pandas.core.window.Expanding.sum

Expanding.sum(*args, **kwargs)

Calculate expanding sum of given DataFrame or Series.

Parameters:

*args, **kwargs

For compatibility with other expanding methods. Has no effect on the computed value.

Returns:

Series or DataFrame

Same type as the input, with the same index, containing the expanding sum.

See also

Series.sum

Reducing sum for Series.

DataFrame.sum

Reducing sum for DataFrame.

Examples

>>> s = pd.Series([1, 2, 3, 4, 5])
>>> s
0    1
1    2
2    3
3    4
4    5
dtype: int64

>>> s.rolling(3).sum()
0     NaN
1     NaN
2     6.0
3     9.0
4    12.0
dtype: float64

>>> s.expanding(3).sum()
0     NaN
1     NaN
2     6.0
3    10.0
4    15.0
dtype: float64

>>> s.rolling(3, center=True).sum()
0     NaN
1     6.0
2     9.0
3    12.0
4     NaN
dtype: float64

For DataFrame, each expanding sum is computed column-wise.

>>> df = pd.DataFrame({"A": s, "B": s ** 2})
>>> df
   A   B
0  1   1
1  2   4
2  3   9
3  4  16
4  5  25

>>> df.rolling(3).sum()
      A     B
0   NaN   NaN
1   NaN   NaN
2   6.0  14.0
3   9.0  29.0
4  12.0  50.0