Python - 如何使用while循环和for循环从列表中随机删除一个项目直到列表为空

Question

I have been trying to remove a random item from a list using a while-loop and for-loop. For the while-loop, it should print it to the console until the list -days- is empty.

Here is my code thus far-

while-loop:

days = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday']

while len(days) > 0:
    days = days.pop(0)

for-loop:

for day in range(len(days)):
    day = days.pop(0)

output: for-loop:

AttributeError: 'str' object has no attribute 'pop'

I am a novice programmer and I am struggling to correct this issue. Is there a way to pop items from the while loop? Can someone explain the attribute error and why I am getting this message?

Answer 1

if you want to remove randomly

days = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday']

from random import randrange
while len(days) > 0:
    index=randrange(0,len(days))
    days.pop(index)
    print(days)

print('End')

Answer 2

Your first loop is the right way to do it. but you are overwriting the list with the first element. You want

while days:
    day = days.pop(0)

The for loop is not good practice. It is dangerous to modify a list while you are iterating through it. Think about it. First time through the loop, "day" is 0. You pop element 0. Now, the element that used to be [1] is in the [0] slot, but when you loop again, day will be 1 and your numbering is off.

And AGAIN, you are overwriting the loop variable ( day ) with the result of the pop. Be careful with your variable names.

Answer 3

To remove randomly you can use numpy to generate a random number, and then use.pop() to remove an item from the list and print it at the same time:

import numpy as np
days = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday']

while days:
    index = int(np.round((np.random.rand(1)-0.5)*len(days)))
    print(days.pop(index))