Generates a spiral pattern

spiral.py

# This program generates a number spiral based on number entered by user

#   Example: If input is 4, output is

#   01 02 03 04
#   12 13 14 05
#   11 16 15 06
#   10 09 08 07



i = 0      # Holds the position of row
j = 0      # Holds the position of column 
di = 0     # Defines how i should change
dj = 1     # Defines how j should change
spiral = 0 # Keeps count of spirals

num = int(input('Enter a number: '))
sq = num**2

# Create a square matrix of order num x num
matrix = [ [0 for col in range(num)] for row in range(num)]

# Pattern generation
for val in range(1, sq+1):
    # Set the value in the matrix
    matrix[i][j] = val

    # Control reaches top right
    if j == num-1-spiral:
        dj = 0
        di = 1 # Start moving down

    # Control reaches bottom right
    if i == num-1-spiral and j == num-1-spiral:
        dj = -1 # Start moving left
        di = 0
    
    # Control reaches bottom left
    if i == num-1-spiral and j == spiral:
        di = -1 # Start moving up
        dj = 0
    
    # Control reaches top left
    if i == spiral+1 and j == spiral:
        di = 0
        dj = 1 # start moving right again
        
        spiral += 1 # update spiral by 1, as 1 round of spiral is complete now
    
    # Update values of i, j for next iteration
    i += di
    j += dj



# Output section
for row in matrix:
    for val in row:
        print("{:02d}".format(val), end=' ')
    print()