Mastering Python: 30 Engaging Exercises to Learn Nested Loops
Nested loops are a key concept in Python, crucial for tackling complex problems that require layered data processing. This blog offers 30 diverse pattern-building exercises that will help you understand and master nested loops in Python. Whether you’re starting out or looking to polish your skills, these exercises are designed to enhance your coding ability and boost your problem-solving techniques in Python.
Pattern Exercises
1. Solid Square Pattern
Create a solid square of asterisks.
n = 5
for i in range(n):
for j in range(n):
print('*', end=' ')
print()Output:
* * * * *
* * * * *
* * * * *
* * * * *
* * * * *2. Hollow Square Pattern
Design a square frame using asterisks.
n = 5
for i in range(n):
for j in range(n):
if i == 0 or i == n - 1 or j == 0 or j == n - 1:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * * * *
* *
* *
* *
* * * * *3. Increasing Triangle Pattern
Generate a right-aligned triangle using asterisks.
n = 5
for i in range(1, n+1):
for j in range(i):
print('*', end=' ')
print()Output:
*
* *
* * *
* * * *
* * * * *4. Decreasing Triangle Pattern
Create a right-aligned triangle with asterisks in reverse order.
n = 5
for i in range(n, 0, -1):
for j in range(i):
print('*', end=' ')
print()Output:
* * * * *
* * * *
* * *
* *
*5. Right-angled Triangle Pattern (Left)
Construct a left-aligned triangle.
n = 5
for i in range(n):
print('* ' * (i+1))Output:
*
* *
* * *
* * * *
* * * * *6. Downward Triangle Mirror Pattern
Build a mirrored triangle descending from right to left.
n = 5
for i in range(n):
print(' ' * i + '* ' * (n-i))Output:
* * * * *
* * * *
* * *
* *
*7. Pyramid Pattern
Create a centered pyramid.
n = 5
for i in range(n):
print(' ' * (n-i-1) + '* ' * (i+1))Output:
*
* *
* * *
* * * *
* * * * *8. Inverted Pyramid Pattern
Design an inverted pyramid.
n = 5
for i in range(n):
print(' ' * i + '* ' * (n-i))Output:
* * * * *
* * * *
* * *
* *
*Here are the remaining 22 pattern exercises with their Python code and respective outputs. These exercises cover a variety of pattern styles, progressing in complexity and helping further reinforce your understanding of nested loops in Python.
9. Diamond Pattern
Create a diamond shape with asterisks.
n = 5
for i in range(n):
print(' ' * (n-i-1) + '* ' * (i+1))
for i in range(n-1):
print(' ' * (i+1) + '* ' * (n-i-1))Output:
*
* *
* * *
* * * *
* * * * *
* * * *
* * *
* *
*10. X Pattern
Form an ‘X’ shape using asterisks.
n = 5
for i in range(n):
for j in range(n):
if i == j or i + j == n - 1:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* *
* *
*
* *
* *11. Hourglass Pattern
Create an hourglass pattern using asterisks.
n = 5
for i in range(n, 0, -1):
print(' ' * (n-i) + '* ' * i)
for i in range(2, n+1):
print(' ' * (n-i) + '* ' * i)Output:
* * * * *
* * * *
* * *
* *
*
* *
* * *
* * * *
* * * * *12. Right Arrow Pattern
Construct a right arrow with asterisks.
n = 5
for i in range(n):
if i < n // 2:
print('* ' * (i+1))
else:
print('* ' * (n-i))Output:
*
* *
* * *
* *
*13. Left Arrow Pattern
Create a left arrow pattern.
n = 5
for i in range(n):
if i <= n // 2:
print(' ' * (n//2 - i) + '* ' * (i+1))
else:
print(' ' * (i - n//2) + '* ' * (n-i))Output:
*
* *
* * *
* *
*14. Checkerboard Pattern
Generate a checkerboard pattern of asterisks.
n = 5
for i in range(n):
for j in range(n):
if (i+j) % 2 == 0:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * * * *
* * * *
* * * * *
* * * *
* * * * *15. Zigzag Pattern
Create a zigzag pattern using asterisks.
n = 9
for i in range(3):
for j in range(n):
if (j % 4 == 0 and i == 0) or (j % 4 == 2 and i == 2) or (j % 4 == 1 or j % 4 == 3 and i == 1):
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * *
* * * *
* * 16. Plus Sign Pattern
Form a plus sign (+) shape.
