mapper2.py

#!/usr/bin/env python

import sys

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

def main(separator='\t'):
    # Input comes from STDIN
    data = read_input(sys.stdin)
    for uri in data:
        # Invert <number of properties> and <subject>
        print '%s%s%s' % (uri[1], separator, uri[0])

if __name__ == "__main__":
    main()