Joris Van den Bossche created ARROW-6923:
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Summary: [C++] Option for Filter kernel how to handle nulls in the
selection vector
Key: ARROW-6923
URL: https://issues.apache.org/jira/browse/ARROW-6923
Project: Apache Arrow
Issue Type: Improvement
Components: C++
Reporter: Joris Van den Bossche
How nulls are handled in the boolean mask (selection vector) in a filter kernel
varies between languages / data analytics systems (e.g. base R propagates
nulls, dplyr R skips (sees as False), SQL generally skips them as well I think,
Julia raises an error).
Currently, in Arrow C++ we "propagate" nulls (null in the selection vector
gives a null in the output):
{code}
In [7]: arr = pa.array([1, 2, 3])
In [8]: mask = pa.array([True, False, None])
In [9]: arr.filter(mask)
Out[9]:
<pyarrow.lib.Int64Array object at 0x7fefe44b3048>
[
1,
null
]
{code}
Given the different ways this could be done (propagate, skip, error), should we
provide an option to control this behaviour?
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