如何在 Python 中的这个嵌套字典中搜索特定键?

How can I search for specific keys in this nested dictionary in Python?(如何在 Python 中的这个嵌套字典中搜索特定键?)

问题描述

我是编程新手，我正在尝试从亚马逊 MWS API 中提取值.它返回我见过的最大的嵌套字典，但我无法弄清楚如何遍历它以找到我需要的值.

I am new to programming and I'm trying to extract values from the Amazon MWS API. It returns the biggest nested dictionary I've seen and I'm having trouble figuring out how to loop through it to find the value I need.

示例:

{'Products': {'Product': {'AttributeSets': {'ItemAttributes': {'Binding': {'value': 'Video '
                                                                                'Game'},
                                                           'Brand': {'value': 'Nintendo'},
                                                           'Color': {'value': 'blue'},
                                                           'ESRBAgeRating': {'value': 'Everyone'},
                                                           'HardwarePlatform': {'value': 'Android/iOS'},
                                                           'IsAdultProduct': {'value': 'false'},
                                                           'ItemDimensions': {'Height': {'Units': {'value': 'inches'},
                                                                                         'value': '5.00'},
                                                                              'Length': {'Units': {'value': 'inches'},
                                                                                         'value': '5.00'},
                                                                              'Weight': {'Units': {'value': 'pounds'},
                                                                                         'value': '0.10'},
                                                                              'Width': {'Units': {'value': 'inches'},
                                                                                        'value': '2.00'}},
                                                           'Label': {'value': 'Nintendo'},
                                                           'Languages': {'Language': {'Name': {'value': 'english'},
                                                                                      'Type': {'value': 'Unknown'}}},
                                                           'ListPrice': {'Amount': {'value': '34.99'},
                                                                         'CurrencyCode': {'value': 'USD'}},
                                                           'Manufacturer': {'value': 'Nintendo'},
                                                           'Model': {'value': 'PMCAPBAA'},
                                                           'OperatingSystem': [{'value': 'Not '
                                                                                         'Machine '
                                                                                         'Specific'},
                                                                               {'value': 'Android/iOS'}],
                                                           'PackageDimensions': {'Height': {'Units': {'value': 'inches'},
                                                                                            'value': '1.00'},
                                                                                 'Length': {'Units': {'value': 'inches'},
                                                                                            'value': '5.10'},
                                                                                 'Weight': {'Units': {'value': 'pounds'},
                                                                                            'value': '0.04'},
                                                                                 'Width': {'Units': {'value': 'inches'},
                                                                                           'value': '2.90'}},
                                                           'PackageQuantity': {'value': '1'},
                                                           'PartNumber': {'value': 'PMCAPBAA'},
                                                           'Platform': [{'value': 'Not '
                                                                                  'Machine '
                                                                                  'Specific'},
                                                                        {'value': 'Android'},
                                                                        {'value': 'iOS'},
                                                                        {'value': 'Nintendo '
                                                                                  'Wii'}],
                                                           'ProductGroup': {'value': 'Video '
                                                                                     'Games'},
                                                           'ProductTypeName': {'value': 'VIDEO_GAME_ACCESSORIES'},
                                                           'Publisher': {'value': 'Nintendo'},
                                                           'ReleaseDate': {'value': '2016-09-16'},
                                                           'SmallImage': {'Height': {'Units': {'value': 'pixels'},
                                                                                     'value': '75'},
                                                                          'URL': {'value': 'http://ecx.images-amazon.com/images/I/41%2B1-PwEz4L._SL75_.jpg'},
                                                                          'Width': {'Units': {'value': 'pixels'},
                                                                                    'value': '75'}},
                                                           'Studio': {'value': 'Nintendo'},
                                                           'Title': {'value': 'Nintendo '
                                                                              'Pokemon '
                                                                              'Go '
                                                                              'Plus'},
                                                           'lang': {'value': 'en-US'}}},
                      'Identifiers': {'MarketplaceASIN': {'ASIN': {'value': 'B01H482N6E'},
                                                          'MarketplaceId': {'value': 'ATVPDKIKX0DER'}}},
                      'Relationships': {},
                      'SalesRankings': {'SalesRank': [{'ProductCategoryId': {'value': 'video_games_display_on_website'},
                                                       'Rank': {'value': '35'}},
                                                      {'ProductCategoryId': {'value': '14218821'},
                                                       'Rank': {'value': '1'}},
                                                      {'ProductCategoryId': {'value': '471304'},
                                                       'Rank': {'value': '22'}}]}}}}

我怎样才能找到Title"的值，或者从这本字典中找到Title"值的最佳方法是什么?

How can I find the value of 'Title' or what would be the best way to find the value 'Title' from this dictionary?

当我尝试实现在 Stackoverflow 上找到的类似递归解决方案时，我得到一个 None 值.

When I try to implement similar recursive solutions I found on Stackoverflow, I get a None value.

我试过了:

def recursive_lookup(k, d):
    if k in d:
        return d[k]
    for v in d.values():
        if isinstance(v, dict):
            return recursive_lookup(k, v)
    return None

print(recursive_lookup('Title', productData.parsed))

推荐答案

您的代码的问题在于您没有回溯到其他词典.在返回之前，您不会遍历所有项目.通过返回，您可以切断循环.

The problem with your code is that you are not backtracking to other dictionaries. You don't loop through all the items before you return. By returning you cut off your loop.

下面的代码循环遍历所有字典，直到找到密钥或检查所有字典但什么也没找到才返回.

The code below loops through all of the dicts and doesn't return until it has either found the key or it has checked all the dicts and found nothing.

def recursive_lookup(k, d):
    if k in d: return d[k]
    for v in d.values():
        if isinstance(v, dict):
            a = recursive_lookup(k, v)
            if a is not None: return a
    return None

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