How to set the values under column value condition in pandas

Question

Here is my dataframe

    col1    col2
0   1.0     5.0
1   2.0     6.0
2   NaN     7.0
3   3.0     8.0

I want to add the column('col3') which has the value col1 or col2 as value condition. Col3 value is same to col1 but except if col1 value is 'NaN' then col3 value is set to col2.

My expected output is.

    col1    col2   col3
0   1.0     5.0    1.0
1   2.0     6.0    2.0
2   NaN     7.0    7.0
3   3.0     8.0    3.0

How can I do that?

``df["col3"] = df.col1.fillna(df.col2)`` ? – sammywemmy Jul 24 '20 at 06:35 — sammywemmy, Jul 24 '20 at 06:35

score 0 · Answer 1 · answered Jul 24 '20 at 06:37

0

pandas has a builtin function for that: combine_first

df["col3"] = df["col1"].combine_first(df["col2"])

answered Jul 24 '20 at 06:37

Maarten Fabré

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How to set the values under column value condition in pandas

1 Answers1