Python program to print design door mat texture using characters

A door mat pattern is a decorative text design that creates a symmetric mat-like structure. In this pattern, we use hyphens (-), dots (.), and pipe symbols (|) to create a design with "WELCOME" in the center. The mat has dimensions n × m, where m is a multiple of n.

Understanding the Pattern

The door mat follows this structure:

• Top half: Expanding pattern from 1 to n-1 (odd numbers only)
• Middle: "WELCOME" text surrounded by hyphens
• Bottom half: Mirror of the top half in reverse order

Each row contains:

• Left padding of hyphens
• Pattern units of ".|." repeated
• Right padding of hyphens

Example with Small Dimensions

Let's start with a simple example where n = 5 and m = 15:

def create_door_mat(n, m):
    # Top half - expanding pattern
    for i in range(1, n, 2):
        pattern = '.|.' * i
        padding = '-' * ((m - len(pattern)) // 2)
        print(padding + pattern + padding)
    
    # Middle - WELCOME text
    welcome_padding = '-' * ((m - 7) // 2)
    print(welcome_padding + 'WELCOME' + welcome_padding)
    
    # Bottom half - contracting pattern (mirror of top)
    for i in range(n-2, -1, -2):
        pattern = '.|.' * i
        padding = '-' * ((m - len(pattern)) // 2)
        print(padding + pattern + padding)

# Example with small dimensions
n = 5
m = 15
create_door_mat(n, m)

------.|.------
---.|..|..|.---
----WELCOME----
---.|..|..|.---
------.|.------

Complete Implementation

Here's the complete solution with a larger example:

def create_door_mat(n, m):
    # Top half - expanding pattern
    for i in range(1, n, 2):
        pattern = '.|.' * i
        padding = '-' * ((m - len(pattern)) // 2)
        print(padding + pattern + padding)
    
    # Middle - WELCOME text
    welcome_padding = '-' * ((m - 7) // 2)
    print(welcome_padding + 'WELCOME' + welcome_padding)
    
    # Bottom half - contracting pattern (mirror of top)
    for i in range(n-2, -1, -2):
        pattern = '.|.' * i
        padding = '-' * ((m - len(pattern)) // 2)
        print(padding + pattern + padding)

# Test with larger dimensions
n = 7
m = 21
print(f"Door mat pattern ({n} x {m}):")
create_door_mat(n, m)

Door mat pattern (7 x 21):
----------.|.----------
-------.|..|..|.-------
----.|..|..|..|..|.----
-------WELCOME-------
----.|..|..|..|..|.----
-------.|..|..|.-------
----------.|.----------

How It Works

The algorithm works in three phases:

1. Top Half: Loop from 1 to n-1 with step 2, creating expanding rows
2. Middle: Print "WELCOME" with appropriate padding
3. Bottom Half: Loop from n-2 to 0 with step -2, creating contracting rows

For each row, the padding calculation ensures the pattern stays centered:

• Pattern length = i × 3 (each ".|." is 3 characters)
• Padding on each side = (m - pattern_length) ÷ 2

Conclusion

The door mat pattern uses symmetric loops and string repetition to create a decorative text design. The key is calculating proper padding to center each row and using odd numbers to create the expanding/contracting effect.