Timeit

This line will run this code a set number of times (1,000,000 by default!) and report the total time. The first parameter on this line is the code that you want to time. The second parameter is a special one-time setup. Since we are timing a user-defined function, we have to first import this function before timeit can call it. The last parameter is the number of times you want the statement to run.

模块的第一个参数为要执行计时的语句（statement）。按字符串的形式传入要执行的代码。第二个参数setup用于构建代码环境，可以用来导入需要的模块。最后的number指定了运行的次数。

import timeit
def read_to_list(user_input):
    with open('4sbwinners.txt','r') as f:
        winners = list(f)

    return winners[user_input-1].strip()

def sequential_access(user_input):
    with open('4sbwinners.txt','r') as f:
    # Reads (and dumps) lines until we get to the user selection
        for i in range(0,user_input-1):
            f.readline()

        winner = f.readline()

    return winner.strip()

user_input = int(raw_input('Enter Super Bowl #: '))

while user_input < 1 or user_input > 4:
    user_input = int(raw_input('Enter Super Bowl #: '))

seq_time = timeit.timeit('sequential_access({})'.format(user_input), \
    'from __main__ import sequential_access',number=100000)

list_time = timeit.timeit('read_to_list({})'.format(user_input), \
    'from __main__ import read_to_list',number=100000)

if seq_time < list_time:
    pct = (list_time - seq_time) / seq_time
    print 'Sequential access is {:.1f}% faster.'.format(pct * 100)
else:
    pct = (seq_time - list_time) / list_time
    print 'List access is {:.1f}% faster.'.format(pct * 100)

Notice the following two sample runs:

Enter Super Bowl #: 1
Sequential access is 7.1% faster.

Enter Super Bowl #: 4
Sequential access is 2.2% faster.