pandas.core.groupby.SeriesGroupBy.filter

SeriesGroupBy.filter(func, dropna=True, *args, **kwargs)

Filter elements from groups that don’t satisfy a criterion.

Elements from groups are filtered if they do not satisfy the boolean criterion specified by func.

Parameters:

funcfunction

Criterion to apply to each group. Should return True or False.

dropnabool

Drop groups that do not pass the filter. True by default; if False, groups that evaluate False are filled with NaNs.

Returns:

Series

Notes

Functions that mutate the passed object can produce unexpected behavior or errors and are not supported. See Mutating with User Defined Function (UDF) methods for more details.

Examples

>>> df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
...                           'foo', 'bar'],
...                    'B' : [1, 2, 3, 4, 5, 6],
...                    'C' : [2.0, 5., 8., 1., 2., 9.]})
>>> grouped = df.groupby('A')
>>> df.groupby('A').B.filter(lambda x: x.mean() > 3.)
1    2
3    4
5    6
Name: B, dtype: int64