pizza.py

#!/usr/bin/env python3

import sys
import collections
import functools
import operator


def read(filename):
    with open(filename, encoding='utf-8') as f:
        for line in f:
            yield set(map(str.strip, line.split(',')))


def get_most_common(common, items):
    for item, n in common:
        if item in items:
            return item


def sort(counter):
    counter = sorted(counter.items())
    counter.sort(key=operator.itemgetter(1), reverse=True)
    return counter


def main():
    # Read data
    itemsets = list(read(sys.argv[1]))

    # Count most common choices
    common = collections.Counter()
    for items in itemsets:
        common.update(items)
    common = sort(common)
    for items, n in common:
        print("%3d   %s" % (n, items))

    print()
    print('-' * 42)
    print()

    # Print final results
    func = functools.partial(get_most_common, common)
    result = collections.Counter(map(func, itemsets))
    for items, n in sort(result):
        print("%3d   %s" % (n, items))


if __name__ == '__main__':
    main()