Master 10 Star Patterns in Python Like a Pro!

Pattern programs play a crucial role in coding interviews, helping candidates strengthen their logical thinking and problem-solving skills. They test a programmer’s ability to use loops, conditions, and print statements efficiently.

One of the biggest challenges in pattern programming is reducing time complexity. While most star patterns are implemented using nested loops, a more optimized approach involves using a single loop to generate the same patterns. This method improves efficiency and enhances a coder’s ability to think creatively. To Learn star patterns using two loops checkout this master star patterns using two for loops.

In this blog, we will explore 10 different star pattern programs that can be implemented using a single for loop in Python. Each program includes:

• Problem Statement
• Code with Comments
• Step-by-Step Explanation
• Expected Output

By the end, you’ll have a solid grasp of single-loop star pattern logic, making your Python coding skills stand out. Let’s get started!

Watch This Video Tutorial on Star Patterns in Python

1. Printing a Single Star (*)

Code

print("*")

Explanation

• print("*") simply prints a single * on the screen.
• The output is:

Output

*

2. Printing 5 Stars in One Line

Code

for i in range(5):
    print("*", end=" ")

Explanation

for i in range(5)

• This loop runs 5 times.
• i starts from 0 and goes up to 4.

Iteration Breakdown:

• Iteration 1:
  • i = 0
  • Prints: * with a space → *
• Iteration 2:
  • i = 1
  • Prints: * with a space → * *
• Iteration 3:
  • i = 2
  • Prints: * with a space → * * *
• Iteration 4:
  • i = 3
  • Prints: * with a space → * * * *
• Iteration 5:
  • i = 4
  • Prints: * with a space → * * * * *

Output

* * * * * 

Summary

• Each loop prints one * followed by a space.
• After 5 loops, all * are printed in a single line.

3. Printing Stars in 5 Lines (Vertical)

Code

for i in range(5):
    print("*")

Explanation

for i in range(5)

• This is a for loop that runs 5 times.
• i starts from 0 and goes up to 4.

Iteration Breakdown:

• Iteration 1:
  • i = 0
  • Prints: * and moves to the next line.
• Iteration 2:
  • i = 1
  • Prints: * and moves to the next line.
• Iteration 3:
  • i = 2
  • Prints: * and moves to the next line.
• Iteration 4:
  • i = 3
  • Prints: * and moves to the next line.
• Iteration 5:
  • i = 4
  • Prints: * and moves to the next line.

Output

*
*
*
*
*

Summary

• Since there is no end=" ", the default behavior of print() moves the cursor to the next line after printing each *.
• Hence, all * are printed vertically (one per line).

4. Printing a Right-Angled Triangle Star Pattern

Code

for i in range(1, 6):
    print("*" * i)

Explanation

for i in range(1, 6)

• This is a for loop that runs 5 times.
• i starts from 1 and goes up to 5 (since range(1, 6) generates values from 1 to 5).

Iteration Breakdown:

• Iteration 1:
  • i = 1
  • Prints: * → *
• Iteration 2:
  • i = 2
  • Prints: ** → **
• Iteration 3:
  • i = 3
  • Prints: *** → ***
• Iteration 4:
  • i = 4
  • Prints: **** → ****
• Iteration 5:
  • i = 5
  • Prints: ***** → *****

Output

Summary

• "*" * i → Repeats the * symbol i times.
• As i increases, the number of * increases, forming a right-angled triangle pattern.

5. Printing a Right-Aligned Triangle Star Pattern

Code

n = 5
for i in range(1, n + 1):
    print(" " * (n - i) + "*" * i)

Explanation

for i in range(1, n + 1)

• This loop runs 5 times, starting from 1 and going up to 5 (since n + 1 = 6, but range() excludes the upper limit).
• i takes values: 1, 2, 3, 4, 5.

