Series.
expanding
Provide expanding transformations.
Minimum number of observations in window required to have a value (otherwise result is NA).
Set the labels at the center of the window.
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.
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