如何遍历字典并在Python中返回键? [英] How do I iterate over a dictionary and return the key in Python?

问题描述

我在Python中有一本字典，其中以人们的姓氏为键，每个键都有多个与之链接的值.有没有一种方法可以使用for循环遍历字典以搜索特定值，然后返回该值链接到的键?

I have a dictionary in Python with people's last names as the key and each key has multiple values linked to it. Is there a way to iterate over the dictionary using a for loop to search for a specific value and then return the key that the value is linked to?

for i in people:
      if people[i] == criteria: #people is the dictionary and criteria is just a string
            print dictKey #dictKey is just whatever the key is that the criteria matched element is linked to

也许还有多个匹配项，所以我需要人们输出多个键.

There maybe multiple matches as well so I need to people to output multiple keys.

推荐答案

您可以使用列表理解

print [key
          for people in peoples
          for key, value in people.items()
          if value == criteria]

这将打印出所有值与条件匹配的键.如果people是词典，则

This will print out all the keys for which the value matches the criteria. If people is the dictionary,

print [key
          for key, value in people.items()
          if value == criteria]

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