update columns of dataframe with columns of another dataframe and preserve column order

Question

df1 = pd.DataFrame(columns=['a','B','c','D'])    
df2 = pd.DataFrame({'a':[1,2],'B':[3,4]})

I'd like to update the empty columns in df1 with df2 but keeping the original column order. I tried

df1.combine_first(df2)

but this changes the order of the columns

   B   D  a   c
0  3 NaN  1 NaN
1  4 NaN  2 NaN

Does this answer your question? Sorting Pandas Dataframe by order of another index — Trenton McKinney
– Trenton McKinney, Commented Aug 13, 2020 at 1:39

BENY · Accepted Answer · 2020-08-13 01:18:09Z

1

Try with reindex

df2.reindex(df1.columns, axis=1)
Out[44]: 
   a  B   c   D
0  1  3 NaN NaN
1  2  4 NaN NaN

answered Aug 13, 2020 at 1:18

BENY

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