I am trying to build a 2d list of test cases that contains all the possible cases (‘+’, ‘-‘, ‘*’, ‘/’) like this:

[['+', '+', '+', '+'],
 ['+', '+', '+', '-'],
 ['+', '+', '-', '-'],
......
['/', '/', '/', '/']]

I am thinking to create it in a Python list comprehension. I tried:

[[x] * 4 for x in ('+','-','*', '/')]

but the result is not something I want. Anyone knows how to do it? Thanks.

>Solution :

itertools.combinations_with_replacement?

In [1]: from itertools import combinations_with_replacement
In [2]: list(combinations_with_replacement(["+", "-", "/", "*"], 4))
Out[2]:
[('+', '+', '+', '+'),
 ('+', '+', '+', '-'),
 ('+', '+', '+', '/'),
 ('+', '+', '+', '*'),
 ('+', '+', '-', '-'),
 ('+', '+', '-', '/'),
 ('+', '+', '-', '*'),
 ('+', '+', '/', '/'),
 ('+', '+', '/', '*'),
 ('+', '+', '*', '*'),
 ('+', '-', '-', '-'),
 ('+', '-', '-', '/'),
 ('+', '-', '-', '*'),
 ('+', '-', '/', '/'),
 ('+', '-', '/', '*'),
 ('+', '-', '*', '*'),
 ('+', '/', '/', '/'),
 ('+', '/', '/', '*'),
 ('+', '/', '*', '*'),
 ('+', '*', '*', '*'),
 ('-', '-', '-', '-'),
 ('-', '-', '-', '/'),
 ('-', '-', '-', '*'),
 ('-', '-', '/', '/'),
 ('-', '-', '/', '*'),
 ('-', '-', '*', '*'),
 ('-', '/', '/', '/'),
 ('-', '/', '/', '*'),
 ('-', '/', '*', '*'),
 ('-', '*', '*', '*'),
 ('/', '/', '/', '/'),
 ('/', '/', '/', '*'),
 ('/', '/', '*', '*'),
 ('/', '*', '*', '*'),
 ('*', '*', '*', '*')]