sudoku_puzzle.py

from PIL import Image, ImageDraw, ImageFont
import random

def create_puzzle():  
  base  = 3
  side  = base*base

  # pattern for a baseline valid solution
  def pattern(r,c): return (base*(r%base)+r//base+c)%side

  # randomize rows, columns and numbers (of valid base pattern)
  from random import sample
  def shuffle(s): return sample(s,len(s)) 
  rBase = range(base) 
  rows  = [ g*base + r for g in shuffle(rBase) for r in shuffle(rBase) ] 
  cols  = [ g*base + c for g in shuffle(rBase) for c in shuffle(rBase) ]
  nums  = shuffle(range(1,base*base+1))

  # produce board using randomized baseline pattern
  board = [ [nums[pattern(r,c)] for c in cols] for r in rows ]
  # print(board)
  
  # Remove some of the numbers to create the puzzle
  for i in range(9):
    for j in range(9):
      if random.random() < 0.5:
        board[i][j] = 0

  return board


def draw(puzzle):
  # Create a new image with a white background
  img = Image.new('RGB', (360, 360), color=(255, 255, 255))

  # Load a font
  font = ImageFont.truetype('arial.ttf', 36)

  # Get a drawing context
  draw = ImageDraw.Draw(img)

  # Draw the grid lines
  for i in range(10):
    # Vertical lines
    x = 40 * i
    y1 = 0
    y2 = 400
    if(i%3==0):
      draw.line((x, y1, x, y2), fill=(0, 0, 0), width=6)
    else:
      draw.line((x, y1, x, y2), fill=(0, 0, 0), width=2)

    # Horizontal lines
    x1 = 0
    x2 = 400
    y = 40 * i
    if(i%3==0):
      draw.line((x1, y, x2, y), fill=(0, 0, 0), width=6)
    else:
      draw.line((x1, y, x2, y), fill=(0, 0, 0), width=2)

  # Draw the numbers
  for i in range(9):
    for j in range(9):
      # Get the center position of the cell
      x = 41 * j + 5
      y = 40 * i + 5

      # Get the number to draw
      n = puzzle[i][j]

      # Draw the number
      if n != 0:
        draw.text((x, y), str(n), font=font, fill=(0, 0, 0))

  return img


# Declare how many puzzle you want to create
for i in range(4):
  # Generate a random puzzle
  puzzle = create_puzzle()

  # Draw the puzzle
  img = draw(puzzle)

  # # Save the image to a file
  img.save('sudoku_{}.png'.format(i))