如何在字典中按值访问键？

Question

I have a dict that looks like the following:

d = {"employee": ['PER', 'ORG']}

I have a list of tags ('PER', 'ORG',....) that is extracted from the specific entity list .

for t in entities_with_tag: # it includes words with a tag such as: [PER(['Bill']), ORG(['Microsoft']), 
    f = t.tag # this extract only tag like: {'PER, ORG'}
    s =str(f)
    q.add(s)

Now I want if {'PER, ORG'} in q , and it matched with d.values() , it should give me the keys of {'PER, ORG'} which is 'employee' . I try it this but does not work.

for x in q:
   if str(x) in str(d.values()):
       print(d.keys()) # this print all the keys of dict.

Answer 1

If I understand correctly you should loop he dictionary instead of the tag list. You can check if the dictionary tags are in the list using sets.

d = {"employee": ['PER', 'ORG'],
    "located": ["ORG", "LOC"]}
q = ["PER", "ORG", "DOG", "CAT"]
qset = set(q)
for key, value in d.items():
    if set(value).issubset(qset):
        print (key)

Output:

employee

Answer 2

You mean with... nothing?

for x in q:
   if str(x) in d.values():
       print(d.keys())

Answer 3

What you can do is to switch keys and values in the dict and then access by key.

tags = ('PER', 'ORG')
data = dict((val, key) for key, val in d.items())
print(data[tags])

Just be careful to convert the lists in tuples, since lists are not hashable.

Another solution would be to extract both key and value in a loop. But that's absolutely NOT efficient at all.

for x in q:
    if str(x) in str(d.values()):
        for key, val in d.items():
            if val == x:
                print(key) # this print all the keys of dict.

Answer 4

What you can do is make two lists. One which contains the keys and one which contains the values. Then for the index of the required value in the list with values you can call the key from the list of keys.

    d = {"employee": ['PER', 'ORG']}

    key_list = list(d.keys()) 
    val_list = list(d.values()) 

    print(key_list[val_list.index(['PER','ORG'])

Refer: https://www.geeksforgeeks.org/python-get-key-from-value-in-dictionary/