Python - randrange() 的空范围 (0,0, 0) 和 ValueError("randrange() 的空范围 (%d,%d, %d)" % (istart, istop, width))

Question

当我运行这个程序时：（python 3.3.1）

import random
import time
from random import randrange
print(' ')
print('I am thinking of a person...')
time.sleep(1)
print('He or she belongs to this group of people:')
people = 'Alice Elise Jack Jill Ricardo David Jane Sacha Thomas'.split()
loop = 0
while loop != 6:
    group = []
    person = randrange(0, len(people))
    personName = people[person]
    int(person)
    group.append(personName)
    del people[person]
    loop = loop + 1

我有时会收到此错误消息：

Traceback (most recent call last):
  File "C:\Users\user\Python\wsda.py", line 132, in <module>
    person = randrange(0, len(people))
  File "C:\Python33\lib\random.py", line 192, in randrange
    raise ValueError("empty range for randrange() (%d,%d, %d)" % (istart, istop,     width))
ValueError: empty range for randrange() (0,0, 0)

基本上我希望它从变量“people”中获取6个随机名称并将其添加到变量“group”中......

这也是一个基于猜谁游戏的更大程序的一部分...有人可以告诉我如何解决这个问题吗？谢谢

Answer 1

people当列表为空（长度为 0）时会发生错误。您可能想测试一下：

>>> import random
>>> random.randrange(0, 0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/mj/Development/Libraries/buildout.python/parts/opt/lib/python2.7/random.py", line 217, in randrange
    raise ValueError, "empty range for randrange() (%d,%d, %d)" % (istart, istop, width)
ValueError: empty range for randrange() (0,0, 0)

如果您需要从列表中添加 6 个随机选择，people最好先打乱列表people，然后将该列表的前 6 个添加到group：

import random

people = 'Alice Elise Jack Jill Ricardo David Jane Sacha Thomas'.split()
random.shuffle(people)
group.extend(people[:6])
people = people[6:]  # remainder, so the 6 picks have been removed

但当然有可能在某个时候你会再次得到一个空列表。

另一种方法是只使用random.sample()：

people = 'Alice Elise Jack Jill Ricardo David Jane Sacha Thomas'.split()
group.extend(random.sample(people, 6))

这只是从列表中随机选择 6 个名称，但people不受影响，并且将来选择的 6 个名称可能会重复名称。