Merge multiple DataFrames Pandas

Question

This might be considered as a duplicate of a thorough explanation of various approaches, however I can\'t seem to find a solution to my problem there due to a higher number

Answer 1

A simple way is with a combination of functools.partial/reduce.

Firstly partial allows to "freeze" some portion of a function’s arguments and/or keywords resulting in a new object with a simplified signature. Then with reduce we can apply cumulatively the new partial object to the items of iterable (list of dataframes here):

from functools import partial, reduce

dfs = [df1, df2, df3]
merge = partial(pd.merge, on=['depth', 'profile'], how='outer')
reduce(merge, dfs)

   depth       VAR1    profile     VAR2    VAR3
0    0.6  38.198002  profile_1  0.20440     NaN
1    0.6  38.198002  profile_1  0.20440     NaN
2    1.3  38.200001  profile_1      NaN  15.182
3    1.1        NaN  profile_1  0.20442     NaN
4    1.2        NaN  profile_1  0.20446  15.188
5    1.4        NaN  profile_1      NaN  15.182