Python递归打印嵌套哈希

Question

我想在Python中打印嵌套哈希,由此:

example_dict = {
    'key1' : 'value1',
    'key2' : {
        'key2a': 'value2a'
    },
    'key3' : {
        'key3a': {
            'key3aa': 'value3aa',
            'key3ab': 'value3ab',
            'key3ac': 'value3ac'
        },
        'key3b': [
            'value3b1',
            'value3b2'
        ]
    },
}

这样的事情:

key1 value1
key2 key2a value2a
key3 key3a key3aa value3aa
key3 key3a key3ab value3ab
key3 key3a key3ac value3ac
key3 key3b value3b1
key3 key3b value3b2

我对Python并不熟悉,几个小时后我仍然陷入困境.

我目前正在研究这个功能:

def recursive(src, res, line = ''):
    if isinstance(src, dict):
        for key, value in src.items():
            line += str(' ' + key)
            recursive(value, res, line)
    elif isinstance(src, list):
        for litem in src:
            recursive(litem, res, line)
    else:
        line += str(' ' + str(src))
        res.append(line)

我正在尝试将每行添加到列表中以便以后能够使用它,但我认为我没有使用我的共享变量(行)的正确方法,因为在每个字典中,递归调用是用另一个dict键来自相同的深度,所以我得到了这个:

 key3 key3a key3aa value3aa
 key3 key3a key3aa key3ac value3ac
 key3 key3a key3aa key3ac key3ab value3ab
 key3 key3a key3b value3b1
 key3 key3a key3b value3b2
 key3 key2 key2a value2a
 key3 key2 key1 value1

什么是Pythonic方法呢？

Answer 1

使用生成器(yield语句),您可以递归地执行以下操作:

码:

def recursive(src, so_far=()):
    if isinstance(src, dict):
        for key, value in src.items():
            yield from recursive(value, so_far + (key,))
    elif isinstance(src, list):
        for item in src:
            yield from recursive(item, so_far)
    else:
        yield ' '.join(so_far + (src,))

需要注意的一点是需要从递归的生成器中重新生成结果.这是通过以下方式完成的:

yield from recursive(item, so_far)

这相当于:

for i in recursive(item, so_far):
    yield i

测试代码:

example_dict = {
    'key1': 'value1',
    'key2': {
        'key2a': 'value2a'
    },
    'key3': {
        'key3a': {
            'key3aa': 'value3aa',
            'key3ab': 'value3ab',
            'key3ac': 'value3ac'
        },
        'key3b': [
            'value3b1',
            'value3b2'
        ]
    },
}

for line in recursive(example_dict):
    print(line)

结果:

key1 value1
key2 key2a value2a
key3 key3a key3aa value3aa
key3 key3a key3ab value3ab
key3 key3a key3ac value3ac
key3 key3b value3b1
key3 key3b value3b2