Python - Extract Key's Value, if Key Present in List and Dictionary - GeeksforGeeks

30 Aug, 2020
Given a list, dictionary and a Key K, print value of K from dictionary if key present in both, list and dictionary.
Input : test_list = [“Gfg”, “is”, “Good”, “for”, “Geeks”], test_dict = {“Gfg” : 5, “Best” : 6}, K = “Gfg”Output : 5Explanation : “Gfg” is present in list and has value 5 in dictionary.
Input : test_list = [“Good”, “for”, “Geeks”], test_dict = {“Gfg” : 5, “Best” : 6}, K = “Gfg”Output : NoneExplanation : “Gfg” not present in List.
Method #1 : Using all() + generator expression
 The combination of above functions offer one of the ways in which this problem can be solved. In this we use all() to check for occurrence in both dictionary and list. If result is true value is extracted to result.
Python3
# Python3 code to demonstrate working of # Extract Key's Value, if Key Present in List and Dictionary# Using all() + list comprehension  # initializing listtest_list = ["Gfg", "is", "Good", "for", "Geeks"]  # initializing Dictionarytest_dict = {"Gfg" : 2, "is" : 4, "Best" : 6}  # initializing K K = "Gfg"  # printing original list and Dictionaryprint("The original list : " + str(test_list))print("The original Dictionary : " + str(test_dict))  # using all() to check for occurrence in list and dict# encapsulating list and dictionary keys in list res = None if all(K in sub for sub in [test_dict, test_list]):    res = test_dict[K]  # printing result print("Extracted Value : " + str(res))
The original list : ['Gfg', 'is', 'Good', 'for', 'Geeks']
The original Dictionary : {'Gfg': 2, 'is': 4, 'Best': 6}
Extracted Value : 2

Method #2 : Using set() + intersection()
This is one another way to check for key’s presence in both the containers. In this, we compute intersection of all values of list and dict keys, and test for Key’s occurrence in that.
Python3
# Python3 code to demonstrate working of # Extract Key's Value, if Key Present in List and Dictionary# Using set() + intersection()  # initializing listtest_list = ["Gfg", "is", "Good", "for", "Geeks"]  # initializing Dictionarytest_dict = {"Gfg" : 2, "is" : 4, "Best" : 6}  # initializing K K = "Gfg"  # printing original list and Dictionaryprint("The original list : " + str(test_list))print("The original Dictionary : " + str(test_dict))  # conversion of lists to set and intersection with keys # using intersectionres = None if K in set(test_list).intersection(test_dict):    res = test_dict[K]  # printing result print("Extracted Value : " + str(res))
The original list : ['Gfg', 'is', 'Good', 'for', 'Geeks']
The original Dictionary : {'Gfg': 2, 'is': 4, 'Best': 6}
Extracted Value : 2

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