在深度嵌套的字典中查找键 [英] Find a key inside a deeply nested dictionary

问题描述

我有很多嵌套的字典，我试图找到嵌套在某个地方的某个键.

I have a lot of nested dictionaries, I am trying to find a certain key nested inside somewhere.

例如此键称为水果".如何找到此键的值?

e.g. this key is called "fruit". How do I find the value of this key?

推荐答案

@Håvard的递归解决方案可能会好起来的……除非嵌套级别太高，然后得到RuntimeError: maximum recursion depth exceeded.为了解决这个问题，您可以使用递归删除的常用技术:保留您自己要检查的项目堆栈(作为您控制下的列表).即:

@Håvard's recursive solution is probably going to be OK... unless the level of nesting is too high, and then you get a RuntimeError: maximum recursion depth exceeded. To remedy that, you can use the usual technique for recursion removal: keep your own stack of items to examine (as a list that's under your control). I.e.:

def find_key_nonrecursive(adict, key):
  stack = [adict]
  while stack:
    d = stack.pop()
    if key in d:
      return d[key]
    for k, v in d.iteritems():
      if isinstance(v, dict):
        stack.append(v)

这里的逻辑与递归答案非常接近(除了以正确的方式检查dict ；-)，明显的例外是递归调用被while循环和.pop替换，并且.append在显式堆栈列表stack上的操作.

The logic here is quite close to the recursive answer (except for checking for dict in the right way;-), with the obvious exception that the recursive calls are replaced with a while loop and .pop and .append operations on the explicit-stack list, stack.

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