mapper1.py

#!/usr/bin/env python

import re
import sys

# Match the first <item> of the line
subjectRegEx = re.compile("^<([^>]+)>")
# Match the second <item> of the line
propertyRegEx = re.compile("^<[^>]+>\s<([^>]+)>")

def read_input(file):
    for line in file:
        # Remove leading and trailing whitespace
        line = line.strip()
        # Split the line according to a regex
        # capture the content of the first <item>
        subject = subjectRegEx.match(line)
        if(subject != None):
            # capture the content of the second <item>
            propertyValue = propertyRegEx.match(line)
            prpt = propertyValue.group(1) if (propertyValue != None) else None
            yield (subject.group(1), prpt)
        else:
            yield (None, None)

def main(separator='\t'):
    # Input comes from STDIN
    data = read_input(sys.stdin)
    for uri in data:
        # Checks if there is a match
        if (uri != None):
            # write the result to STDOUT
            # what we output here will be the input for the
            # Reduce step, i.e. the input for reducer.py
            #
            # tab-delimited;
            print '%s%s%s' % (uri[0], separator, uri[1])

if __name__ == "__main__":
    main()