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feat: Support len() on Groupby objects #2183

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Merged
TrevorBergeron merged 2 commits into from
Oct 22, 2025
Merged

feat: Support len() on Groupby objects #2183

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ba3fbc2
feat: Support len() on Groupby objects
TrevorBergeron Oct 20, 2025
520b9b4
test spacing
TrevorBergeron Oct 22, 2025
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3 changes: 3 additions & 0 deletions bigframes/core/groupby/dataframe_group_by.py
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Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,9 @@ def __iter__(self) -> Iterable[Tuple[blocks.Label, df.DataFrame]]:
filtered_df = df.DataFrame(filtered_block)
yield group_keys, filtered_df

def __len__(self) -> int:
return len(self.agg([]))

def size(self) -> typing.Union[df.DataFrame, series.Series]:
agg_block, _ = self._block.aggregate_size(
by_column_ids=self._by_col_ids,
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9 changes: 6 additions & 3 deletions bigframes/core/groupby/series_group_by.py
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Expand Up @@ -108,6 +108,9 @@ def __iter__(self) -> Iterable[Tuple[blocks.Label, series.Series]]:
filtered_series.name = self._value_name
yield group_keys, filtered_series

def __len__(self) -> int:
return len(self.agg([]))

def all(self) -> series.Series:
return self._aggregate(agg_ops.all_op)

Expand Down Expand Up @@ -275,9 +278,9 @@ def agg(self, func=None) -> typing.Union[df.DataFrame, series.Series]:
if column_names:
agg_block = agg_block.with_column_labels(column_names)

if len(aggregations) > 1:
return df.DataFrame(agg_block)
return series.Series(agg_block)
if len(aggregations) == 1:
return series.Series(agg_block)
return df.DataFrame(agg_block)

aggregate = agg

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16 changes: 16 additions & 0 deletions tests/system/small/test_groupby.py
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Expand Up @@ -61,6 +61,15 @@ def test_dataframe_groupby_head(scalars_df_index, scalars_pandas_df_index):
pd.testing.assert_frame_equal(pd_result, bf_result, check_dtype=False)


def test_dataframe_groupby_len(scalars_df_index, scalars_pandas_df_index):
col_names = ["int64_too", "float64_col", "int64_col", "bool_col", "string_col"]

bf_result = len(scalars_df_index[col_names].groupby("bool_col"))
pd_result = len(scalars_pandas_df_index[col_names].groupby("bool_col"))

assert bf_result == pd_result
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@sycai sycai Oct 21, 2025

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style nits: empty spaces between "arrange" "act" "assert" blocks: https://g3doc.corp.google.com/eng/doc/devguide/testing/unit/best-practices.md?cl=head&polyglot=python#structure

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@TrevorBergeron TrevorBergeron Oct 22, 2025

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added



def test_dataframe_groupby_median(scalars_df_index, scalars_pandas_df_index):
col_names = ["int64_too", "float64_col", "int64_col", "bool_col", "string_col"]
bf_result = (
Expand Down Expand Up @@ -668,6 +677,13 @@ def test_dataframe_groupby_last(
# ==============


def test_series_groupby_len(scalars_df_index, scalars_pandas_df_index):
bf_result = len(scalars_df_index.groupby("bool_col")["int64_col"])
pd_result = len(scalars_pandas_df_index.groupby("bool_col")["int64_col"])

assert bf_result == pd_result


@pytest.mark.parametrize(
("agg"),
[
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