本文介绍了在 Python 中迭代分区的处理方法,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
我想知道(在 Python 中)迭代给定大小列表的分区的最佳方法是什么.
I was wondering what the best way is (in Python) to iterate over partitions of a list of a given size.
例如,我们有列表 [1,2,3,4,5]
并且我们想要 k=3
分区.这样做的一个不好的方法是写:
Say, for example, we have the list [1,2,3,4,5]
and we want k=3
partitions. A poor way of doing this would be to write:
lst = [1,2,3,4,5]
for i in range(1,len(lst)):
for j in range(i+1, len(lst)):
print lst[:i], lst[i:j], lst[j:]
这给了
[1], [2], [3,4,5]
[1], [2,3], [4,5]
...
[1,2,3], [4], [5]
但如果我以后想要迭代 k=4
分区,那么我将不得不添加一个级别的 for 循环嵌套,而这在运行时无法完成.理想情况下,我想写这样的东西:
But if I later wanted to iterate over k=4
partitions, then I would have to add a level of for loop nesting, which can't be done at runtime. Ideally, I'd like to write something like:
for part in partitions([1,2,3,4,5], k):
print part
有谁知道最好的方法?
推荐答案
如果没有pairwise
,我会使用和你一样的想法:
I would use the same idea as yours without pairwise
:
from itertools import combinations
def partitions(items, k):
def split(indices):
i=0
for j in indices:
yield items[i:j]
i = j
yield items[i:]
for indices in combinations(range(1, len(items)), k-1):
yield list(split(indices))
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