在python中填充具有特定值的列表 [英] Padding a list in python with particular value

问题描述

可能重复:
一些内置在python中填充列表的

Possible Duplicate:
Some built-in to pad a list in python

我有一个方法将返回包含4个元素的列表(实例变量). 另一种方法是将值分配给列表.

I have a method that will return a list (instance variable) with 4 elements. Another method is used to assign values to the list.

但是目前我不能保证列表被要求包含4个元素，所以我想用0填充它.

But at the moment I can't guarantee that the list has 4 elements when it's asked for, so I want to fill it up with 0's.

除了说一个循环外，是否有其他方法可以用0填充它?

Is there a way to fill it with 0's other than say a loop?

for i in range(4 - len(self.myList)):
   self.myList.append(0)

推荐答案

self.myList.extend([0] * (4 - len(self.myList)))

这在填充整数时有效.不要对易变的对象执行此操作.

This works when padding with integers. Don't do it with mutable objects.

另一种可能性是:

self.myList = (self.myList + [0] * 4)[:4]

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