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# pandas.api.typing.Expanding.skew

Expanding.skew(numeric_only=False)

  Calculate the expanding unbiased skewness.

  Computes the third standardized moment over all data points seen so far, measuring the asymmetry of the distribution.

  Parameters:
    numeric_only bool, default False

      Include only float, int, boolean columns.

  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.

  `Series.expanding`

    Calling expanding with Series data.

  `DataFrame.expanding`

    Calling expanding with DataFrames.

  `Series.skew`

    Aggregating skew for Series.

  `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