Python: Generate the combinations of n distinct objects taken from a list

Last update on December 21 2024 13:10:04 (UTC/GMT +8 hours)

Generate Combinations from List

Write a Python program to generate combinations of n distinct objects taken from the elements of a given list.

Visual Presentation:

Sample Solution:

Python Code:

# Define a function 'combination' that generates combinations of 'n' distinct objects from 'n_list'
def combination(n, n_list):
    # Base case: If 'n' is less than or equal to 0, yield an empty list and return
    if n <= 0:
        yield []
        return
    
    # Iterate through the elements in 'n_list'
    for i in range(len(n_list)):
        # Take one element 'c_num' at a time starting from index 'i'
        c_num = n_list[i:i+1]
        
        # Recursively generate combinations of 'n-1' distinct objects from the remaining elements
        for a_num in combination(n-1, n_list[i+1:]):
            # Yield the current element 'c_num' combined with the combinations of 'n-1' elements 'a_num'
            yield c_num + a_num

# Create a list 'n_list' containing integers
n_list = [1, 2, 3, 4, 5, 6, 7, 8, 9]

# Print a message indicating the original list
print("Original list:")
# Print the original list
print(n_list)

# Assign an integer 'n' with the value 2
n = 2

# Call the 'combination' function with 'n' and 'n_list' and store the generator in the 'result' variable
result = combination(n, n_list)

# Print a message indicating the combinations of 'n' distinct objects
print("\nCombinations of", n, "distinct objects:")

# Iterate through the generator and print each combination
for e in result:
    print(e)

Sample Output:

Original list:
[1, 2, 3, 4, 5, 6, 7, 8, 9]

Combinations of 2 distinct objects:
[1, 2]
[1, 3]
[1, 4]
[1, 5]
[1, 6]
[1, 7]
[1, 8]
[1, 9]
[2, 3]
[2, 4]
[2, 5]
[2, 6]
[2, 7]
[2, 8]
[2, 9]
[3, 4]
[3, 5]
[3, 6]
[3, 7]
[3, 8]
[3, 9]
[4, 5]
[4, 6]
[4, 7]
[4, 8]
[4, 9]
[5, 6]
[5, 7]
[5, 8]
[5, 9]
[6, 7]
[6, 8]
[6, 9]
[7, 8]
[7, 9]
[8, 9]

Flowchart:

Python Code Editor:

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