalar_cumulative_sum.cc
##########
@@ -0,0 +1,147 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#include "arrow/array/array_base.h"
+#include "arrow/compute/kernels/common.h"
+#include "arrow/result.h"
+#include "arrow/visit_type_inline.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+namespace {
+
+template <typename CType>
+CType CumulativeSum(std::shared_ptr<Array>& input, ArrayData* output, CType start) {
+  CType sum = start;
+  CType* data = checked_cast<CType*>(input->data()->buffers[1]->data());
+  CType* out_values = checked_cast<CType*>(output->buffers[1]->mutable_data());
+  for (size_t i = input->offset; i < input->length; ++i) {
+    if (input->IsValid(i)) {
+      sum += data[i];
+      out_values[i] = sum;
+    }
+  }
+
+  return sum;
+}
+
+template <typename Type>
+struct CumulativeSumFunctor {
+  using CType = TypeTraits<Type>::CType;
+
+  Status Exec(KernelContext* ctx, const ExecBatch& batch, Datum* out) {
+    const NumericScalar& start_scalar =
+        checked_cast<const NumericScalar&>(*batch[1].scalar());
+    CType start = start_scalar.value;
+
+    switch (batch[0].kind()) {
+      case Datum::ARRAY:
+        std::shared_ptr<Array> input = batch[0].make_array();
+        ArrayData* output = out->array().get();
+
+        output->length = input->data()->length;
+        *output->type = std::move(input->type());
+        uint8_t* out_bitmap = output->buffers[0]->mutable_data();

Review comment:
       bitmap can be nullptr

##########
File path: cpp/src/arrow/compute/kernels/scalar_cumulative_sum.cc
##########
@@ -0,0 +1,147 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#include "arrow/array/array_base.h"
+#include "arrow/compute/kernels/common.h"
+#include "arrow/result.h"
+#include "arrow/visit_type_inline.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+namespace {
+
+template <typename CType>
+CType CumulativeSum(std::shared_ptr<Array>& input, ArrayData* output, CType start) {

Review comment:
       This can be included as a method of `CumulativeSumFunctor` as `Sum`. Any particular reason why it stands alone?
   
   I suggest renaming `CumulativeSumFunctor` to `CumulativeSum`.

##########
File path: cpp/src/arrow/compute/kernels/scalar_cumulative_sum.cc
##########
@@ -0,0 +1,147 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#include "arrow/array/array_base.h"
+#include "arrow/compute/kernels/common.h"
+#include "arrow/result.h"
+#include "arrow/visit_type_inline.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+namespace {

Review comment:
       Why use an anonymous namespace here?




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: github-unsubscribe@arrow.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org