Screen Won't Open When Drawing Checker Board Using Turtle

Question

I am trying to draw a checker board using the Turtle library and am running into an error where the board window does not open. It was working at the beginning of my session about 30 minutes ago but, I changed some stuff and want to know why it changed.

Here is my code:

##This program draws a checkboard using the turtle library
import turtle  

#below initiates the turtle pen and screen
penMain = turtle.Turtle()   
turtleMain = turtle.Screen() 
   
def turtleBoard(): 
   
    for x in range(4): 
        penMain.forward(30) 
        penMain.left(90) 
   
    penMain.forward(30)  
    turtleMain.setup(600, 600) 
    penMain.speed(50) 
        
    for a in range(8): 
        penMain.up()  
        penMain.setpos(0, 30 * a) 
        penMain.down() 
        for x in range(8): 
            if (a + x)% 2 == 0: 
                squareColor = 'black'
            else: 
                squareColor = 'white'
       
                penMain.fillcolor(squareColor)  
                penMain.begin_fill() 
                turtleBoard()  
                penMain.end_fill() 
    

I believe this code works besides my one error! Thank you all for your help in advance!

Answer 1

Now that we've seen that your code can be made to work, let's consider stamping instead of drawing to make it work more simply and more quickly:

from turtle import Screen, Turtle

SQUARES_PER_EDGE = 8
SQUARE_SIZE = 30  # in pixels
OFFSET = SQUARE_SIZE * (SQUARES_PER_EDGE / 2) - SQUARE_SIZE/2  # center the board

CURSOR_SIZE = 20

def turtleBoard():
    turtle.shape('square')
    turtle.shapesize(SQUARE_SIZE / CURSOR_SIZE)
    turtle.penup()

    for y in range(SQUARES_PER_EDGE):
        for x in range(SQUARES_PER_EDGE):
            turtle.goto(x * SQUARE_SIZE - OFFSET, y * SQUARE_SIZE - OFFSET)
            turtle.fillcolor('black' if y % 2 == x % 2 else 'white')
            turtle.stamp()

screen = Screen()
screen.setup(600, 600)

turtle = Turtle()
turtle.speed('fastest')  # because I have no patience

turtleBoard()

screen.exitonclick()

Answer 2

I can't say what changes you made to get your current code, but this code seems to be working:

##This program draws a checkboard using the turtle library
import turtle  

#below initiates the turtle pen and screen
penMain = turtle.Turtle()   
turtleMain = turtle.Screen() 
   
def turtleBoard(): 
    
    penMain.forward(30)  
    turtleMain.setup(600, 600) 
    penMain.speed(50) 
        
    for a in range(8): 
        for x in range(8): 
            penMain.up()  
            penMain.setpos(30 * x, 30 * a) 
            penMain.down() 
            penMain.begin_fill() 
            for xx in range(4): 
                penMain.forward(30) 
                penMain.left(90) 
            if a%2 == x%2: 
                squareColor = 'black'
            else: 
                squareColor = 'white'
       
            penMain.fillcolor(squareColor)  
            penMain.end_fill() 
            
turtleBoard()  
turtle.done()

Answer 3

I lined up the indent of the bottom 4 lines with the last 'else' statement and it worked. Thank you guys!