Antoine Pitrou created ARROW-2453:
-------------------------------------

             Summary: [Python] Improve Table column access
                 Key: ARROW-2453
                 URL: https://issues.apache.org/jira/browse/ARROW-2453
             Project: Apache Arrow
          Issue Type: Improvement
          Components: Python
    Affects Versions: 0.9.0
            Reporter: Antoine Pitrou


Suppose you have a table column named "nulls". Right now, to access it on a 
table, you need to do something like this:
{code:python}
>>> table.column(table.schema.get_field_index('nulls'))
<pyarrow.lib.Column object at 0x7fe4144d2570>
chunk 0: <pyarrow.lib.NullArray object at 0x7fe3db51b4a8>
[
  NA,
  NA,
  NA
]
{code}

Also, if you mistype the column name, instead of getting an error you get an 
arbitrary column:
{code}
>>> table.column(table.schema.get_field_index('z'))
<pyarrow.lib.Column object at 0x7fe3dbd6cc30>
chunk 0: <pyarrow.lib.Int64Array object at 0x7fe3db54b408>
[
  0,
  1,
  2
]
{code}

{{Table.column()}} should accept a string object and return the column with the 
corresponding name. KeyError should be raised if there is no column with a such 
name.




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