I have two dataframes:

a b c     d e f
2 4 6     6 7 1
4 7 9     9 5 87 9 65 8 2

Now I want to create a new dataframe like this:

a b c d e f 
2 4 6 6 7 1 
4 7 9 9 5 8 

That is, I only want the rows of the second dataframe until the number of rows matches with the first dataframe.

concat have join = 'inner'

pd.concat([x,y],join = 'inner', axis=1)
Out[184]: a  b  c  d  e  f
0  2  4  6  6  7  1
1  4  7  9  9  5  8