gistfile1.py

#!/usr/bin/env python
# encoding: utf-8

import sys, os, re, random

def mapper(args):
    for line in sys.stdin:
        sys.stdout.write(line.strip() + "\n")

def reducer(args):
    for line in sys.stdin:
        line = line.strip()
        sys.stdout.write("\t".join(line.split(",")) + "\n")

if __name__  == "__main__":
    if len(sys.argv) == 1:
        os.system('cat ratings.csv | ./user_stats.py mapper  | LC_ALL=C sort | ./user_stats.py reducer')
    elif sys.argv[1] == "mapper":
        mapper(sys.argv[2:])
    elif  sys.argv[1] == "reducer":
        reducer(sys.argv[2:])