#!/usr/bin/python

# P2PU - Python Programming 101 - Chapter 10 - Regular Expressions
# Python for Informatics - Chapter 11 - Regular Expressions
# Exercise 11.2

import re

fname = 'mbox.txt'
fhand = open(fname)
revs = list()

for line in fhand:
    line = line.rstrip()
    rev = re.findall('^New Revision: (\d+)', line)
    if len(rev) > 0:
        revs.append(int(rev[0]))

print 'Average revision number: ', float(sum(revs))/len(revs)