将深度很大的嵌套字典(森林)写入文本文件 [英] Writing nested dictionary (forest) of a huge depth to a text file

问题描述

我有一个巨大的深度字典，代表森林(许多非二叉树)，我要处理森林并创建一个具有森林所有可能关系的文本文件，例如给出字典:

I have a huge depth dictionary that represents forest (many non-binary trees) which I want to process the forest and create a text file with all possible relations of the forest, e.g. given the dictionary:

{'a': {'b': {'c': {}, 'd': {}}, 'g': {}}}

生成的文本文件如下所示:

the generated text file will look like:

a b c
a b d
a g

请注意，嵌套字典很大，并且递归对其进行迭代会导致内存运行时错误.

Note that the nested dictionary is big and iterating over it recursively is makes a memory run-time error.

我尝试做的是将字典递归转换为列表列表，这会产生运行时错误.代码:

What I tried doing is converting the dictionary into a list of lists recursively which yields a run-time error. The code:

def return_list(forest):
    for ent in forest.keys():
        lst = [new_ent] + grab_children(forest[ent])
        yield lst

def grab_children(father):
    local_list = []
    for key, value in father.items():
        local_list.append(new_key)
        local_list.extend(grab_children(value))
    return local_list

错误:在比较中超过了最大递归深度" RuntimeError

The error: "maximum recursion depth exceeded in comparison" RuntimeError

推荐答案

无递归，带有生成器和蹦床(写入文件):

Without recursion, with generator and trampoline (with writing to file):

data = {'a': {'b': {'c': {}, 'd': {}}, 'g': {}}}


def write_dict(d, s=(), f_out=None):
    if len(d) == 0:
        if f_out:
            f_out.write(' '.join(s) + '\n')
        return

    for k, v in reversed(list(d.items())):
        yield write_dict, v, s + (k, ), f_out


with open('data_out.txt', 'w') as f_out:

    stack = [write_dict(data, f_out=f_out)]

    while stack:
        try:
            v = next(stack[-1])
        except StopIteration:
            del stack[-1]
            continue

        stack.insert(-1, v[0](v[1], v[2], v[3]))

文件包含:

a b c
a b d
a g

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