如何在Python的字典理解中创建值列表 [英] How to create a list of values in a dictionary comprehension in Python

问题描述

以一个非常简单的示例为例，它遍历一个句子并创建一个映射{x:y}的字典，其中x是表示单词长度的键，而y是包含以下内容的句子中的单词列表x字母量

Taking a very simple example of looping over a sentence and creating a dictionary which maps {x:y}, where x is a key representing the length of the words and y is a list of words in the sentence that contain x amount of letters

输入:

mywords = "May your coffee be strong and your Monday be short"

预期输出:

{2: ['be', 'be'], 3: ['May', 'and'], 4: ['your', 'your'], 5: ['short'], 6: ['coffee', 'strong', 'Monday']}

尝试创建一个值列表，但每次都覆盖它:

Here's an attempt that creates a list of values but overwrites it each time:

{len(x):[x] for x in mywords.split()}
{2: ['be'], 3: ['and'], 4: ['your'], 5: ['short'], 6: ['Monday']}

是否可以在Python中一行完成此操作?

Is it possible to do this in one line in Python?

推荐答案

可以，您可以使用sorted + groupby，但是看起来并不好.

Sure, you can, using sorted + groupby, but it doesn't look great.

from itertools import groupby
d = dict([(k, list(g)) for k, g in groupby(sorted(mywords.split(), key=len), key=len)])

print(d)
{2: ['be', 'be'],
 3: ['May', 'and'],
 4: ['your', 'your'],
 5: ['short'],
 6: ['coffee', 'strong', 'Monday']}

_{PS，这是我对的答案(使用我为此推荐的defaultdict) href ="https://stackoverflow.com/q/46820551/4909087">原始问题.}

_{P.S., Here's my answer (using defaultdict that I recommend over this) to the original question.}

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