Python | Check if given multiple keys exist in a dictionary

A dictionary in Python consists of a collection of key-value pairs. Each key-value pair maps the key to its associated value.

Input : dict[] = {“neveropen” : 1, “practice” : 2, “contribute” :3} keys[] = {“neveropen”, “practice”} Output : Yes Input : dict[] = {“neveropen” : 1, “practice” : 2, “contribute” :3} keys[] = {“neveropen”, “ide”} Output : No

Let’s discuss various ways of checking multiple keys in a dictionary : 

Method #1 Using comparison operator : This is the common method where we make a set which contains keys that use to compare and using comparison operator we check if that key present in our dictionary or not. 

True
False

Time complexity: O(k), where k is the number of keys in the dictionary
Auxiliary space: O(k), to create the set of keys for comparison.

Method #2 Using issubset() : In this method, we will check the keys that we have to compare is subset() of keys in our dictionary or not. 

True
False

Time complexity: O(n), where n is the length of the test_keys list.
Auxiliary space: O(n), as we are creating a dictionary with n key-value pairs.

Method #3 Using if and all statement : In this method we will check that if all the key elements that we want to compare are present in our dictionary or not . 

keys are present
keys are not present

Time complexity: O(n), where n is the number of key-value pairs in the dictionary.
Auxiliary space: O(n), to store the keys and values in dictionary.

Method #4 : Alternatively, you can use a list comprehension and list comparison to achieve a similar result:

True
False

Time complexity: O(n),
Auxiliary Space: O(n) and, since it involves a single pass through the list of keys to check. It uses a list comprehension to generate a list of keys that are present in the dictionary.