python删除列表元素_如何在Python中的for循环中删除列表元素？

I have a list

a = ["a", "b", "c", "d", "e"]

I want to remove elements in this list in a for loop like below:

for item in a:

print item

a.remove(item)

But it doesn't work. What can I do?

解决方案

You are not permitted to remove elements from the list while iterating over it using a for loop.

The best way to rewrite the code depends on what it is you're trying to do.

For example, your code is equivalent to:

for item in a:

print item

a[:] = []

Alternatively, you could use a while loop:

while a:

print a.pop(0)

I'm trying to remove items if they match a condition. Then I go to next item.

You could copy every element that doesn't match the condition into a second list:

result = []

for item in a:

if condition is False:

result.append(item)

a = result

Alternatively, you could use filter or a list comprehension and assign the result back to a:

a = filter(lambda item:... , a)

or

a = [item for item in a if ...]

where ... stands for the condition that you need to check.