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pythonlistpython-itertoolscartesian-product

How to calculate a Cartesian product of a list with itself


For example,

list = [0, 1, 2]

I want a list of all possible 2-combinations:

combinations = [(0,0), (0,1), (0,2), (1,0), (1,1), (1,2), (2,0), (2,1), (2,2)]

It seems to me that all the tools in itertools in Python only make one of (1,0) and (0,1), not both, I need both. Any suggestions, other than entering them by hand?


Solution

  • You are looking for a Cartesian product of that list with itself, not a permutation nor a combination. Therefore you should use itertools.product with repeat=2:

    from itertools import product
    
    li = [0, 1, 2]
    print(list(product(li, repeat=2)))
    >> [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]