Python Code Example: simple pattern

This Python code snippet uses nested for loops to generate a pattern of numbers. The outer loop iterates i from 0 to 8. For each value of i, the inner loop iterates j from 0 to i-1, printing the value of i on the same line without a newline character. After the inner loop completes, the print() statement adds a newline, creating a new line for the next value of i. The result is a pattern where each line contains the number i repeated i times, starting from 1 up to 8.

Code Example

for i in range(0, 9):
    for j in range(0, i):
        print(i, end="")
    print()

Output

1
22
333
4444
55555
666666
7777777
88888888

Code Explanation

Outer for Loop

The outer for loop runs with the variable i iterating from 0 to 8 (inclusive). The range(0, 9) function generates a sequence of numbers starting from 0 up to, but not including, 9.

for i in range(0, 9):
    # The rest of the code

Here’s what the sequence looks like: [0, 1, 2, 3, 4, 5, 6, 7, 8].

Inner for Loop

The inner for loop runs with the variable j iterating from 0 to i (exclusive). This means for each value of i, the inner loop runs i times.

for j in range(0, i):
    print(i, end="")

• For i = 0, the inner loop does not execute because range(0, 0) produces an empty sequence.
• For i = 1, the inner loop runs once (j = 0), and it prints 1.
• For i = 2, the inner loop runs twice (j = 0 and j = 1), and it prints 2 two times.
• And so on.

The print(i, end="") statement prints the value of i without a newline at the end (because of the end="" argument), so it prints on the same line.

print() Statement

After the inner loop completes, the print() statement executes. This statement prints a newline character, moving the cursor to the next line for the subsequent iterations of the outer loop.