pandas.Series.apply

Series.apply(func, convert_dtype=True, args=(), **kwds)

Invoke function on values of Series. Can be ufunc (a NumPy function that applies to the entire Series) or a Python function that only works on single values

func : function convert_dtype : boolean, default True

Try to find better dtype for elementwise function results. If False, leave as dtype=object

Series.map: For element-wise operations

y : Series or DataFrame if func returns a Series