Python: Grouping a sequence of key-value pairs into a dictionary of lists using collections module

Python Collections: Exercise-28 with Solution

Write a Python program to create a dictionary grouping a sequence of key-value pairs into a dictionary of lists. Use the collections module.

Sample Solution:

Python Code:

# Import the defaultdict class from the collections module
from collections import defaultdict

# Define a function 'grouping_dictionary' that groups a sequence of key-value pairs into a dictionary of lists
def grouping_dictionary(l):
    # Create a defaultdict 'd' to store lists of values associated with each key
    d = defaultdict(list)
    
    # Loop through the key-value pairs in the input list 'l'
    for k, v in l:
        # Append the value 'v' to the list associated with key 'k' in 'd'
        d[k].append(v)
    
    # Return the resulting dictionary
    return d

# Create a list of key-value pairs 'colors'
colors = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]

# Print a message to indicate the display of the original list
print("Original list:")

# Print the content of 'colors'
print(colors)

# Print a message to indicate the display after grouping the key-value pairs into a dictionary of lists
print("\nGrouping a sequence of key-value pairs into a dictionary of lists:")

# Call the 'grouping_dictionary' function with 'colors' and print the result
print(grouping_dictionary(colors)) 

Sample Output:

Original list:
[('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]

Grouping a sequence of key-value pairs into a dictionary of lists:
defaultdict(<class 'list'>, {'yellow': [1, 3], 'blue': [2, 4], 'red': [1]})

Flowchart:

Python Code Editor:

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