Combine two Pandas dataframes with the same index

Question

I have two dataframes with the same index but different columns. How do I combine them into one with the same index but containing all the columns?

I have:

and I need the following output:

  A  B
1 10 20
2 11 21

score 113 · Accepted Answer · answered Feb 27 '15 at 20:30

113

pandas.concat([df1, df2], axis=1)

answered Feb 27 '15 at 20:30

BrenBarn

3

why use pd.concat over pd.merge? – Liam Foley Feb 27 '15 at 21:32
13

@LiamFoley: `merge` is for join-style operations. If you just want to concatenate DataFrames, that's what `concat` is for. – BrenBarn Feb 27 '15 at 21:34
5

Thanks! I would write `pandas.concat([df1, df2], axis='columns')` For a more readable version – Alon Samuel Sep 13 '22 at 15:00

unique_beast · Answer 2 · 2017-01-18T21:51:36.070

20

You've got a few options depending on how complex the dataframe is:

Option 1:

df1.join(df2, how='outer')

Option 2:

pd.merge(df1, df2, left_index=True, right_index=True, how='outer')

edited Jan 18 '17 at 21:51

answered Feb 28 '15 at 05:00

unique_beast

2 Answers2