Iteration Breakdown:

• Iteration 1:
  • i = 1
  • 5 - 1 = 4 spaces → " "
  • * → 1 star
• Iteration 2:
  • i = 25 - 2 = 3 spaces → " "** → 2 stars
• Iteration 3:
  • i = 35 - 3 = 2 spaces → " "*** → 3 stars
• Iteration 4:
  • i = 4
  • 5 - 4 = 1 space → " "
  • **** → 4 stars

• Iteration 5:
  • i = 5
  • 5 - 5 = 0 spaces → ""
  • ***** → 5 stars

Summary

• " " * (n - i) shifts the stars to the right.
• "*" * i increases the number of stars in each row.
• Together, they create a right-aligned triangle pattern.

6. Printing a Reverse Right-Angled Triangle Star Pattern

Code

for i in range(5, 0, -1):
    print("*" * i)

Explanation

1. for i in range(5, 0, -1)
2. This loop starts from 5 and goes down to 1.
3. 5 is the starting value, 0 is the stopping value (exclusive), and -1 decreases the value by 1 in each iteration.

Iteration Breakdown:

• Iteration 1:
  • i = 5
  • Prints: *****
• Iteration 2:
  • i = 4
  • Prints: ****
• Iteration 3:
  • i = 3
  • Prints: ***
• Iteration 4:
  • i = 2
  • Prints: **
• Iteration 5:
  • i = 1
  • Prints: *

Output

Summary

• range(5, 0, -1) decreases i by 1 in each iteration.
• "*" * i prints the stars, reducing by one each time, creating an inverted triangle pattern.

7. Printing a Right-Aligned Reverse Triangle Star Pattern

Code

n = 5
for i in range(n, 0, -1):
    print(" " * (n - i) + "*" * i)

Explanation

for i in range(n, 0, -1)

• This loop starts from n (which is 5) and goes down to 1.
• 0 is the stopping point (exclusive), and -1 decreases the value by 1 in each iteration.

" " * (n - i)

• Adds spaces before the stars.
• n - i calculates the number of leading spaces needed to right-align the pattern.

"*" * i

• Prints i stars.
• As i decreases, the number of stars also decreases, forming an inverted right-aligned pattern.

Iteration Breakdown:

• Iteration 1:
  • i = 5
  • n - i = 5 - 5 = 0 spaces → ""
  • ***** → 5 stars
• Iteration 2:
  • i = 4
  • n - i = 5 - 4 = 1 space → " "
  • **** → 4 stars
• Iteration 3:
  • i = 3
  • n - i = 5 - 3 = 2 spaces → " "
  • *** → 3 stars
• Iteration 4:
  • i = 2
  • n - i = 5 - 2 = 3 spaces → " "
  • ** → 2 stars
• Iteration 5:
  • i = 1
  • n - i = 5 - 1 = 4 spaces → " "
  • * → 1 star

Summary

• " " * (n - i) adds leading spaces to shift stars to the right.
• "*" * i prints decreasing stars in each row.
• Together, they create an inverted right-aligned triangle pattern.

8. Creating a Pyramid Star Pattern

Code

n = 5
for i in range(1, n + 1):
    print(" " * (n - i) + "*" * (2 * i - 1))

Explanation

for i in range(1, n + 1)

• This loop runs 5 times, starting from 1 to 5 (since n + 1 is 6 but excluded in range()).
• i increases by 1 in each iteration.

" " * (n - i)

• Adds leading spaces to shift the stars to the right.
• n - i calculates the number of spaces required to center-align the stars.

"*" * (2 * i - 1)

• Prints an odd number of stars.
• 2 * i - 1 increases by 2 with each iteration, printing 1, 3, 5, 7, and 9 stars.

Iteration Breakdown:

• Iteration 1:
  • i = 1
  • n - i = 5 - 1 = 4 spaces → " "
  • 2 * 1 - 1 = 1 star → *
• Iteration 2:
  • i = 2
  • n - i = 5 - 2 = 3 spaces → " "
  • 2 * 2 - 1 = 3 stars → ***
• Iteration 3:
  • i = 3
  • n - i = 5 - 3 = 2 spaces → " "
  • 2 * 3 - 1 = 5 stars → *****
• Iteration 4:
  • i = 4
  • n - i = 5 - 4 = 1 space → " "
  • 2 * 4 - 1 = 7 stars → *******
• Iteration 5:
  • i = 5
  • n - i = 5 - 5 = 0 spaces → ""
  • 2 * 5 - 1 = 9 stars → *********

Summary

• " " * (n - i) adds leading spaces to center the stars.
• "*" * (2 * i - 1) prints increasing stars in an odd pattern.
• Together, they create a pyramid pattern.

