pandas.errors.NullFrequencyError#
- exception pandas.errors.NullFrequencyError[source]#
- Exception raised when a - freqcannot be null.- Particularly - DatetimeIndex.shift,- TimedeltaIndex.shift,- PeriodIndex.shift.- See also - Index.shift
- Shift values of Index. 
- Series.shift
- Shift values of Series. 
 - Examples - >>> df = pd.DatetimeIndex(["2011-01-01 10:00", "2011-01-01"], freq=None) >>> df.shift(2) Traceback (most recent call last): NullFrequencyError: Cannot shift with no freq