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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2023/01/04 01:50:11 UTC

[GitHub] [arrow-rs] wjones127 opened a new issue, #3448: Add column_by_name() for RecordBatch

wjones127 opened a new issue, #3448:
URL: https://github.com/apache/arrow-rs/issues/3448

   **Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
   
   This is quite verbose:
   
   ```rust
   let col: Option<ArrayRef> = record_batch.column(record_batch.schema().column_with_name("my_column"))
   ```
   
   **Describe the solution you'd like**
   
   The simplest option is to add `column_by_name()` for `RecordBatch`. It is already implemented for `StructArray`.
   
   ```rust
   let col: Option<ArrayRef> = record_batch.column_by_name("my_column")
   ```
   
   But it might also be desirable to implement [std::ops::Index](https://doc.rust-lang.org/std/ops/trait.Index.html) for `RecordBatch`:
   
   ```rust
   let col: Option<ArrayRef> = record_batch["my_column"]
   ```
   
   **Describe alternatives you've considered**
   <!--
   A clear and concise description of any alternative solutions or features you've considered.
   -->
   
   **Additional context**
   
   I was working with highly nested schemas with multiple levels of StructArrays in some unit tests, and it was a little annoying to access those deep fields. In an ideal world, I might be able to do something along the lines of:
   
   ```rust
   let col: Option<ArrayRef> = record_batch["top_level_column"]?
       .as_struct_array()?["mid_level_column"]
       .as_struct_array()?["inner_column"];
   ```
   
   This implies `StructArray` would implement `Index` in the same way that `RecordBatch` does. If we wanted to get fancy, it might not be crazy to implement this for `ListArray` or even `MapArray`.


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[GitHub] [arrow-rs] ttencate commented on issue #3448: Add column_by_name() for RecordBatch

Posted by "ttencate (via GitHub)" <gi...@apache.org>.
ttencate commented on issue #3448:
URL: https://github.com/apache/arrow-rs/issues/3448#issuecomment-1720903747

   This is done and can be closed, right?


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[GitHub] [arrow-rs] askoa commented on issue #3448: Add column_by_name() for RecordBatch

Posted by GitBox <gi...@apache.org>.
askoa commented on issue #3448:
URL: https://github.com/apache/arrow-rs/issues/3448#issuecomment-1371608561

   I don't think we can return Option (or Result) from `std::ops::Index`. The trait function `index` returns a reference and hence cannot be a value created in the function. The function has to return reference to an item in `self`. 
   
   ```
   pub trait Index<Idx>
   where
       Idx: ?Sized,
   {
       type Output: ?Sized;
   
       fn index(&self, index: Idx) -> &Self::Output;
   }
   ```
   
   So the behavior of `record_batch["name"]` will be similar to `record_batch.column(index)`.  
   
   Below are the return types I am planning.  Let me know if you have alternate suggestion.
     -  `column_by_name` will return `Option<ArrayRef>` 
     - `column[name]` will return `&ArrayRef`. The function will panic if the given name is not in the schema.
   
   


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[GitHub] [arrow-rs] tustvold commented on issue #3448: Add column_by_name() for RecordBatch

Posted by GitBox <gi...@apache.org>.
tustvold commented on issue #3448:
URL: https://github.com/apache/arrow-rs/issues/3448#issuecomment-1370599167

   Makes sense to me


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[GitHub] [arrow-rs] askoa commented on issue #3448: Add column_by_name() for RecordBatch

Posted by GitBox <gi...@apache.org>.
askoa commented on issue #3448:
URL: https://github.com/apache/arrow-rs/issues/3448#issuecomment-1371550436

   I'll pick this up.


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[GitHub] [arrow-rs] tustvold closed issue #3448: Add column_by_name() for RecordBatch

Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold closed issue #3448: Add column_by_name() for RecordBatch
URL: https://github.com/apache/arrow-rs/issues/3448


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