[Tutor] Fw: Traceback

[niyanaxx95 at gmail.com]

I get this message:

Traceback (most recent call last):
  File "C:\Program Files (x86)\Wing IDE 101 5.0\src\debug\tserver\_sandbox.py", line 87, in <module>
  File "C:\Program Files (x86)\Wing IDE 101 5.0\src\debug\tserver\_sandbox.py", line 20, in main
  File "C:\Program Files (x86)\Wing IDE 101 5.0\src\debug\tserver\_sandbox.py", line 70, in tilesForSize
builtins.TypeError: unsupported operand type(s) for -: 'NoneType' and 'int'







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From: Ni'Yana Morgan
Sent: ‎Tuesday‎, ‎November‎ ‎18‎, ‎2014 ‎4‎:‎42‎ ‎PM
To: tutor at phython.org





Trying to figure out why I get a traceback on line 20, 70, and 87. Please Help!!!!




Problem Statement: ​

1. The first and last tile in the first row shall be black.
2. The first and last tile in the first column shall be black.
3. The tiles will alternate between black and lemon





The task is to write a function to compute and print:
 the number of tiles needed in the first row (the number of columns)
 the number of tiles needed in the first column (the number of rows)
 the total number of tiles needed to cover the floor
 the gap at the end of each row
 the gap at the end of each column
And then print (using a function):
1. The colored tile pattern to a graphics window
a. The pattern should be printed centered in the graphics window, with equal gaps at 
the end of each row, and equal gaps at the end of each column

Use functions to:
1. Read and validate the input values
a. Width
b. Length
c. Tile Size
2. Compute the number of rows, columns, total tiles required, and the size of the gaps at the 
end of each row and column
3. Print the tile pattern










My Code:


# Import graphics from module
from graphics import GraphicsWindow




tileSize = 0




def main() :
    
    # Define global variables
    tilesInRow = 0
    tilesInCol = 0
    gapX = 0
    gapY = 0
    
    # Input room width
    roomWidth = getNumber(100, 500, "Enter a room width between 100 and 500: ", "")
    roomLength = getNumber(100, 450, "Enter a room length between 100 and 450: ", "")
    tileSize = getNumber(20, 50, "Enter a tile size between 20 and 50: ", "")
    
    numCols = tilesForSize(roomWidth)
    print("The total number of Columns:", numCols)
    numRows = tilesForSize(roomLength)
    print("The total number of Rows:", numRows)
    
    # Print the total number of tiles
    print("The total number or Tiles: %d" %(numCols * numRows))
    
    # Calculate the gap
    # the gap = (the total width - the number of tiles * tile width / 2
    
    gapX = calculateGap(roomWidth, numCols)
    gapY = calculateGap(roomLength, numRows)
    
    # Print the gaps
    print("The gap at each end of a row is: %.1f" % (gapX))
    print("The gap at each end of a column is: %.1f" % (gapY))
    
    # Draw graphics window
    win = GraphicsWindow(roomWidth, roomLength)
    canvas = win.canvas()
    
    # Draw the checkered surface
    for row in range(numRows) :
        # If the row is even
        if row % 2 == 0 :
            # If the column is even set color to black, if odd yellow
            drawRow(canvas, row, gapX, numCols, gapY, "black", "yellow")




        # If the row is odd
        else:
            # If the column is even set color to yellow, if odd black
            drawRow(canvas, row, gapX, numCols, gapY, "yellow", "black")      
          
    win.wait()
    
def getNumber(minBound, maxBound, msg, err_msg) :
    num = minBound - 1
    while num < minBound or num > maxBound :
        if(msg == "") :
            num = float(input("Enter a number between %f and %f: " % (minBound, maxBound)))
        else :
            num = float(input(msg))
        if num < minBound or num > maxBound :
            if err_msg == "" :
                print("Invalid input.")   
            else:
                print(err_msg) 




def tilesForSize(size) : 
    pairs = int((size - tileSize) // int(2 * tileSize))
    num = int(1 + (2 * pairs))
    return num




def calculateGap(size, num) :
    return (size - num * tileSize) / 2




def drawRow(canvas, row, gapX, numCols, gapY, color1, color2) :
    for col in range(numCols) :
        if col % 2 == 0 :
            canvas.setColor(color1)
        else:
            canvas.setColor(color2)
        # Draw the actual rectangle
        canvas.drawRect(row * tileSize + gapX, col * tileSize + gapY, tileSize, tileSize)
    return 
    
main()
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