Output

9. Reversing a Pyramid Star Pattern

Code

n=5
for i in range(n - 1, 0, -1):
    print(" " * (n - i) + "*" * (2 * i - 1))

Explaination

for i in range(n - 1, 0, -1)

• This loop starts from n - 1 (which is 4) and goes down to 1.
• 0 is the stopping point (exclusive), and -1 decreases the value of i by 1 in each iteration.

" " * (n - i)

• Adds leading spaces to center-align the stars.
• n - i calculates the number of spaces required before the stars.

"*" * (2 * i - 1)

• Prints an odd number of stars.

Iteration Breakdown:

• Iteration 1:
  • i = 4
  • n - i = 5 - 4 = 1 space → " "
  • 2 * 4 - 1 = 7 stars → *******
• Iteration 2:
  • i = 3
  • n - i = 5 - 3 = 2 spaces → " "
  • 2 * 3 - 1 = 5 stars → *****
• Iteration 3:
  • i = 2
  • n - i = 5 - 2 = 3 spaces → " "
  • 2 * 2 - 1 = 3 stars → ***
• Iteration 4:
  • i = 1
  • n - i = 5 - 1 = 4 spaces → " "
  • 2 * 1 - 1 = 1 star → *

Output

Summary

• " " * (n - i) adds spaces to center the stars.
• "*" * (2 * i - 1) prints decreasing stars in an odd star pattern.
• Together, they create an inverted pyramid star pattern.

10. Creating a Diamond Star Pattern

Code

n = 5
for i in range(1, n + 1):
    print(" " * (n - i) + "*" * (2 * i - 1))

for i in range(n - 1, 0, -1):
    print(" " * (n - i) + "*" * (2 * i - 1))

Explanation

First Loop

• for i in range(1, n + 1)
  • This loop starts from 1 and goes up to 5.
  • It prints the top half (pyramid) of the diamond.
• " " * (n - i)
  • Adds spaces before the stars to center them.
• "*" * (2 * i - 1)

Iteration Breakdown (First Loop):

• i = 1, n - i = 4 → 4 spaces + 1 star → *
• i = 2, n - i = 3 → 3 spaces + 3 stars → ***
• i = 3, n - i = 2 → 2 spaces + 5 stars → *****
• i = 4, n - i = 1 → 1 space + 7 stars → *******
• i = 5, n - i = 0 → 0 spaces + 9 stars → *********

Second Loop

1. for i in range(n - 1, 0, -1)
   • This loop starts from n - 1 (which is 4) and goes down to 1.
   • It prints the bottom half (inverted pyramid) of the diamond.
2. " " * (n - i)
   • Adds spaces before the stars to center them.
3. "*" * (2 * i - 1)
   • Prints an odd number of stars in decreasing order.

Iteration Breakdown (Second Loop):

• i = 4, n - i = 1 → 1 space + 7 stars → *******
• i = 3, n - i = 2 → 2 spaces + 5 stars → *****
• i = 2, n - i = 3 → 3 spaces + 3 stars → ***
• i = 1, n - i = 4 → 4 spaces + 1 star → *

Output

Summary

• The first loop creates the star pattern of top half (pyramid).
• The second loop creates the star pattern of bottom half (inverted pyramid).
• Together, they form a diamond star pattern.

Optimization Tips

• In order to efficiently make star pattern, use string multiplication (*).
• To prevent needless conditions within loops, precompute line breaks.
• Make use of mathematical methods to dynamically calculate the locations of stars and space.
• Reduce code duplication by aiming for succinct logic.

Conclusion

Learning Python star patterns improves one’s capacity for reasoning and problem-solving. Coding efficiency is increased and execution time is optimised when they are implemented in a single loop.

Try out different designs, adjust the reasoning, and practise these patterns! Do you have any queries? Please leave a remark below.

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