Splitting Lines - Answer to exercise 3

import sys

lines = open( sys.argv[1], "r" ).readlines()

total_premium = 0
nmakes = 0

oldest_age = 0
highest_class = 0
lowest_class = 1000

for i in range( 1, len(lines) ):
    line = lines[i].rstrip()
    words = line.split(",")

    if len(words) >= 4:
        make = words[0]
        car_class = int( words[1] )
        premium = float( words[2] )
        age = words[3]

        nmakes += 1

        total_premium += premium

        if age > oldest_age:
            oldest_make = make
            oldest_age = age

        if car_class > highest_class:
            highest_make = make
            highest_class = car_class
        
        if car_class < lowest_class:
            lowest_make = make
            lowest_class = car_class

avg_premium = total_premium / nmakes

print "The average premium is $%f." % avg_premium
print "The oldest make is %s." % oldest_make
print "The make in the lowest class is %s." % lowest_make
print "The make in the highest class is %s." % highest_make