Question

The itertools function has no error but it also doesn’t print anything once its complete.
My code is:

def comb(iterable, r):
    pool = tuple(iterable)
    n = len(pool)
    for indices in permutations(range(n), r):
        if sorted(indices) == list(indices):
            print (indices)
            yield tuple(pool[i] for i in indices)

I included the print statement but it doesn’t print the total combinations it calculated.

Answer 1

You need to read up on how generators work. When you call comb() it returns a generator object. You need to then do something with the generator object to get the objects returned from it.

from itertools import permutations

lst = range(4)
result = list(comb(lst, 2))  # output of print statement is now shown

print(result) # prints: [(0, 1), (0, 2), (0, 3), (1, 2), (1, 3), (2, 3)]

comb() returns a generator object. Then, list() iterates it and collects the values in a list. At the time of iteration, your print statement fires.