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[英]How to create a dictionary to reverse lookup list items that each have sets?
[英]Reverse lookup Dictionary
我有以下字典,我想進行反向查找。
countries_dict = {'Andorra': ('Europe', 'Andorra la Vella'),
'Afghanistan': ('Asia', 'Kabul'),
'Antigua and Barbuda': ('North America', "St. John's"),
'Albania': ('Europe', 'Tirana'),
'Armenia': ('Asia', 'Yerevan'),
'Angola': ('Africa', 'Luanda'),
'Argentina': ('South America', 'Buenos Aires'),
'Austria': ('Europe', 'Vienna'),
'Australia': ('Oceania', 'Canberra'),
'Azerbaijan': ('Asia', 'Baku'),
'Barbados': ('North America', 'Bridgetown'),
'Bangladesh': ('Asia', 'Dhaka'),
'Belgium': ('Europe', 'Brussels')}
我的代碼如下所示:
def create_continents_dict(dct = dict) -> dict:
reversed_dictionary = {value[0] : key for (key, value) in dct.items()}
return reversed_dictionary
print(create_continents_dict(countries_dict))
{'Europe': 'Belgium', 'Asia': 'Bangladesh', 'North America': 'Barbados', 'Africa': 'Angola', 'South America': 'Argentina', 'Oceania': 'Australia'}
但是,我只得到它作為價值查找的最后一個國家。 我想要的是作為國家列表的價值。 有了上面的代碼,我應該期待每個擁有相同大陸的國家/地區的代碼,它應該在列表中嗎?
{'Europe': ['Andorra', 'Albania', 'Austria', 'Belgium'] 'Asia': ['Afghanistan', 'Armenia', 'Azerbaijan', 'Bangladesh'], 'North America': ['Antigua and Barbuda', 'Barbados'], 'Africa': ['Angola'], 'South America': ['Argentina'], 'Oceania': ['Australia']}
您可以將dict.setdefault()
與默認列表 ( []
) 一起使用,然后在其中附加國家/地區:
out = {}
for country, (continent, _) in countries_dict.items():
out.setdefault(continent, []).append(country)
print(out)
印刷:
{'Europe': ['Andorra', 'Albania', 'Austria', 'Belgium'],
'Asia': ['Afghanistan', 'Armenia', 'Azerbaijan', 'Bangladesh'],
'North America': ['Antigua and Barbuda', 'Barbados'],
'Africa': ['Angola'],
'South America': ['Argentina'],
'Oceania': ['Australia']}
你可以在這里使用collections.defaultdict
def reverse_dict(countries_dict):
reversed_dictionary = defaultdict(list)
for key, value in countries_dict.items():
reversed_dictionary[value[0]].append(key)
return reversed_dictionary
>>> reverse_dict(countries_dict)
defaultdict(<class 'list'>,
{'Europe': ['Andorra', 'Albania', 'Austria', 'Belgium'],
'Asia': ['Afghanistan', 'Armenia', 'Azerbaijan', 'Bangladesh'],
'North America': ['Antigua and Barbuda', 'Barbados'],
'Africa': ['Angola'],
'South America': ['Argentina'],
'Oceania': ['Australia']})
嘗試
from collections import defaultdict
countries_dict = {'Andorra': ('Europe', 'Andorra la Vella'),
'Afghanistan': ('Asia', 'Kabul'),
'Antigua and Barbuda': ('North America', "St. John's"),
'Albania': ('Europe', 'Tirana'),
'Armenia': ('Asia', 'Yerevan'),
'Angola': ('Africa', 'Luanda'),
'Argentina': ('South America', 'Buenos Aires'),
'Austria': ('Europe', 'Vienna'),
'Australia': ('Oceania', 'Canberra'),
'Azerbaijan': ('Asia', 'Baku'),
'Barbados': ('North America', 'Bridgetown'),
'Bangladesh': ('Asia', 'Dhaka'),
'Belgium': ('Europe', 'Brussels')}
d = defaultdict(list)
for k,v in countries_dict.items():
d[v[0]].append(k)
print(d)
輸出
defaultdict(<class 'list'>, {'Europe': ['Andorra', 'Albania', 'Austria', 'Belgium'], 'Asia': ['Afghanistan', 'Armenia', 'Azerbaijan', 'Bangladesh'], 'North America': ['Antigua and Barbuda', 'Barbados'], 'Africa': ['Angola'], 'South America': ['Argentina'], 'Oceania': ['Australia']})
def create_continents_dict(dct = dict) -> dict:
reversed_dictionary = {}
for key, value in dct.items():
if value[0] not in reversed_dictionary.keys():
reversed_dictionary[value[0]] = []
reversed_dictionary[value[0]].append(key)
return reversed_dictionary
輸出:
print(create_continents_dict(countries_dict))
{'Europe': ['Andorra', 'Albania', 'Austria', 'Belgium'], 'Asia': ['Afghanistan', 'Armenia', 'Azerbaijan', 'Bangladesh'], 'North America': ['Antigua and Barbuda', 'Barbados'], 'Africa': ['Angola'], 'South America': ['Argentina'], 'Oceania': ['Australia']}
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