DatetimeIndex.
mean
Return the mean value of the Array.
New in version 0.25.0.
Whether to ignore any NaT elements.
Timestamp or Timedelta.
See also
numpy.ndarray.mean
Returns the average of array elements along a given axis.
Series.mean
Return the mean value in a Series.
Notes
mean is only defined for Datetime and Timedelta dtypes, not for Period.