pandas.infer_freq(index, warn: bool = True) → Union[str, NoneType][source]

Infer the most likely frequency given the input index. If the frequency is uncertain, a warning will be printed.

indexDatetimeIndex or TimedeltaIndex

If passed a Series will use the values of the series (NOT THE INDEX).

warnbool, default True
str or None

None if no discernible frequency TypeError if the index is not datetime-like ValueError if there are less than three values.