python - 具有随机列表的 timeit 函数

Question

尝试计算对随机列表进行排序所需的时间:

import random
import timeit
randoms = random.sample(xrange(100), 10)

print randoms 
timeit.timeit('sorted(r)',setup = 'r = random.sample(xrange(100), 10)')

错误:

Traceback (most recent call last):
  File "C:/Users/Arthur/Desktop/Dropbox/uni stuff/cs/python/theory hmwk/random.py", line 6, in <module>
    timeit.timeit('sorted(r)',setup = 'r = random.sample(xrange(100), 10)')
  File "C:\Python27\lib\timeit.py", line 230, in timeit
    return Timer(stmt, setup, timer).timeit(number)
  File "C:\Python27\lib\timeit.py", line 195, in timeit
    timing = self.inner(it, self.timer)
  File "<timeit-src>", line 3, in inner
NameError: global name 'random' is not defined

Answer 1

您需要在设置字符串中显式导入random:

timeit.timeit('sorted(r)',setup = 'import random; r = random.sample(xrange(100), 10)')
#                                  ^^^^^^^^^^^^^

timeit.timeit 不会自动将名称拉入设置字符串，以避免意外扭曲测试结果(如果它导入了您不想要的名称怎么办？)