Method groupby

dask/dataframe/dask_expr/_collection.py:3025–3043

(
        self, by, group_keys=True, sort=None, observed=None, dropna=None, **kwargs
    )

    @derived_from(pd.DataFrame)
    def groupby(
        self, by, group_keys=True, sort=None, observed=None, dropna=None, **kwargs
    ):
        from dask.dataframe.dask_expr._groupby import GroupBy

        if isinstance(by, FrameBase) and not isinstance(by, Series):
            raise ValueError(
                f"`by` must be a column name or list of columns, got {by}."
            )

        return GroupBy(
            self,
            by,
            group_keys=group_keys,
            sort=sort,
            observed=observed,
            dropna=dropna,
            **kwargs,
        )

    def __setitem__(self, key, value):
        if isinstance(key, (tuple, list)) and isinstance(value, DataFrame):