Is there any python built-in method that allows us to know all the possible pairs/combinations in a list?

Question

Is there any method from python standart libraries that gives us the possibility to know all the possible combinations between two elements of a list (pairs). I have already made this function myself, and it looks like this:

def allPossiblePairs(list):
    l = len(list)
    pfinal = l - 1 # retirar
    pos2 = 0
    sums = []
    for pos in range(l):
        element = list[pos]
        pos2 = pos
        while pos2 != pfinal:
            pos2 += 1
            tosum = list[pos2]
            pair = tuple((element, tosum))
            sums.append(pair)
    return(sums)

list1 = [1, 2, 3, 4, 5]
print(allPossiblePairs(list1))

This function will return the following list of tuples: [(1, 2), (1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5), (3, 4), (3, 5), (4, 5)]

Also, this is not efficient, it is quite slow because you have a while loop in a for loop, iterating through each element in the list (for) and doing it again removing the previous element (while). Is there any way to do this without having to create a new function?

Answer 1

This is itertools.combinations:

>>> list(combinations([1,2,3,4,5], 2))
[(1, 2), (1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5), (3, 4), (3, 5), (4, 5)]

Your function is just combinations with the second argument fixed to 2.