Python中的无限嵌套字典 [英] Infinitely Nested Dictionary in Python

问题描述

有没有人知道Python中有无限嵌套的字典是否有标准类？

我发现自己重复这种模式：

  d = defaultdict（lambda：defaultdict（lambda：defaultdict（int）））
d ['abc'] ['def'] ['xyz '] + = 1 
  

如果我要添加另一层（例如 d ['abc'] ['def'] ['xyz'] ['wrt'] ），我必须定义另一个嵌套的默认值。

为了概括这种模式，我写了一个简单的类，它覆盖 __ getitem __ 以自动创建下一个嵌套字典。

例如

  d = InfiniteDict（（'count'，0），（'total'，0） ）
d ['abc'] ['def'] ['xyz']。count + = 0.24 
d ['abc'] ['def'] ['xyz'] total + = 1 
d ['abc'] ['def'] ['xyz'] ['wrt']。count + = 0.143 
d ['abc'] ['def'] ['xyz'] ['wrt '] .total + = 1 
  

但是，有没有人知道这个想法的预先实现？我试过谷歌，但我不知道这将被称为什么。

解决方案

你可以从 defaultdict 以获取所需的行为：

  class InfiniteDict（defaultdict）：
 def __init __（self）：
 defaultdict .__ init __（self，self .__ class__）
 
类计数器（InfiniteDict）：
 def __init __（self）：
 InfiniteDict .__ init __（self）
 self.count = 0 
 self.total = 0 
 
 def show（self）：
 print％i out of％i ％（self.count，self.total）
  

此类的用法如下所示： / p>

 >>> d =计数器（）
>>> d [1] [2] [3] .total = 5 
>>>> d [1] [2] [3] .show（）
 0 out of 5 
>>> d [5] .show（）
 0 out of 0 
  

Does anyone know if there's a standard class for an infinitely nestable dictionary in Python?

I'm finding myself repeating this pattern:

d = defaultdict(lambda: defaultdict(lambda: defaultdict(int)))
d['abc']['def']['xyz'] += 1

If I want to add "another layer" (e.g. d['abc']['def']['xyz']['wrt']), I have to define another nesting of defaultdicts.

To generalize this pattern, I've written a simple class that overrides __getitem__ to automatically create the next nested dictionary.

e.g.

d = InfiniteDict(('count',0),('total',0))
d['abc']['def']['xyz'].count += 0.24
d['abc']['def']['xyz'].total += 1
d['abc']['def']['xyz']['wrt'].count += 0.143
d['abc']['def']['xyz']['wrt'].total += 1

However, does anyone know of a pre-existing implementation of this idea? I've tried Googling, but I'm not sure what this would be called.

解决方案

You can derive from defaultdict to get the behavior you want:

class InfiniteDict(defaultdict):
   def __init__(self):
      defaultdict.__init__(self, self.__class__)

class Counters(InfiniteDict):
   def __init__(self):
      InfiniteDict.__init__(self)                                               
      self.count = 0
      self.total = 0

   def show(self):
      print "%i out of %i" % (self.count, self.total)

Usage of this class would look like this:

>>> d = Counters()
>>> d[1][2][3].total = 5
>>> d[1][2][3].show()
0 out of 5
>>> d[5].show()
0 out of 0

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