Python pattern challenge - Day 7

 

a=[]

for i in range(7):

    a.append([])

    for j in range(7):

        if i==0 or i==6 or i+j==6 or i==j:

            a[i].append("*")

        else:

            a[i].append(" ")

for i in range(7):

    print(*a[i])

Explanation: 

 Let's break down the code step by step:

a = []: This line initializes an empty list named a. This list will eventually hold the elements of the 2D array or matrix.

The outer loop: for i in range(7):

This loop iterates over values from 0 to 6 (inclusive).

For each value of i, a new empty list is appended to the list a. This effectively initializes a new row in the matrix.

The inner loop: for j in range(7):

This loop iterates over values from 0 to 6 (inclusive), representing columns within each row.

For each cell in the matrix (each combination of i and j), the following condition is checked:

The if condition:

If i is 0 or 6 (first or last row), or if the sum of i and j equals 6 (indicating the anti-diagonal), or if i equals j (indicating the main diagonal), then a star (*) is appended to the current row (a[i]). Otherwise, a space is appended.

After completing the inner loop for each i, a contains a 2D list representing a matrix where stars (*) are placed along the main diagonal, anti-diagonal, and the first and last rows.

The final loop: for i in range(7):

This loop iterates over the rows of the matrix.

For each row, the print(*a[i]) statement prints the elements of that row separated by spaces.

Overall, this code generates a 7x7 matrix filled with spaces and stars according to the conditions specified, and then prints the matrix row by row.