Python列表空格元素删除问题：for循环无法完全清除空格

为什么循环只删了部分空格？ #

在遍历列表的同时直接调用remove()修改列表，会导致列表的索引错位。比如原列表前4个都是空格：

• 第一次循环删第一个空格，列表长度从11变成10，原本的第二个空格移到索引0的位置
• 下一次循环会取原索引1的元素（也就是原本的第三个空格），直接跳过了现在索引0的空格
• 按这个逻辑循环下来，开头会剩下一个没被遍历到的空格，后面的空格也因为同样的原因被跳过部分

三种可行的解决方法 #

方法1：遍历列表的副本 #

遍历原列表的拷贝，这样修改原列表不会影响遍历的过程：

mylist = [" "," "," "," ","oho","abcd","1234",1234," "," ","omg"]
for i in mylist.copy():
    if i == ' ':
        mylist.remove(i)
print(mylist)  # 输出：['oho', 'abcd', '1234', 1234, 'omg']

方法2：使用列表推导式（推荐） #

直接生成过滤后的新列表，这是Python中处理这类需求最简洁高效的方式：

mylist = [" "," "," "," ","oho","abcd","1234",1234," "," ","omg"]
mylist = [item for item in mylist if item != ' ']
print(mylist)

方法3：倒序遍历原列表 #

倒着遍历列表的索引，删除元素时不会影响前面还没遍历到的元素：

mylist = [" "," "," "," ","oho","abcd","1234",1234," "," ","omg"]
for i in range(len(mylist)-1, -1, -1):
    if mylist[i] == ' ':
        del mylist[i]
print(mylist)

内容的提问来源于stack exchange，提问作者Not0_0Parsa