[GitHub] [arrow] bmschmidt opened a new issue, #14988: Raise IndexError when pa.Schema.get_field_index fails

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

bmschmidt opened a new issue, #14988:
URL: https://github.com/apache/arrow/issues/14988

   ### Describe the enhancement requested
   
   Thanks to everyone who works on this project.
   
   I want to report what seems to me a less-than-ideal behavior in the python API. `Schema.get_field_index()` returns -1 to indicate that a given column is not in the list (C-style), but `Schema.get_field(-1)` returns the last element in the list (python-style). In concert these can raise opaque bugs that are a little hard to track down.
   
   Example:
   ```python
   schema = pa.schema([
       pa.field('n_legs', pa.int64()),
       pa.field('animals', pa.string()),
   ])
   
   # Returns -1 to indicate that the column doesn't exist
   nonexistent_field = schema.get_field_index("n_eyes")
   # Happily consumes -1 to return the field for 'animals.'
   schema.field(nonexistent_field)
   ```
   
   I would expect a python library would raise a `ValueError` when you request the index for a key that doesn't exist. That's my proposal here, I guess. (That is, schema.get_field_index should behave the same as python's native `List.index()` method.); I'm also not convinced that negative-style indexing on schema.field is very desirable, but that's probably it's the sort of feature that can't be removed. Failing either of these, it might be worth putting a note in the docs that `Schema.field` and `Schema.get_field_index` don't play as well together as one might expect.
   
   ### Component(s)
   
   Python


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Re: [I] [Python] Raise IndexError when pa.Schema.get_field_index fails [arrow]

["thisisnic (via GitHub)" <gi...@apache.org>]

thisisnic commented on issue #14988:
URL: https://github.com/apache/arrow/issues/14988#issuecomment-3921584184

   This issue has been marked as stale because it has had no activity in the past 2 years. Please remove the stale label or comment below, or this issue will be closed in 14 days.


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Re: [I] [Python] Raise IndexError when pa.Schema.get_field_index fails [arrow]

["thisisnic (via GitHub)" <gi...@apache.org>]

thisisnic closed issue #14988: [Python] Raise IndexError when pa.Schema.get_field_index fails
URL: https://github.com/apache/arrow/issues/14988


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