understand function

[hermann]

I have two files, from which I need to get ip and port information or more generally find what is equal or what is different using mrjob. The following code is a draft of what I'm trying to do.

from mrjob.job import MRJob
import csv
cols='ipv,vvv.vvv.vvv'.split(',') 

def parse_line(line_str):
    return dict(zip(cols,[a.strip() for a in csv.reader([line_str]).next()]))

def parse_ip_address(ip_str):
    ip=ip_str;
    return ip

def parse_port(p_str):
    port=p_str;
    return (port)

class Myclass(MRJob):
    def mapper(self, _, line):
        #parse the line from current CVS form
        p1=parse_line(line)
        #get ip
        ip_address=parse_ip_address(p1['vvv.vvv.vvv'])
        #get port
        port=parse_port(p1['ipv'])
        #yield a key and a value
        yield port,ip_address

    #reducer function
    def reducer(self, key, values):
        yield key

if __name__ == '__main__':
    Myclass.run()