Python:循环中的del

Question

问题:

test1 = [1, 2, 3]
for i in range(len(test1)): #Want to do the below for every element in test1 
    print(test1[i])
    if test1[i] % 2 == 0: #if the element meets certain conditions, it gets deleted
        del test1[i] 
        #The thing in test1 gets deleted, but the range gets not updated,
        #and i iterates nonetheless, so 1 element gets ignored,
        #and in the end, I get "list index out of range"

(在实际代码中，if 语句要多得多，而且数组中的东西不是整数而是对象？!一个类的，所以列表理解更多-嗯...)

我想出了这个方法:

test1 = [1, 2, 3]
i = 0
x = len(test1)
while i < x:
    print(test1[i])
    if test1[i] % 2 == 0:
        del test1[i]
        x -= 1
        i -= 1
    i += 1

但是如您所见，这多了 5 行(并且对于每个 del，我必须添加 2 行...)，丑陋且烦人。有没有更好的方法来做这样的事情？比如，直接进入 for 循环、更新范围并让您选择 i 或其他内容的重做命令？

Answer 1

使用列表理解

类似的东西:

list = [x for x in list if x % 2 == 1] # Keep anything that is not even
for thing in list:
    print(thing)

这将创建一个包含与条件匹配的任何内容的新列表。 然后打印新列表

>>> test1 = [1,2,3]
>>> list = [x for x in test1 if x % 2 is 1]
>>> print(list)
[1, 3]