python-测量功能时间

Question

我在测量函数的时间时遇到问题。

我的函数是 "linear search":

def linear_search(obj, item,):
    for i in range(0, len(obj)):
        if obj[i] == item:
        return i
    return -1

然后我创建了另一个函数来测量时间 100 次并将所有结果添加到列表中：

def measureTime(a):
    nl=[]
    import random
    import time
    for x in range(0,100): #calculating time
        start = time.time() 
        a   
        end =time.time()
        times=end-start
        nl.append(times)
    return nl

当我使用 measureTime(linear_search(list,random.choice(range(0,50)))) 时，函数总是 returns [0.0].

什么会导致这个问题？谢谢。

Answer 1

看看下面的例子，不知道你到底想达到什么目的所以我猜了;)

import random
import time

def measureTime(method, n, *args):
    start = time.time()
    for _ in xrange(n):
        method(*args)
    end = time.time()
    return (end - start) / n

def linear_search(lst, item):
    for i, o in enumerate(lst):
        if o == item:
            return i
    return -1

lst = [random.randint(0, 10**6) for _ in xrange(10**6)]
repetitions = 100
for _ in xrange(10):
    item = random.randint(0, 10**6)
    print 'average runtime =', 
    print measureTime(linear_search, repetitions, lst, item) * 1000, 'ms'

Answer 2

你实际上是将 linear_search 的结果传递给函数 measureTime，你需要传递函数和参数而不是让它们在 measureTime 函数中执行，就像@martijnn2008回答

或者更明智的做法是，您可以考虑使用 timeit 模块来完成您的工作

from functools import partial
import timeit
def measureTime(n, f, *args):
    # return average runtime for n number of times
    # use a for loop with number=1 to get all individual n runtime
    return timeit.timeit(partial(f, *args), number=n)

# running within the module
measureTime(100, linear_search, list, random.choice(range(0,50)))

# if running interactively outside the module, use below, lets say your module name mymodule
mymodule.measureTime(100, mymodule.linear_search, mymodule.list, mymodule.random.choice(range(0,50)))

python-测量功能时间

python-measure function time

python

time

function

measure