Python – Display the key of list value with maximum range

When it is required to display the key of list value with maximum range, a simple iteration is used. The range of a list is the difference between its maximum and minimum values.

Example

Below is a demonstration of the same −

my_dict = {"pyt" : [26, 12, 34, 21], "fun" : [41, 27, 43, 53, 18], "learning" : [21, 30, 29, 13]}

print("The dictionary is :")
print(my_dict)

max_range = 0
result_key = ""

for key, values in my_dict.items():
    current_range = max(values) - min(values)
    if current_range > max_range:
        max_range = current_range
        result_key = key

print("The result is :")
print(result_key)
print(f"Maximum range: {max_range}")

Output

The dictionary is :
{'pyt': [26, 12, 34, 21], 'fun': [41, 27, 43, 53, 18], 'learning': [21, 30, 29, 13]}
The result is :
fun
Maximum range: 35

How It Works

The algorithm iterates through each key-value pair in the dictionary:

• pyt: Range = max([26, 12, 34, 21]) - min([26, 12, 34, 21]) = 34 - 12 = 22

• fun: Range = max([41, 27, 43, 53, 18]) - min([41, 27, 43, 53, 18]) = 53 - 18 = 35

• learning: Range = max([21, 30, 29, 13]) - min([21, 30, 29, 13]) = 30 - 13 = 17

The key "fun" has the maximum range of 35, so it is returned as the result.

Alternative Approach Using max() Function

You can also solve this using Python's built-in max() function with a key parameter ?

my_dict = {"pyt" : [26, 12, 34, 21], "fun" : [41, 27, 43, 53, 18], "learning" : [21, 30, 29, 13]}

result_key = max(my_dict, key=lambda k: max(my_dict[k]) - min(my_dict[k]))
max_range = max(my_dict[result_key]) - min(my_dict[result_key])

print(f"Key with maximum range: {result_key}")
print(f"Maximum range: {max_range}")

Key with maximum range: fun
Maximum range: 35

Conclusion

To find the key with maximum range, calculate the difference between max and min values for each list. The iterative approach is clear and easy to understand, while using max() with a lambda function provides a more concise solution.