Python: Print a given N by M matrix of numbers line by line in forward > backwards > forward >... order

Last update on April 17 2025 13:05:32 (UTC/GMT +8 hours)

Matrix Forward-Backward Printing

Write a Python program to print a given N by M matrix of numbers line by line in forward > backwards > forward >... order.

Input matrix:
[[1, 2, 3, 4],
[5, 6, 7, 8],
[0, 6, 2, 8],
[2, 3, 0, 2]]
Output:
1
2
3
4
8
7
6
5
0
6
2
8
2
0
3
2

Sample Solution:

Python Code:

# Define a function to print a matrix in a zigzag pattern
def print_matrix(nums):
    # Initialize a flag to determine the printing direction
    flag = True 
    
    # Iterate through each line in the matrix
    for line in nums:
        # Check the flag to determine the printing direction
        if flag == True: 
            # If flag is True, print the elements from left to right
            i = 0
            while i < len(line):
                print(line[i])
                i += 1
            # Update the flag for the next line
            flag = False
        else: 
            # If flag is False, print the elements from right to left
            i = -1
            while i > -1 * len(line) - 1:
                print(line[i])
                i = i - 1
            # Update the flag for the next line
            flag = True

# Test the function with a matrix and print the elements in a zigzag pattern
print_matrix([[1, 2, 3, 4],
              [5, 6, 7, 8],
              [0, 6, 2, 8],
              [2, 3, 0, 2]])

Sample Output:

Explanation:

Here is a breakdown of the above Python code:

The function "print_matrix()" prints the elements of a matrix in a zigzag pattern.
It initializes a flag ('flag') to determine the printing direction.
It iterates through each line in the matrix ('nums').
Depending on the flag, it either prints the elements from left to right or from right to left.
After printing a line, it updates the flag for the next line.
The function is tested with a sample matrix, and the elements are printed in a zigzag pattern.

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to print each row of a matrix in alternating forward and reverse order.
Write a Python program to traverse a 2D array and print rows in zigzag order using slicing techniques.
Write a Python program to output a matrix with rows printed alternately from left-to-right and right-to-left.
Write a Python program to iterate over a matrix and display its rows in alternating directions without modifying the original array.

Go to:

Previous: Write a Python program to find the maximum profit in one transaction.
Next: Write a Python program to compute the largest product of three integers from a given list of integers.

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.