pandas.core.window.expanding.Expanding.skew#

Expanding.skew(numeric_only=False)[source]#

Calculate the expanding unbiased skewness.

Parameters:

numeric_onlybool, default False: Include only float, int, boolean columns.

Added in version 1.5.0.

Returns:

Series or DataFrame: Return type is the same as the original object with np.float64 dtype.

See also

scipy.stats.skew: Third moment of a probability density.
pandas.Series.expanding: Calling expanding with Series data.
pandas.DataFrame.expanding: Calling expanding with DataFrames.
pandas.Series.skew: Aggregating skew for Series.
pandas.DataFrame.skew: Aggregating skew for DataFrame.

Notes

A minimum of three periods is required for the rolling calculation.

Examples

>>> ser = pd.Series([-1, 0, 2, -1, 2], index=['a', 'b', 'c', 'd', 'e'])
>>> ser.expanding().skew()
a         NaN
b         NaN
c    0.935220
d    1.414214
e    0.315356
dtype: float64