python timeit 测试单条语句或者函数执行时间

有时候需要比较两个语句的执行时间，例如 a_list = [i for i in range(100)] 和 a_list = list(range(100))

不知道 timeit 之前我是这样写的：

def test_one(number):
    for i in range(number):
        a_list = [i for i in range(100)]


def test_two(number):
    for i in range(number):
        a_list = list(range(100))


if __name__ == '__main__':
    start = time.time()
    test_one(10000)
    end = time.time()
    print('{}: {}'.format(test_one.__name__, end - start))

    start = time.time()
    test_two(10000)
    end = time.time()
    print('{}: {}'.format(test_two.__name__, end - start))
    

output
test_one: 0.053299665451049805
test_two: 0.01783156394958496

接触到了 timeit 之后是这样的:

import timeit

lang_one = '[i for i in range(100)]'
lang_two = 'list(range(100))'
print(timeit.timeit(lang_one, 'from __main__ import lang_one', number=10000))
print(timeit.timeit(lang_two, 'from __main__ import lang_two', number=10000))

output:
0.032601056998828426
0.009418976005690638

timeit.timeit()

• 参数 stmt : 要测试的语句的字符串
• 参数 setup : 要测试语句的导入语句，from __main__ import lang_one，正在执行的文件的文件名为 __main__
• 参数 number : 语句执行的次数

测试函数 执行时间把语句改成函数名，导入语句换成函数的导入语句：

def test():
    lang_one = [i for i in range(100)]
    lang_two = list(range(100))


lang_one = '[i for i in range(100)]'
lang_two = 'list(range(100))'

print(timeit.timeit(lang_one, 'from __main__ import lang_one', number=10000))
print(timeit.timeit(lang_two, 'from __main__ import lang_two', number=10000))
print(timeit.timeit('test()', 'from __main__ import test', number=10000))
print(timeit.timeit(test, 'from __main__ import test', number=10000))

output:
0.03310484399844427
0.009990048994950484
0.04418463000183692
0.04479162200004794