打印python中json文件的所有键

print All the keys of a json file in python

我有一个文件夹，其中有大约20000个JSON文件。我想找出每个JSON的所有唯一键，并对所有键进行联合。但是，我只是被困在了最初的一步。我可以找到单个JSON文件的密钥。

到目前为止，我已经编写了以下代码：

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from pprint import pprint
import json
json_data=open("/Users/akira/out/1.json")
jdata = json.load(json_data)

for key, value in jdata:
pprint("Key:")
pprint(key)

它给我一个错误如下：

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Traceback (most recent call last):
File"/Users/akira/PycharmProjects/csci572/linkedbased.py", line 8, in <module>
for key, value in jdata:
ValueError: need more than 1 value to unpack

我的JSON是一个嵌套的JSON。请告诉我怎样才能拿到所有的钥匙。

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{
"a":"Offer",
"inLanguage":"et",
"availabl": {
"a":"Place",
"address": {
"a":"PostalAddress",
"name":"Oklahoma"
}
},
"description":"Smith and Wesson 686 357 magnum 6 inch barrel wood handle great condition shoots great.",
"priceCurrency":"USD",
"geonames_address": [
{
"a":"PopulatedPlace",
"hasIdentifier": {
"a":"Identifier",
"label":"4552707",
"hasType":"http://dig.isi.edu/gazetteer/data/SKOS/IdentifierTypes/GeonamesId"
},
"hasPreferredName": {
"a":"Name",
"label":"Tahlequah"
},
"uri":"http://dig.isi.edu/gazetteer/data/geonames/place/4552707",
"fallsWithinState1stDiv": {
"a":"State1stDiv",
"uri":"http://dig.isi.edu/gazetteer/data/geonames/place/State1stDiv/US_OK",
"hasName": {
"a":"Name",
"label":"Oklahoma"
}
},
"score": 0.5,
"fallsWithinCountry": {
"a":"Country",
"uri":"http://dig.isi.edu/gazetteer/data/geonames/place/Country/US",
"hasName": {
"a":"Name",
"label":"United States"
}
},
"fallsWithinCountyProvince2ndDiv": {
"a":"CountyProvince2ndDiv",
"uri":"http://dig.isi.edu/gazetteer/data/geonames/place/CountyProvince2ndDiv/US_OK_021"
},
"geo": {
"lat": 35.91537,
"lon": -94.96996
}
}
],
"price": 750,
"title":"For Sale: Smith & Wesson 686",
"publisher": {
"a":"Organization",
"name":"armslist.com",
"uri":"http://dig.isi.edu/weapons/data/organization/armslist"
},
"uri":"http://dig.isi.edu/weapons/data/page/13AD9516F01012C5F89E8AADAE5D7E1E2BA97FF9/1433463841000/processed",
"seller": {
"a":"PersonOrOrganization",
"description":"Private Party"
} //, ...
}

用for key, value in jdata.items():代替for key, value in jdata:，如下：

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for key, value in data.items():
pprint("Key:")
pprint(key)

查看dict文档：

items():

Return a new view of the dictionary’s items ((key, value) pairs).

编辑：如果要获取所有嵌套键，而不仅仅是顶级键，可以采用类似于另一个答案中建议的方法，例如：

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def get_keys(dl, keys_list):
if isinstance(dl, dict):
keys_list += dl.keys()
map(lambda x: get_keys(x, keys_list), dl.values())
elif isinstance(dl, list):
map(lambda x: get_keys(x, keys_list), dl)

keys = []
get_keys(jdata, keys)

print(keys)
# [u'a', u'inLanguage', u'description', u'priceCurrency', u'geonames_address', u'price', u'title', u'availabl', u'uri', u'seller', u'publisher', u'a', u'hasIdentifier', u'hasPreferredName', u'uri', u'fallsWithinState1stDiv', u'score', u'fallsWithinCountry', u'fallsWithinCountyProvince2ndDiv', u'geo', u'a', u'hasType', u'label', u'a', u'label', u'a', u'uri', u'hasName', u'a', u'label', u'a', u'uri', u'hasName', u'a', u'label', u'a', u'uri', u'lat', u'lon', u'a', u'address', u'a', u'name', u'a', u'description', u'a', u'name', usury']

print(list(set(keys))) # unique list of keys
# [u'inLanguage', u'fallsWithinState1stDiv', u'label', u'hasName', u'title', u'hasPreferredName', u'lon', u'seller', u'score', u'description', u'price', u'address', u'lat', u'fallsWithinCountyProvince2ndDiv', u'geo', u'a', u'publisher', u'hasIdentifier', u'name', u'priceCurrency', u'geonames_address', u'hasType', u'availabl', u'uri', u'fallsWithinCountry']

你应该在for key, value in jdata中使用dict.items()或dict.iteritems()。

所以，应该是

1	for key, value in jdata.items():

或

1	for key, value in jdata.iteritems():

分别用于python3和python2。

请参阅此问题的答案以了解两者的区别：dict.items()和dict.iteritems()之间的区别是什么？

如果只需要迭代字典的键，甚至可以尝试dict.keys()或dict.iterkeys()。