为什么我在 python 中的方形绘图函数没有向下移动一行？

Question

from graphics import *

def patch2():
    win = GraphWin("pattern", 100,100)
    TLX = 0
    TLY = 0
    BRX = 20
    BRY = 20
    for i in range(5):
        for i in range(5):
            r = Rectangle(Point(TLX,TLY), Point(BRX,BRY))
            r.draw(win)
            BRX += 20
            TLX += 20
            print(BRY)
        BRY = BRY + 20
        TLY = TLY + 20

patch2()

the purpose of the code is to draw 25 boxes (5x5). The second for loop works, and draws 5 boxes across the top row of the graphics window, but it doesn't do the other 4 rows. TL AND BR stand for top left and bottom right (x and y coordinates)

Answer 1

Simply adding TLX = 0 after the inner for loop fixes the drawing but also resetting BRX = 20 fixes the code. We can simplify things a bit by tossing the BR* variables:

from graphics import *

def patch2():
    tl_x, tl_y = 0, 0

    for _ in range(5):
        for _ in range(5):
            r = Rectangle(Point(tl_x, tl_y), Point(tl_x + 20, tl_y + 20))
            r.draw(win)
            tl_x += 20

        tl_x = 0
        tl_y += 20

win = GraphWin("pattern", 100, 100)

patch2()

Or, we can make use of the Point classes inherited methods and make the design more point-oriented:

from graphics import *

def patch2():
    top_left = Point(0, 0)
    bottom_right = Point(20, 20)

    for _ in range(5):
        for _ in range(5):
            r = Rectangle(top_left, bottom_right)
            r.draw(win)
            top_left.move(20, 0)
            bottom_right.move(20, 0)

        top_left.move(-100, 20)
        bottom_right.move(-100, 20)

win = GraphWin("pattern", 100, 100)

patch2()