Python: Sort (ascending and descending) a dictionary by value

Last update on December 21 2024 07:28:08 (UTC/GMT +8 hours)

Write a Python program to sort (ascending and descending) a dictionary by value.

Sample Solution-1:

Python Code:

# Import the 'operator' module, which provides functions for common operations like sorting.
import operator

# Create a dictionary 'd' with key-value pairs.
d = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
	
# Print the original dictionary 'd'.
print('Original dictionary : ',d)

# Sort the items (key-value pairs) in the dictionary 'd' based on the values (1st element of each pair).
# The result is a list of sorted key-value pairs.
sorted_d = sorted(d.items(), key=operator.itemgetter(1))

# Print the dictionary 'sorted_d' in ascending order by value.
print('Dictionary in ascending order by value : ',sorted_d)

# Convert the sorted list of key-value pairs back into a dictionary.
# The 'reverse=True' argument sorts the list in descending order by value.
sorted_d = dict( sorted(d.items(), key=operator.itemgetter(1), reverse=True))

# Print the dictionary 'sorted_d' in descending order by value.
print('Dictionary in descending order by value : ',sorted_d)  

Sample Output:

Original dictionary :  {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
Dictionary in ascending order by value :  [(0, 0), (2, 1), (1, 2), (4, 3), (3, 4)]
Dictionary in descending order by value :  {3: 4, 4: 3, 1: 2, 2: 1, 0: 0}

Sample Solution-2:

Note: Dictionary values must be of the same type.

• Use dict.items() to get a list of tuple pairs from d and sort it using a lambda function and sorted().
• Use dict() to convert the sorted list back to a dictionary.
• Use the reverse parameter in sorted() to sort the dictionary in reverse order, based on the second argument.

Python Code:

# Define a function 'sort_dict_by_value' that takes a dictionary 'd' and an optional 'reverse' flag.
# It returns the dictionary sorted by values in ascending or descending order, based on the 'reverse' flag.
def sort_dict_by_value(d, reverse = False):
    return dict(sorted(d.items(), key = lambda x: x[1], reverse = reverse))

# Print a message indicating the start of the code section.
print("Original dictionary elements:")

# Create a dictionary 'colors' with key-value pairs.
colors = {'Red': 1, 'Green': 3, 'Black': 5, 'White': 2, 'Pink': 4}

# Print the original dictionary 'colors'.
print(colors)

# Print a message indicating the start of the sorting process in ascending order.
print("\nSort (ascending) the said dictionary elements by value:")

# Call the 'sort_dict_by_value' function to sort the 'colors' dictionary by value in ascending order.
# Print the result.
print(sort_dict_by_value(colors))

# Print a message indicating the start of the sorting process in descending order.
print("\nSort (descending) the said dictionary elements by value:")

# Call the 'sort_dict_by_value' function with 'reverse=True' to sort the 'colors' dictionary by value in descending order.
# Print the result.
print(sort_dict_by_value(colors, True)) 

Sample Output:

Original dictionary elements:
{'Red': 1, 'Green': 3, 'Black': 5, 'White': 2, 'Pink': 4}

Sort (ascending) the said dictionary elements by value:
{'Red': 1, 'White': 2, 'Green': 3, 'Pink': 4, 'Black': 5}

Sort (descending) the said dictionary elements by value:
{'Black': 5, 'Pink': 4, 'Green': 3, 'White': 2, 'Red': 1}

Flowchart:

Python Code Editor:

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