遍历Python中的列表 [英] Looping over a list in Python

问题描述

我有一个带有子列表的列表.我想打印所有长度等于3的子列表.

I have a list with sublists in it. I want to print all the sublists with length equal to 3.

我正在python中执行以下操作:

I am doing the following in python:

for x in values[:]:
    if len(x) == 3:
        print(x)

values是原始列表.上面的代码是否为每个x值打印每个长度等于3的子列表?我只想显示一次length == 3的子列表.

values is the original list. Does the above code print every sublist with length equal to 3 for each value of x? I want to display the sublists where length == 3 only once.

问题已解决.问题出在Eclipse编辑器上.我不明白原因，但是当我运行循环时，它只显示列表的一半.

The problem is solved. The problem is with the Eclipse editor. I don't understand the reason, but it is displaying only half of my list when I run my loop.

我在Eclipse中需要更改任何设置吗?

Are there any settings I have to change in Eclipse?

推荐答案

尝试一下，

x in mylist比x in mylist[:]更好并且更具可读性，并且len(x)应该等于3.

x in mylist is better and more readable than x in mylist[:] and your len(x) should be equal to 3.

>>> mylist = [[1,2,3],[4,5,6,7],[8,9,10]]
>>> for x in mylist:
...      if len(x)==3:
...        print x
...
[1, 2, 3]
[8, 9, 10]

或者如果您需要更多的Python语言，请使用列表理解

or if you need more pythonic use list-comprehensions

>>> [x for x in mylist if len(x)==3]
[[1, 2, 3], [8, 9, 10]]
>>>

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