pandas.core.groupby.SeriesGroupBy.cumsum#

SeriesGroupBy.cumsum(axis=_NoDefault.no_default, *args, **kwargs)[source]#

Cumulative sum 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', 'b']
>>> ser = pd.Series([6, 2, 0], index=lst)
>>> ser
a    6
a    2
b    0
dtype: int64
>>> ser.groupby(level=0).cumsum()
a    6
a    8
b    0
dtype: int64

For DataFrameGroupBy:

>>> data = [[1, 8, 2], [1, 2, 5], [2, 6, 9]]
>>> df = pd.DataFrame(data, columns=["a", "b", "c"],
...                   index=["fox", "gorilla", "lion"])
>>> df
          a   b   c
fox       1   8   2
gorilla   1   2   5
lion      2   6   9
>>> df.groupby("a").groups
{1: ['fox', 'gorilla'], 2: ['lion']}
>>> df.groupby("a").cumsum()
          b   c
fox       8   2
gorilla  10   7
lion      6   9