Finding a key by value in a Python dictionary
A dictionary is a collection of elements in key-value pairs. The elements stored in a dictionary are unordered. In this article, we will look at different ways to find a key by value in a Python dictionary. Normally, you use keys to access values, but here we will use values to access keys. A key here is an identifier associated with a value.
dict.items()Finding a key by value in a Python dictionary
using
dict.items()The method returns a list whose single element is a tuple consisting of the key of the dictionary value. We can get the key by iterating over dict.items()the results of and valuecomparing with the second element of the tuple.
Sample code:
my_dict = {"John": 1, "Michael": 2, "Shawn": 3}
def get_key(val):
for key, value in my_dict.items():
if val == value:
return key
return "There is no such Key"
print(get_key(1))
print(get_key(2))
Output:
John
Michael
Finding a key by value in a Python dictionary
using .keys()and.values()
dict.keys()Returns a list consisting of the keys of the dictionary; dict.values()returns a list consisting of the values of the dictionary. The order of the items produced in .keys()and is the same..values()
The Python list index()method gives the index of a given argument. We can valuepass to the generated key list's index()method to get the index of that value. We can then access the generated value list using the returned index to get the key.
my_dict = {"John": 1, "Michael": 2, "Shawn": 3}
list_of_key = list(my_dict.keys())
list_of_value = list(my_dict.values())
position = list_of_value.index(1)
print(list_of_key[position])
position = list_of_value.index(2)
print(list_of_key[position])
Output:
John
Michael
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