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python - 如何清空单独列表中列表列表中的所有项目

问题描述

我是 Python 和一般编程的新手，所以也许有一种简单的方法可以轻松做到这一点。到目前为止我写的代码是这样的（我给你所有的上下文代码）：

def prime(n):
    if n > 1:
        for i in range(2, n):
            if n % i == 0:
                return False
    return True


def length(n):
    if len(n) > 5:
        return True
    return False


def list_filter(lista):
    return [x for x in lista if x]


toggle = False
enter_numbers = True
zero_one_neg = True
prime_list = []
lcm_list = []
while enter_numbers:
    nums = list(map(int, input('\nEnter up to five natural numbers greater than 1 separated by commas. Enter at least two if you want to calculate their LCM: ').split(',')))
    for i in range(len(nums)):
        if nums[i] <= 1:
            zero_one_neg = True
            print('\nNo zeroes, ones or negatives. Start over. ')
            if length(nums) and zero_one_neg:
                print('\nNo more than five numbers. Start over. ')
                break
            break
        else:
            zero_one_neg = False
    if length(nums) and not zero_one_neg:
        print('\nNo more than five numbers. Start over. ')
    elif not length(nums) and not zero_one_neg:
        enter_numbers = False
for i in range(len(nums)):
    lcm_list.append([])
    prime_list.append([])
    for j in range(2, nums[i]):
        if nums[i] % j == 0:
            lcm_list[i].append(j)
            if prime(j):
                prime_list[i].append(j)
            toggle = True
    if not toggle:
        print('\n', nums[i], 'is a prime number.')
    if toggle:
        print('\n', nums[i], 'is not a prime number. It\'s prime factors are: ', prime_list[i])
        toggle = False
filtered_lcm_list = list_filter(lcm_list)
filtered_prime_list = list_filter(prime_list)
for i in range(len(filtered_lcm_list)):
    l = list(map(int, filtered_lcm_list[i]))
print(l)
print(filtered_lcm_list)

问题出在本节：

for i in range(len(filtered_lcm_list)):
    full_list = list(map(int, filtered_lcm_list[i]))
print(full_list)
print(filtered_lcm_list)

如果我输入 88,77 我得到这个输出：

Enter up to five natural numbers greater than 1 separated by commas. Enter at least two if you want to calculate their LCM: 88,77

 88 is not a prime number. It's prime factors are:  [2, 11]

 77 is not a prime number. It's prime factors are:  [7, 11]
[7, 11]
[[2, 4, 8, 11, 22, 44], [7, 11]]

Process finished with exit code 0

我想full_list包含所有元素，filtered_lcm_list但不包含列表列表。

标签： pythonlist

解决方案

这个怎么样？

full_list = [int(i) for sub_list in filtered_lcm_list for i in sub_list]

这利用了列表推导，首先遍历包含在 中的列表filtered_lcm_list，然后遍历每个嵌套列表中的元素。

如果您不希望返回重复的数字，您可以使用集合理解：

full_list = {int(i) for sub_list in filtered_lcm_list for i in sub_list]}

并将其转换回列表，list(full_list)如果你愿意的话。

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