Keys with Maximum value - Python
Last Updated : 24 Feb, 2025
In Python, dictionaries are used to store data in key-value pairs and our task is to find the key or keys that have the highest value in a dictionary. For example, in a dictionary that stores the scores of students, you might want to know which student has the highest score. Different methods to identify the key or keys associated with the maximum value are:
Using max() + list comprehension + values()
This approach is a simple and most efficient way to find the key or keys with the highest value in a dictionary. First, we use the max() function to find the highest value in the dictionary. Then, with list comprehension, we can loop through the dictionary and collect all the keys that have this maximum value. The values() method helps to easily get all the values from the dictionary, which we use to find the maximum.
Python d = {'Gfg' : 2, 'for' : 1, 'CS' : 2} temp = max(d.values()) res = [key for key in d if d[key] == temp] print(res) Explanation:
- max(d.values()) finds the maximum value in the dictionary.
- List comprehension iterates through the keys and adds those with the maximum value to the list res.
- The list res is printed, showing the keys with the maximum value.
Using all() + list comprehension
In this approach, we use list comprehension to loop through the dictionary and check if the value of each key is equal to the maximum value. The all() function is used to verify if all the conditions are met for each key-value pair.
Python d = {'Gfg' : 2, 'for' : 1, 'CS' : 2} res = [key for key in d if all(d[temp] <= d[key] for temp in d)] print(res) Explanation:
- list comprehension iterates through all keys in the dictionary d.
- For each key, it checks if its value is greater than or equal to all other values in the dictionary using all().
- keys that satisfy this condition are added to the list res.
Using for loop
In this approach, we manually loop through the dictionary and check the value of each key. If the value matches the maximum value, we add the key to a list.
Python d = {'CS': 2, 'Gfg': 2, 'for': 1} max_val = max(d.values()) max_keys = [] for key in d: if d[key] == max_val: max_keys.append(key) print(max_keys) Explanation:
- max(d.values()) finds the maximum value in the dictionary d.
- A for loop iterates through all the keys in the dictionary.
- For each key, it checks if its value equals the maximum value and if so, adds the key to the list max_keys.
Using filter() and lambda()
In this approach, we use the filter() function combined with a lambda() function to filter out the keys that have the maximum value. The filter() function checks each key-value pair, and the lambda() function defines the condition (whether the value is equal to the maximum value).
Python d = {'Gfg': 2, 'for': 1, 'CS': 2} max_val = max(d.values()) res = list(filter(lambda x: d[x] == max_val, d)) print(res) Explanation:
- max(d.values()) finds the maximum value in the dictionary d.
- filter() with a lambda function iterates through the dictionary and checks if the value of each key equals the maximum value.
- keys that meet this condition are collected into a list using list().
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