n = 5 # n must be odd
mid = n // 2
for i in range(n):
for j in range(n):
if i == mid or j == mid:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
*
*
* * * * *
*
* 17. Cross Pattern
Create a cross (X) pattern using asterisks.
n = 5 # n should be odd
for i in range(n):
for j in range(n):
if i == j or i + j == n - 1:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* *
* *
*
* *
* *18. Vertical Lines Pattern
Generate vertical lines using aster
isks.
n = 5
for i in range(n):
for j in range(n):
if j % 2 == 0:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * *
* * *
* * *
* * *
* * *19. Staircase Pattern (Ascending)
Build an ascending staircase pattern.
n = 5
for i in range(1, n+1):
print((' ' * (n-i)) + ('# ' * i))Output:
#
# #
# # #
# # # #
# # # # #20. Staircase Pattern (Descending)
Create a descending staircase pattern.
n = 5
for i in range(n, 0, -1):
print((' ' * (n-i)) + ('# ' * i))Output:
# # # # #
# # # #
# # #
# #
#21. Alternating Pattern
Design a pattern with alternating asterisks and dashes.
n = 5
for i in range(n):
for j in range(n):
if (i + j) % 2 == 0:
print('*', end=' ')
else:
print('-', end=' ')
print()Output:
* - * - *
- * - * -
* - * - *
- * - * -
* - * - *22. Spiral Pattern
Create a spiral pattern inside a matrix.
n = 5
a = [[' ' for x in range(n)] for y in range(n)]
x, y = 0, 0
dx, dy = 0, 1
for i in range(n**2):
a[x][y] = '*'
if a[(x+dx)%n][(y+dy)%n] == '*':
dx, dy = dy, -dx
x, y = x + dx, y + dy
for row in a:
print(' '.join(row))Output:
* * * * *
*
* * * *
* * *
* * * * *23. Swastika Pattern
Generate a swastika pattern (commonly used in ancient cultures).
n = 7 # n must be odd
mid = n // 2
for i in range(n):
for j in range(n):
if (i == mid or j == mid) or (i < mid and j == 0) or (j < mid and i == 0) or (i > mid and j == n-1) or (j > mid and i == n-1):
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * * * * * *
* *
* * * * * *
*
* * * * * *
* *
* * * * * * *24. Interlocking Squares Pattern
Design a pattern with two interlocking squares.
n = 8 # Even number larger than 4
for i in range(n):
for j in range(n):
if i == j or i + j == n - 1 or i == 0 or j == 0 or i == n - 1 or j == n - 1:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * * * * * * *
* * * *
* * * *
* * * *
* * * *
* * * *
* * * *
* * * * * * * *25. Circular Pattern
Create a circular pattern using asterisks (approximation).
n = 10 # Larger for a more rounded appearance
for i in range(n):
for j in range(n):
if ((i-n//2)**2 + (j-n//2)**2 < (n//2)**2):
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * * *
* * * * * * * *
* * * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * *
* * * * *
* * * * * * * * *
* * * * * * * *
* * * *26. Heart Pattern
Form a heart shape using asterisks.
for row in range(6):
for col in range(7):
if (row == 0 and col % 3 != 0) or (row == 1 and col % 3 == 0) or (row - col == 2) or (row + col == 8):
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
* * * *
* * * *
* *
* *
* *
*Here are four additional pattern-building exercises using nested loops in Python, each complete with Python code and the corresponding output:
27. Left Diagonal Pattern
Create a left diagonal pattern using asterisks.
n = 5
for i in range(n):
for j in range(n):
if i == j:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
*
*
*
*
* 28. Right Diagonal Pattern
Construct a right diagonal pattern from top right to bottom left.
n = 5
for i in range(n):
for j in range(n):
if i + j == n - 1:
print('*', end=' ')
else:
print(' ', end=' ')
print()Output:
*
*
*
*
* 29. Triangle with Numbers
Generate a right-aligned triangle pattern using consecutive numbers instead of asterisks.
n = 5
num = 1
for i in range(1, n+1):
for j in range(i):
print(num, end=' ')
num += 1
print()Output:
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15 30. Sandglass Pattern
Create a sandglass or hourglass pattern using asterisks.
n = 5
for i in range(n, 0, -1):
print(' ' * (n - i) + '* ' * i)
for i in range(2, n + 1):
print(' ' * (n - i) + '* ' * i)Output:
* * * * *
* * * *
* * *
* *
*
* *
* * *
* * * *
* * * * * These exercises provide a variety of patterns to explore, from simple diagonals to more complex numerical and reflective designs, enhancing your proficiency with nested loops in Python.
