Merging Multiple Dataframes by Multiple Columns

Question

I am trying to merge about 5 Data Frames, each with 2 variables. Each data frame has two variables. The variables are Unique_ID and Year. Each data frame has a different amount of observations.

DF 1

Unique ID        Year
1                2010
2                2010
3                2011

DF 2

Unique ID        Year
3                2010
2                2011
4                2012

What is the best way to merge them? I don't mind duplicates. I am actually trying to see how many I have.

What would be your expected output, just from merging the two dataframes you have posted above? You can add an arbitrary third column that can better showcase this. — David Erickson, Oct 14 '20 at 03:28

score 0 · Answer 1 · answered Oct 14 '20 at 03:16

0

You can use functools.partial:

import functools
dfs = [df1,df2,df3,df4,df5]
df = functools.partial(pd.merge, on=['Unique_ID', 'Year']) #may have to pass how='outer' or how='left', depending on what you are trying to accomplish

answered Oct 14 '20 at 03:16

David Erickson

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score 0 · Answer 2 · answered Oct 14 '20 at 03:48

0

you can use pandas.concat:

merged = pandas.concat([df1,df2,df3,df4,df5])

This will add up all your dataframes

answered Oct 14 '20 at 03:48

Josh C

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Merging Multiple Dataframes by Multiple Columns

2 Answers2