本文介绍了一些内置在python中填充列表的功能的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个< N ,我想用一个值将其填充到大小N.
I have a list of size < N and I want to pad it up to the size N with a value.
当然,我可以使用类似以下的内容,但是我觉得应该错过了一些东西:
Certainly, I can use something like the following, but I feel that there should be something I missed:
>>> N = 5
>>> a = [1]
>>> map(lambda x, y: y if x is None else x, a, ['']*N)
[1, '', '', '', '']
推荐答案
a += [''] * (N - len(a))
或者如果您不想就地更改a
or if you don't want to change a
in place
new_a = a + [''] * (N - len(a))
您始终可以创建list的子类,并随便调用该方法
you can always create a subclass of list and call the method whatever you please
class MyList(list):
def ljust(self, n, fillvalue=''):
return self + [fillvalue] * (n - len(self))
a = MyList(['1'])
b = a.ljust(5, '')
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