Merge tables with index column in pandas

Question

I need to join two tables:

I use the next code:

    table = pd.merge(df1, df2, on=['user-reference_id'], how = 'right')

But it doesn´t work. I have obtained duplicated values.

The result i need to obtain is:

user-reference_id	reference_date	first_purchase	month
159	2019-06-14	62.95	6
5009	2017-10-19	58.50	10
5026	2017-07-04	35.52	7
5032	2017-01-02	71.68	1

Answer 1

Edit: I misunderstood your case so I have changed my answer.

The type of merge to be performed is wrong. You need to change your keyword argument on the how parameter. Change it to:

table = pd.merge(df1, df2, on=['user-reference_id'], how='outer')

There are a couple of links that are related e.g. :

Difference(s) between merge() and concat() in pandas

Pandas/Python: How to concatenate two dataframes without duplicates?

https://pandas.pydata.org/pandas-docs/stable/user_guide/merging.html#