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Table·
method
Table.group_by
groups by one or more columns; chain .agg to reduce
Python
group_by(*keys: str) -> GroupBy
Returns GroupBy — an intermediate; call .agg(col=func, ...) to reduce
Parameters#
| name | type | default | description |
|---|---|---|---|
*keys |
str |
— | one or more columns to group by (a single list or tuple also works) |
Example#
Python
t.group_by("team").agg(score="mean", n="count")
# → one row per team with mean score + row count
Notes#
group_by returns an intermediate — call .agg(**aggs) on it, where each value is a
pyarrow function name ("mean", "sum", "count", "min", "max", …). The result keeps
the grouping keys plus one column per aggregation, named after the original column
(score stays score, not score_mean). A single list or tuple of keys is accepted.
See also#
API: join · null_report · sort
Guides: Tables & data flow
By LSD Team · Last updated Jul 17, 2026
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