Pandas Replace Null With Column Name

Question

Given the following data frame: import pandas as pd

d = pd.DataFrame({'a':[1,2,3],'b':[np.nan,5,6]})
d
    a   b
0   1   NaN
1   2   5.0
2   3   6.0

For any column where a value is 'NaN', I'd like to replace that value with the column name. My real data has many columns.

Desired result:

    a   b
0   1   b
1   2   5.0
2   3   6.0

Thanks in advance!

MaxU - stand with Ukraine · Accepted Answer · 2017-08-22 18:45:44Z

5

IIUC:

In [60]: d.fillna(d.columns.to_series())
Out[60]:
   a  b
0  1  b
1  2  5
2  3  6

answered Aug 22, 2017 at 18:45

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5 Comments

Thanks, will mark as correct once I can. As a follow-up, what if I wanted to instead fill any non-null value with the column name?

@DanceParty2, that's an nteresting question! Let me try to find a solution for it...

Sure. I'll post as a separate question and share the link.