Python program to Sort a List of Dictionaries by the Sum of their Values

When working with lists of dictionaries, you may need to sort them based on the sum of their values. Python provides multiple approaches to achieve this using the sort() method with custom key functions.

Method 1: Using a Custom Function

Define a function to calculate the sum of dictionary values and use it as the sorting key ?

def sum_value(row):
    return sum(list(row.values()))

my_dict = [{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]

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

my_dict.sort(key=sum_value)

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

The dictionary is:
[{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]
The result is:
[{48: 29, 17: 53}, {21: 13, 44: 35, 34: 56}, {1: 155}, {11: 75, 70: 19, 39: 70}]

Method 2: Using Lambda Function

A more concise approach uses a lambda function directly in the sort method ?

my_dict = [{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]

print("Original list:")
print(my_dict)

my_dict.sort(key=lambda x: sum(x.values()))

print("Sorted by sum of values:")
print(my_dict)

Original list:
[{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]
Sorted by sum of values:
[{48: 29, 17: 53}, {21: 13, 44: 35, 34: 56}, {1: 155}, {11: 75, 70: 19, 39: 70}]

Method 3: Using sorted() for Immutable Sorting

Use sorted() to create a new sorted list without modifying the original ?

my_dict = [{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]

print("Original list:")
print(my_dict)

sorted_dict = sorted(my_dict, key=lambda x: sum(x.values()))

print("Sorted list:")
print(sorted_dict)

print("Original list (unchanged):")
print(my_dict)

Original list:
[{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]
Sorted list:
[{48: 29, 17: 53}, {21: 13, 44: 35, 34: 56}, {1: 155}, {11: 75, 70: 19, 39: 70}]
Original list (unchanged):
[{21: 13, 44: 35, 34: 56}, {11: 75, 70: 19, 39: 70}, {1: 155}, {48: 29, 17: 53}]

Comparison

Conclusion

Use lambda functions for simple sorting operations and custom functions for complex logic. Choose sorted() when you need to preserve the original list structure.