Jacek Pliszka created ARROW-18137:
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Summary: Allow passing no aggregations to TableGroupBy.aggregate
Key: ARROW-18137
URL: https://issues.apache.org/jira/browse/ARROW-18137
Project: Apache Arrow
Issue Type: New Feature
Components: C++, Python
Affects Versions: 9.0.0
Reporter: Jacek Pliszka
If we could allow TableGroupBy.aggregate to accept no aggregation functions
then it would behave like pandas drop_duplicates.
{code:python}
t.group_by(['keys', 'values']).aggregate()
{code}
I did some naive benchmarks and looks like it should be 30% faster than
converting to pandas and deduplicating. This was my naive test:
{code:python}
t.append_column('i', pa.array([1]*len(t),pa.int64())).group_by(['keys',
'values']).aggregate([("i", "max")]).drop(['i_max'])
{code}
And on small 5M table it took 245ms while 359ms for
t.to_pandas().drop_duplicates()
Actual aggregation without adding dummy column should be even faster still
will allow drop_duplicates functionality until better implementation arrives
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