Cross factor generator

cross_factor.py

"""
cross_factor.py - describe

Terry N. Brown, [email protected], Mon Apr 03 13:28:41 2017
"""

from collections import namedtuple

def cross_factor(lists):
    """Return (as namedtuples) all combinations of elements from dict of lists"""
    keys = lists.keys()
    Record = namedtuple("Record", keys + ['r_pos', 'r_len'])
    pos = [0] * len(keys)
    lengths = [len(lists[k]) for k in keys]
    while True:
        values = {k:lists[k][pos[n]] for n, k in enumerate(keys)}
        values.update({'r_pos': pos, 'r_len': lengths})
        yield Record(**values)
        i = len(keys)-1
        pos[i] += 1
        if pos[i] == lengths[i]:
            while pos[i] == lengths[i] and i > 0:
                pos[i] = 0
                i -= 1
                pos[i] += 1
                if pos[i] < lengths[i]:
                    break
            else:
                return

def main():
    for i in cross_factor({'ltr': 'AB', 'num': [1,2,[3,4]], 'type': (str, int)}):
        print i

if __name__ == '__main__':
    main()