Generating patterns using nested for loops in Python

Creating a simple string using for loop

for i in range(10):
  print('*',end='')

Output

**********

Pattern #1 : Rectangle

for i in range(5):  # Outer loop for rows, change range stop value for more or fewer rows
  for j in range(10):  # Inner loop for columns, change range stop value for more or fewer columns
    print('*', end='')  # Print asterisk without moving to the next line
  print('')  # Move to the next line after printing all columns in a row

Output

**********
**********
**********
**********
**********

Pattern #2 : Right-Angled Triangle

for i in range(1, 10):  # Outer loop to control the number of rows
  for j in range(i):  # Inner loop to print stars or numbers in each row
    print('*', end='')  # Print asterisk without moving to the next line
    #print(j, end='')  # Uncomment to show numbers instead of asterisks  	
  print('')  # Move to the next line after each row

*
**
***
****
*****
******
*******
********
*********

Pattern #3 : Inverted Right-Angled Triangle

for i in range(10):  # Outer loop controls the number of rows
  for j in range(10 - i):  # Inner loop controls the decreasing number of columns
    print('*', end='')  # Print asterisk without moving to the next line
    #print(j, end='')  # Uncomment to display numbers instead of asterisks
  print('')  # Move to the next line after printing all columns in the row

**********
*********
********
*******
******
*****
****
***
**
*

Pattern #4 : Equilateral Triangle

for i in range(1, 11):  # Outer loop controls the number of rows
  for k in range(i, 10):  # Loop for spaces before the stars
    print(' ', end='')  # Print spaces to center the pyramid
  for j in range(2*i - 1):  # Loop for stars in the row
    print('*', end='')  # Print asterisk without moving to the next line
  print('')  # Move to the next line after printing all characters in the row

         *
        ***
       *****
      *******
     *********
    ***********
   *************
  ***************
 *****************
*******************

Pattern #5 : Inverted Triangle

for i in range(11, 0, -1):  # Outer loop for the number of rows, decreasing from 11 to 1
  for k in range(i, 11):  # Loop for spaces before the stars
    print(' ', end='')  # Print spaces to shift the stars
  for j in range((2*i) - 1):  # Loop for stars in the row
    print('*', end='')  # Print asterisk without moving to the next line
  print('')  # Move to the next line after printing all characters in the row

*********************
 *******************
  *****************
   ***************
    *************
     ***********
      *********
       *******
        *****
         ***
          *

Pattern #6 : Double-Sided Diamond Border

for i in range(0, 12):  # Outer loop controls the rows
  for k in range(i, 11):  # Loop for left-side stars
    print('*', end='')  # Print stars on the left
  for j in range((2*i)):  # Loop for spaces between stars
    print(' ', end='')  # Print spaces in the center
  for k in range(i, 11):  # Loop for right-side stars
    print('*', end='')  # Print stars on the right
  print('')  # Move to the next row after printing all characters

**********************
**********  **********
*********    *********
********      ********
*******        *******
******          ******
*****            *****
****              ****
***                ***
**                  **
*                    *

Pattern #7 :Diamond Pattern

n = 5  # Total number of rows for the top half of the diamond

for i in range(n):  # Loop for the upper part of the diamond
    print(" " * (n - i - 1) + "*" * (2 * i + 1))  
    # Print spaces followed by stars to form the upper half

for i in range(n - 2, -1, -1):  # Loop for the lower part of the diamond
    print(" " * (n - i - 1) + "*" * (2 * i + 1))  
    # Print spaces followed by stars to form the lower half

    *
   ***
  *****
 *******        
*********       
 *******        
  *****
   ***
    *

Pattern #8 : Hollow Square Pattern

n = 5  # Size of the square pattern

for i in range(n):  # Outer loop for rows
    for j in range(n):  # Inner loop for columns
        if i == 0 or i == n - 1 or j == 0 or j == n - 1:  
            print('*', end='')  # Print stars for the border of the square
        else:
            print(' ', end='')  # Print spaces for the hollow part
    print('')  # Move to the next row

*****
*   *
*   *
*   *
*****

Pattern #9 : Right Arrow Pattern

n = 5  # Number of rows for the arrow pattern

for i in range(n):  # Loop for the upward arrow
    print(' ' * i + '*')  # Print spaces followed by a single star

for i in range(n - 2, -1, -1):  # Loop for the downward arrow
    print(' ' * i + '*')  # Print spaces followed by a single star

*
 *
  *
   *
    *
   *
  *
 *
*

Pattern #10 : Diamond Outline Pattern

n = 5  # Number of rows for the diamond pattern

for i in range(n):  # Upper part of the diamond
    print(' ' * (n - i - 1) + '*' + ' ' * (2 * i - 1) + ('*' if i > 0 else ''))  
    # Print leading spaces, a star, middle spaces, and another star if not the first row

for i in range(n - 2, -1, -1):  # Lower part of the diamond
    print(' ' * (n - i - 1) + '*' + ' ' * (2 * i - 1) + ('*' if i > 0 else ''))  
    # Similar logic for the lower part, reversing the rows

    *
   * *
  *   *
 *     *
*       *
 *     *
  *   *
   * *
    *

Pattern #11 : Hourglass Pattern

n = 5  # Number of rows for the hourglass pattern

for i in range(n, 0, -1):  # Upper inverted triangle
    print(' ' * (n - i) + '*' * (2 * i - 1))  
    # Print leading spaces and stars for each row

for i in range(2, n + 1):  # Lower upright triangle
    print(' ' * (n - i) + '*' * (2 * i - 1))  
    # Print leading spaces and stars for each row

*********
 *******
  ***** 
   ***  
    *   
   ***
  *****
 *******
*********

Pattern #12 : Floyd's Triangle

n = 5  # Number of rows for the Floyd's Triangle
num = 1  # Starting number

for i in range(1, n + 1):  # Loop for each row
    for j in range(1, i + 1):  # Loop for each column in the row
        print(num, end=' ')  # Print the current number with a space
        num += 1  # Increment the number
    print('')  # Move to the next line after printing a row

1 
2 3 
4 5 6
7 8 9 10
11 12 13 14 15

Pattern #13 : Butterfly Pattern

n = 5  # Number of rows for the hourglass pattern

for i in range(1, n + 1):  # Upper part of the hourglass
    print('*' * i + ' ' * (2 * (n - i)) + '*' * i)  
    # Print stars, spaces, and then stars again

for i in range(n, 0, -1):  # Lower part of the hourglass
    print('*' * i + ' ' * (2 * (n - i)) + '*' * i)  
    # Similar logic as the upper part but in reverse

*        *
**      **
***    ***
****  ****
**********
**********
****  ****
***    ***
**      **
*        *

Pattern #14 Pascal's Triangle

n = 5  # Number of rows for Pascal's Triangle

for i in range(n):  # Loop through each row
    num = 1  # Initialize the first number in the row
    print(' ' * (n - i), end='')  # Print leading spaces for alignment
    for j in range(i + 1):  # Loop through each position in the row
        print(num, end=' ')  # Print the current number
        num = num * (i - j) // (j + 1)  # Update the number using Pascal's Triangle formula
    print()  # Move to the next line after completing the row

These patterns can be adjusted by modifying the range or loop values.
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Subhendu Mohapatra

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