如何从 Python 字典中的值中获取键？
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How to get the key from value in a dictionary in Python?
提问by Peter
d[key] = value
but how to get the keys from value?
但是如何从值中获取键呢？
For example:
例如：
a = {"horse": 4, "hot": 10, "hangover": 1, "hugs": 10}
b = 10
print(do_something with 10 to get ["hot", "hugs"])
回答by John Kugelman
You can write a list comprehension to pull out the matching keys.
您可以编写一个列表推导式来提取匹配的键。
print([k for k,v in a.items() if v == b])
回答by Mohamed Ali JAMAOUI
Something like this can do it:
像这样的事情可以做到：
for key, value in a.iteritems():
if value == 10:
print key
If you want to save the associated keys to a value in a list, you edit the above example as follows:
如果要将关联的键保存到列表中的值，请按如下方式编辑上面的示例：
keys = []
for key, value in a.iteritems():
if value == 10:
print key
keys.append(key)
You can also do that in a list comprehension as pointed out in an other answer.
您也可以在其他答案中指出的列表理解中做到这一点。
b = 10
keys = [key for key, value in a.iteritems() if value == b]
Note that in python 3, dict.itemsis equivalent to dict.iteritemsin python 2, check this for more details: What is the difference between dict.items() and dict.iteritems()?
请注意，在 python 3 中，dict.items相当于dict.iteritems在 python 2 中，查看更多详细信息：dict.items() 和 dict.iteritems() 之间有什么区别？
