pandas.Index.map

Index.map(mapper, na_action=None) [source]

Map values using input correspondence (a dict, Series, or function).

Parameters:	mapper : function, dict, or Series Mapping correspondence. na_action : {None, ‘ignore’} If ‘ignore’, propagate NA values, without passing them to the mapping correspondence.
Returns:	applied : Union[Index, MultiIndex], inferred The output of the mapping function applied to the index. If the function returns a tuple with more than one element a MultiIndex will be returned.