如何使用 python itertools.groupby() 按第一个字符对字符串列表进行分组？
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How can I use python itertools.groupby() to group a list of strings by their first character?
提问by Adam Ziolkowski
I have a list of strings similar to this list:
我有一个类似于此列表的字符串列表：
tags = ('apples', 'apricots', 'oranges', 'pears', 'peaches')
How should I go about grouping this list by the first character in each string using itertools.groupby()? How should I supply the 'key' argument required by itertools.groupby()?
我应该如何使用 itertools.groupby() 按每个字符串中的第一个字符对该列表进行分组？我应该如何提供 itertools.groupby() 所需的“key”参数？
回答by Ignacio Vazquez-Abrams
groupby(sorted(tags), key=operator.itemgetter(0))
回答by Pratik Deoghare
You might want to create dictafterwards:
您可能想在dict之后创建：
from itertools import groupby
d = {k: list(v) for k, v in groupby(tags, key=lambda x: x[0])}
回答by SilentGhost
>>> for i, j in itertools.groupby(tags, key=lambda x: x[0]):
print(i, list(j))
a ['apples', 'apricots']
o ['oranges']
p ['pears', 'peaches']
回答by ghostdog74
just another way,
只是另一种方式，
>>> from collections import defaultdict
>>> t=defaultdict(list)
>>> for items in tags:
... t[items[0]].append(items)
...
>>> t
defaultdict(<type 'list'>, {'a': ['apples', 'apricots'], 'p': ['pears', 'peaches'], 'o': ['oranges']})
