Pandas Merge On Multiple Columns

Question

I need to merge the below two dataframes to yield the below result.

Table_1

foo1	foo2	date	value1	value2
a	b	4/20	6	NaN
a	b	4/19	NaN	2
a	b	4/18	NaN	1

Table_2

foo1	foo2	date	value3
a	b	4/20	2
a	b	4/10	1

I'm able to yield the below result using this merge.

table_1 = table_1.merge(table_2,how='outer',left_on=['foo1','foo2','date'],right_on=['foo1','foo2','date'])

Resulting table

foo1	foo2	date	value1	value2	value3
a	b	4/20	6	NaN	NaN
a	b	4/19	NaN	2	NaN
a	b	4/18	NaN	1	NaN
a	b	4/20	NaN	NaN	2
a	b	4/10	NaN	NaN	1

I need any of the rows that match with those three columns to merge together.

Ideal result

foo1	foo2	date	value1	value2	value3
a	b	4/20	6	NaN	2
a	b	4/19	NaN	2	NaN
a	b	4/18	NaN	1	NaN
a	b	4/10	NaN	NaN	1

How should I merge these two dataframes?

Answer 1

you could do this:

pd.merge(Table_1, Table_2, how="outer", on=['foo1','foo2','date'])