Python中多个级别的“collection.defaultdict” [英] Multiple levels of 'collection.defaultdict' in Python
问题描述
collections.defaultdict
提供的可能性和速度。我已经让他们成功使用了。 现在我想实现三个级别的字典,两个顶级的字典是 defaultdict
,最低的一个是 int
。我没有找到适当的方法来做到这一点。这是我的尝试:
从集合import defaultdict
d = defaultdict(defaultdict)
a = [( (key2,{a1:32,a2:55}),
(key3 ,{a1:43,a2:44})]
在我的a:
d [i [0]] = i [1]
现在这样做,但以下是所需的行为,不会:
d [key4] [a1] + 1
我怀疑我应该声明第二级 defaultdict
的类型是 int
,但我没有没有找到在哪里或如何这样做。
首先我使用 defaultdict
的原因是避免不必为每个新密钥初始化字典。
任何更优雅的建议?
感谢pythoneers! / p>
使用:
d = defaultdict(lambda:defaultdict(int))
每当有一个新的 defaultdict(int)
新密钥在 d
中访问。
Thanks to some great folks on SO, I discovered the possibilities offered by collections.defaultdict
, notably in readability and speed. I have put them to use with success.
Now I would like to implement three levels of dictionaries, the two top ones being defaultdict
and the lowest one being int
. I don't find the appropriate way to do this. Here is my attempt:
from collections import defaultdict
d = defaultdict(defaultdict)
a = [("key1", {"a1":22, "a2":33}),
("key2", {"a1":32, "a2":55}),
("key3", {"a1":43, "a2":44})]
for i in a:
d[i[0]] = i[1]
Now this works, but the following, which is the desired behavior, doesn't:
d["key4"]["a1"] + 1
I suspect that I should have declared somewhere that the second level defaultdict
is of type int
, but I didn't find where or how to do so.
The reason I am using defaultdict
in the first place is to avoid having to initialize the dictionary for each new key.
Any more elegant suggestion?
Thanks pythoneers!
Use:
d = defaultdict(lambda: defaultdict(int))
This will create a new defaultdict(int)
whenever a new key is accessed in d
.
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