在嵌套字典python中搜索值

Question

搜索一个值并获取父词典名称（键）：

Dictionary = {dict1:{
        'part1': {
            '.wbxml': 'application/vnd.wap.wbxml',
            '.rl': 'application/resource-lists+xml',    
        },
        'part2':
            {'.wsdl': 'application/wsdl+xml',
            '.rs': 'application/rls-services+xml',
            '.xop': 'application/xop+xml',
            '.svg': 'image/svg+xml',
            },
        'part3':{...}, ...

   dict2:{
          'part1': {    '.dotx': 'application/vnd.openxmlformats-..'                           
            '.zaz': 'application/vnd.zzazz.deck+xml',
            '.xer': 'application/patch-ops-error+xml',}  
          },
          'part2':{...},
          'part3':{...},...

    },...

在以上字典中，我需要搜索类似的值："image/svg+xml"。其中，字典中没有任何值重复。如何搜索"image/svg+xml"？因此它应该返回字典中的父键{dict1:"part2" }。

请注意 ：解决方案应在 未修改的情况下 适用 于 Python 2.7和Python 3.3。

Answer 1

这是对嵌套dict的迭代遍历，还可以跟踪导致特定点的所有键。因此，一旦您在字典中找到正确的值，您就已经具有获取该值所需的键。

如果将以下代码放在.py文件中，则它们将按原样运行。该find_mime_type(...)函数返回的键序列将使您从原始词典转到所需的值。该demo()功能显示了如何使用它。

d = {'dict1':
         {'part1':
              {'.wbxml': 'application/vnd.wap.wbxml',
               '.rl': 'application/resource-lists+xml'},
          'part2':
              {'.wsdl': 'application/wsdl+xml',
               '.rs': 'application/rls-services+xml',
               '.xop': 'application/xop+xml',
               '.svg': 'image/svg+xml'}},
     'dict2':
         {'part1':
              {'.dotx': 'application/vnd.openxmlformats-..',
               '.zaz': 'application/vnd.zzazz.deck+xml',
               '.xer': 'application/patch-ops-error+xml'}}}


def demo():
    mime_type = 'image/svg+xml'
    try:
        key_chain = find_mime_type(d, mime_type)
    except KeyError:
        print ('Could not find this mime type: {0}'.format(mime_type))
        exit()
    print ('Found {0} mime type here: {1}'.format(mime_type, key_chain))
    nested = d
    for key in key_chain:
        nested = nested[key]
    print ('Confirmation lookup: {0}'.format(nested))


def find_mime_type(d, mime_type):
    reverse_linked_q = list()
    reverse_linked_q.append((list(), d))
    while reverse_linked_q:
        this_key_chain, this_v = reverse_linked_q.pop()
        # finish search if found the mime type
        if this_v == mime_type:
            return this_key_chain
        # not found. keep searching
        # queue dicts for checking / ignore anything that's not a dict
        try:
            items = this_v.items()
        except AttributeError:
            continue  # this was not a nested dict. ignore it
        for k, v in items:
            reverse_linked_q.append((this_key_chain + [k], v))
    # if we haven't returned by this point, we've exhausted all the contents
    raise KeyError


if __name__ == '__main__':
    demo()

输出：

在此处找到image / svg + xml MIME类型：[‘dict1’，’part2’，’。svg’]

确认查询：image / svg + xml