On Apr 11, 2018 20:52, zljubi...@gmail.com wrote:
>
> I have a dataframe:
>
> import pandas as pd
> import numpy as np
>
> df = pd.DataFrame( { 'A' : ['a', 'b', '', None, np.nan],
> 'B' : [None, np.nan, 'a', 'b', '']})
>
> A B
> 0 a None
> 1 b NaN
> 2 a
> 3 None b
> 4 NaN
>
>
> I would like to create column C in the following way:
> column C = column B if column B is not in [None, '', np.nan]
> else column A
>
> How to do that?
>
> I tried:
>
> df['C'] = df[['A', 'B']].apply(lambda x: x[1] if x[1] in [None, '', np.nan]
> else x[0])
>
> but I got all np.nan's.
This is another approach:
https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.replace.html
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