How to get the intersection of two dataframes?

Question

I have two dataframes of similar format:

df1 = DataFrame({'a':[0,1,2,3,4], 'b':['q','r','s','t','u']})
df1

    a   b
0   0   q
1   1   r
2   2   s
3   3   t
4   4   u

df2 = DataFrame({'a':[4,3,2,1,999], 'b':['u','r','s','t','u']})
df2

    a   b
0   4   u
1   3   r
2   2   s
3   1   t
4   999 u

I would like to get a new dataframe that has rows that appear in both of these (ignoring the index). So the above example gives a dataframe

    a   b
0   4   u
1   2   s

How do I get this intersection?

Answer 1

You can just perform a merge, this will use all columns and the default type of merge is inner so values must be present in both dfs:

In [71]:

df1.merge(df2)
Out[71]:
   a  b
0  2  s
1  4  u