Not able to outer join two dataframe

Question

I am using this code to merge two dataframe : pd.concat(df1, df2, on='a', how='outer')

I am getting the following error:-

TypeError: concat() got an unexpected keyword argument 'on'

user_2901002 · Answer

I believe you want merge:

df = pd.merge(df1, df2, on='a', how='outer')

But also concat is possible - it return default outer join by index of both DataFrames, so added [] and DataFrame.set_index:

df = pd.concat([df1.set_index('a'), df2.set_index('a')], axis=1)

user_6101680 · Answer

You should try the merge method.

pd.merge(df1, df2, how='outer', on='a')

user_8702178 · Answer

Here's the documentation for concat. As you can see, there is no 'on' (or how) arg, so you just need to adjust your parameters accordingly.