# pandas.Series.expanding

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

  Provide 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

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