Pandas dataframe Cartesian join

Question

I have two pandas dataframes, and I would like to combine each second dataframe row with each first dataframe row like this:

First:

val1 val2
1    2
0    0
2    1

Second:

l1 l2
a    a
b    c

Result (expected result size = len(first) * len(second)):

val1 val2 l1 l2
1    2    a    a
1    2    b    c
0    0    a    a
0    0    b    c
2    1    a    a
2    1    b    b

They have no same index.

Regards, Secau

Answer 1

Create a surrogate key to do a cartesian join between them...

import pandas as pd

df1 = pd.DataFrame({'A': [1, 0, 2],
                    'B': [2, 0, 1],
                    'tmp': 1})

df2 = pd.DataFrame({'l1': ['a', 'b'],
                    'l2': ['a', 'c'],
                    'tmp': 1})

print pd.merge(df1, df2, on='tmp', how='outer')

Result:

   A  B  tmp l1 l2 
0  1  2    1  a  a 
1  1  2    1  b  c 
2  0  0    1  a  a 
3  0  0    1  b  c 
4  2  1    1  a  a 
5  2  1    1  b  c