Tag: pandas-join

Pandas Equivalent of SQL CROSS JOIN (Cartesian Product)

Let’s say I had two tables:

Table1:

   col1  col2
      0     1
      2     3

Table2:

   col3  col4
      5     6
      7     8

In SQL, if I made the following statement:

Select *
From Table1, Table2;

I would expect to get back a table with all combinations from both tables:

col1 col2 col3 col4
   0    1    5    6
   0    1    7    8
   2    3    5    6
   2    3    7    8

Is there a way to do the same thing with two dataframes in pandas?

Solution:

A standard idiom is using the merge on a dummy column.

df1.assign(foo=1).merge(df2.assign(foo=1)).drop('foo', 1)

   col1  col2  col3  col4
0     0     1     5     6
1     0     1     7     8
2     2     3     5     6
3     2     3     7     8