pandas.DataFrame.expanding

DataFrame.expanding(min_periods=1, center=False, axis=0)

Provides expanding transformations.

New in version 0.18.0.

Parameters:

min_periods : int, default 1

Minimum number of observations in window required to have a value (otherwise result is NA).

center : bool, default False

Set the labels at the center of the window.

axis : int or str, default 0

Returns:

a Window sub-classed for the particular operation

See also

rolling

Provides rolling window calculations.

ewm

Provides exponential weighted functions.

Notes

By default, the result is set to the right edge of the window. This can be changed to the center of the window by setting center=True.

Examples

>>> df = pd.DataFrame({'B': [0, 1, 2, np.nan, 4]})
     B
0  0.0
1  1.0
2  2.0
3  NaN
4  4.0

>>> df.expanding(2).sum()
     B
0  NaN
1  1.0
2  3.0
3  3.0
4  7.0