Python – Maximum value assignment in Nested Dictionary
Last Updated :
27 Apr, 2023
Sometimes, while working with Python dictionaries, we can have a problem in which we need to assign to the outer key, the item with maximum value in inner keys. This kind of problem can occur in day-day programming and web development domains. Let’s discuss a way in which this task can be performed.
Input : test_dict = {‘Manjeet’: {‘English’: 19, ‘Maths’: 1}, ‘Himani’: {‘English’: 18, ‘Maths’: 17}}
Output : [{‘Manjeet’: (‘English’, 19)}, {‘Himani’: (‘English’, 18)}]
Input : test_dict = {‘Manjeet’ : {‘Maths’:10}}
Output : [{‘Manjeet’: (‘Maths’, 10)}]
Method : Using Counter().most_common() + items() + loop The combination of above functions constitute the brute way to solve this problem. In this, we extract the maximum element using most_common() and items() is used to extract key-value pair.
Python3
from collections import Counter
test_dict = { 'Manjeet' : { 'Maths' : 1 , 'English' : 0 , 'Physics' : 2 , 'Chemistry' : 3 },
'Akash' : { 'Maths' : 0 , 'English' : 0 , 'Physics' : 3 , 'Chemistry' : 2 },
'Nikhil' : { 'Maths' : 4 , 'English' : 2 , 'Physics' : 2 , 'Chemistry' : 3 },
'Akshat' : { 'Maths' : 1 , 'English' : 0 , 'Physics' : 2 , 'Chemistry' : 0 }}
print ( "The original dictionary : " + str (test_dict))
res = []
for key, val in test_dict.items():
cnt = Counter(val)
res.append({key : cnt.most_common( 1 )[ 0 ]})
print ( "Maximum element key : " + str (res))
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Output
The original dictionary : {'Manjeet': {'Maths': 1, 'English': 0, 'Physics': 2, 'Chemistry': 3}, 'Akash': {'Maths': 0, 'English': 0, 'Physics': 3, 'Chemistry': 2}, 'Nikhil': {'Maths': 4, 'English': 2, 'Physics': 2, 'Chemistry': 3}, 'Akshat': {'Maths': 1, 'English': 0, 'Physics': 2, 'Chemistry': 0}}
Maximum element key : [{'Manjeet': ('Chemistry', 3)}, {'Akash': ('Physics', 3)}, {'Nikhil': ('Maths', 4)}, {'Akshat': ('Physics', 2)}]
Time Complexity: O(n*n), where n is the length of the list test_dict
Auxiliary Space: O(n) additional space of size n is created where n is the number of elements in the res list
Using the built-in max() function to find the maximum value in a nested dictionary:
Approach:
- Initialize an empty list to store the output.
- Iterate through the nested dictionary using loops.
- For each key in the outer dictionary, use the max() function to find the maximum value in the inner dictionary.
- Append a new dictionary to the output list with the key and value pair of the maximum value.
- Return the output list.
Python3
def max_value(test_dict):
output = []
for key in test_dict:
max_key, max_value = max (test_dict[key].items(), key = lambda x: x[ 1 ])
output.append({key: (max_key, max_value)})
return output
test_dict = { 'Manjeet' : { 'English' : 19 , 'Maths' : 1 }, 'Himani' : { 'English' : 18 , 'Maths' : 17 }}
print (max_value(test_dict))
test_dict = { 'Manjeet' : { 'Maths' : 10 }}
print (max_value(test_dict))
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Output
[{'Manjeet': ('English', 19)}, {'Himani': ('English', 18)}]
[{'Manjeet': ('Maths', 10)}]
Time Complexity: O(n^2) where n is the number of key-value pairs in the nested dictionary. This is because we are iterating through the nested dictionary using loops and using the max() function for each inner dictionary.
Space Complexity: O(n) where n is the number of key-value pairs in the nested dictionary. This is because we are storing the output in a list.
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