将python列表分解成多个列表，分别随机排列每个列表 [英] Break python list into multiple lists, shuffle each lists separately

问题描述

假设我按照日期排列在有序列表中.

Let's say I have posts in ordered list according to their date.

[<Post: 6>, <Post: 5>, <Post: 4>, <Post: 3>, <Post: 2>, <Post: 1>]

我想将它们分为3组，并相应地调整列表中的项目.

I want to break them into 3 groups, and shuffle the items inside the list accordingly.

chunks = [posts[x:x+2] for x in xrange(0, len(posts), 2)]

现在，块将返回:

[[<Post: 6>, <Post: 5>], [<Post: 4>, <Post: 3>], [<Post: 2>, <Post: 1>]]

有哪些有效的方法可以随机地将每个列表中的这些项目随机排序? 我可以考虑遍历它们，创建每个列表，但这似乎是重复的...

What are some efficient ways to randomly shuffle these items inside each respective lists? I could think of iterating through them, creating each respective lists but this seems repetitive...

我希望最终输出看起来像:

I want the final output to look something like:

[[<Post: 5>, <Post: 6>], [<Post: 4>, <Post: 3>], [<Post: 1>, <Post: 2>]]

或更好:

[<Post: 5>, <Post: 6>, <Post: 4>, <Post: 3>, <Post: 1>, <Post: 2>]

推荐答案

好的. random.shuffle是就地工作的，因此循环遍历列表元素并将其应用于它们就可以完成第一项工作. 对于展平"，我使用了我最喜欢的技巧:在开始元素为空列表的子列表上应用sum.

Sure. random.shuffle works in-place so looping through list elements and applying it on them does the first job. For the "flattening" I use a favorite trick of mine: applying sum on sublists with start element as empty list.

import random,itertools

chunks = [["Post: 6", "Post: 5"], ["Post: 4", "Post: 3"], ["Post: 2", "Post: 1"]]

# shuffle

for c in chunks: random.shuffle(c)

# there you already have your list of lists with shuffled sub-lists
# now the flattening

print(sum(chunks,[]))                  # or (more complex but faster below)
print(list(itertools.chain(*chunks)))  # faster than sum on big lists

一些结果:

['Post: 5', 'Post: 6', 'Post: 4', 'Post: 3', 'Post: 2', 'Post: 1']
['Post: 6', 'Post: 5', 'Post: 3', 'Post: 4', 'Post: 1', 'Post: 2']

(您说过您想要类似[[<Post: 5>, <Post: 6>, <Post: 4>, <Post: 3>, <Post: 1>, <Post: 2>]](列表中的列表)的内容，但我想这是一个错字:我提供了一个简单而扁平的列表.

(you said you wanted something like [[<Post: 5>, <Post: 6>, <Post: 4>, <Post: 3>, <Post: 1>, <Post: 2>]] (list in a list) but I suppose that's a typo: I provide a simple, flattened list.

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