list.remove() 没有删除所有实例

Question

我面临着相当奇怪的列表情况。在这种情况下，Python 似乎对删除哪些零非常有选择性：

count = 0

a = ["a",0,0,"b",None,"c","d",0,1,False,0,1,0,3,[],0,1,9,0,0,{},0,0,9]

for x in a:

    if x == 0:

        a.remove(x)

        count += 1

print(a, count)

仅删除 10 个零中的 6 个。为什么 ？

Answer 1

一个更好的解决方案是只创建一个不包含 0 的新列表：b = [x for x in a if x != 0]count = len(a) - len(b)

Answer 2

要解决评论中的人描述的问题，您可以执行以下操作：count = 0a = ["a",0,0,"b",None,"c","d",0,1,False,0,1,0,3,[],0,1,9,0,0,{},0,0,9]for x in a.copy():    if x == 0:        a.remove(x)        count += 1print(a, count)然后，您将遍历原始a，同时0在遇到它时将其减少。警告：>>> False == 0True

Answer 3

x = ["a",0,0,"b",None,"c","d",0,1,False,0,1,0,3,[],0,1,9,0,0,{},0,0,9]list(filter(lambda a: a != 0, x))输出['a', 'b', None, 'c', 'd', 1, 1, 3, [], 1, 9, {}, 9]