In [4]: pd.__version__ Out[4]: u'0.18.1' 

The docstring for Series.replace refers to looking up column names, which AFAIK doesn't make sense for the Series version of replace. It seems like the Series function is just blindly inheriting the DataFrame docstring?

http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.replace.html?highlight=replace#pandas.Series.replace

http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.replace.html?highlight=replace#pandas.DataFrame.replace

For example, the following trivial example of Series.replace() does not agree with the docstring:

import pandas as pd x = pd.DataFrame([dict(A=1, B=2, C=3), dict(A=2, B=3, C=4), dict(A=3, B=4, C=5)]) print(x.A.replace({1:0})) print(x.A) 0 0 1 2 2 3 Name: A, dtype: int64 0 1 1 2 2 3 Name: A, dtype: int64