reducer2.py

#!/usr/bin/env python

import sys

def read_mapper_output(file, separator='\t'):
    for line in file:
        yield line.rstrip().split(separator, 1)

def main(separator='\t'):
    # Input comes from STDIN
    data = read_mapper_output(sys.stdin, separator=separator)
    # Extract the 10 first items
    for i in range(10):
        uri = data.next()
        print "%s%s%s" % (uri[1], separator, uri[0])
    for uri in data:
        continue

if __name__ == "__main__":
    main()