无限嵌套的 defaultdict 是否有标准类?

Is there a standard class for an infinitely nested defaultdict?(无限嵌套的 defaultdict 是否有标准类?)

问题描述

有谁知道 Python 中是否有用于无限嵌套字典的标准类?

我发现自己在重复这种模式:

d = defaultdict(lambda: defaultdict(lambda: defaultdict(int)))d['abc']['def']['xyz'] += 1
如果我想添加另一层"(例如d['abc']['def']['xyz']['wrt'])，我必须定义另一个嵌套defaultdicts.
为了概括这种模式，我编写了一个简单的类来覆盖 __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 += 0.24d['abc']['def']['xyz'].total += 1d['abc']['def']['xyz']['wrt'].count += 0.143d['abc']['def']['xyz']['wrt'].total += 1
但是，有没有人知道这个想法的预先存在的实现?我试过谷歌搜索，但我不确定这会叫什么.
 解决方案 
您可以从 defaultdict 派生以获得您想要的行为:
class InfiniteDict(defaultdict):def __init__(self):defaultdict.__init__(self, self.__class__)类计数器(InfiniteDict):def __init__(self):InfiniteDict.__init__(self)self.count = 0self.total = 0定义显示(自我):打印%i 出 %i" % (self.count, self.total)
这个类的用法如下:
<预><代码>>>>d = 计数器()>>>d[1][2][3].total = 5>>>d[1][2][3].show()0 分(共 5 分)>>>d[5].show()0 出 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.

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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