pandas.core.groupby.DataFrameGroupBy.cummax#

DataFrameGroupBy.cummax(axis=_NoDefault.no_default, numeric_only=False, **kwargs)[source]#

Cumulative max for each group.

Returns:

Series or DataFrame

See also

Series.groupby: Apply a function groupby to a Series.
DataFrame.groupby: Apply a function groupby to each row or column of a DataFrame.

Examples

For SeriesGroupBy:

>>> lst = ['a', 'a', 'a', 'b', 'b', 'b']
>>> ser = pd.Series([1, 6, 2, 3, 1, 4], index=lst)
>>> ser
a    1
a    6
a    2
b    3
b    1
b    4
dtype: int64
>>> ser.groupby(level=0).cummax()
a    1
a    6
a    6
b    3
b    3
b    4
dtype: int64

For DataFrameGroupBy:

>>> data = [[1, 8, 2], [1, 1, 0], [2, 6, 9]]
>>> df = pd.DataFrame(data, columns=["a", "b", "c"],
...                   index=["cow", "horse", "bull"])
>>> df
        a   b   c
cow     1   8   2
horse   1   1   0
bull    2   6   9
>>> df.groupby("a").groups
{1: ['cow', 'horse'], 2: ['bull']}
>>> df.groupby("a").cummax()
        b   c
cow     8   2
horse   8   2
bull    6   9