Python: 如何让海龟永远不会越线

Question

我正在尝试编写一个 python 程序，使海龟要么向前移动，向左转然后移动，要么向右转然后随机移动，而不会越过它自己先前绘制的线。它必须留在屏幕内并在完成最可能的移动后清除并重新启动。据我所知：

import turtle
positions=[]

while 'x':
    count=132
    for x in range (132):
        count-=1
        print(count)
        move = randint(1,3)

        if move == 1:
            turtle.fd(50)
        if move == 2:
            turtle.rt(90)
            turtle.fd(50)
        if move == 3:
            turtle.lt(90)
            turtle.fd(50)

        if turtle.xcor()>290:
            turtle.rt(180)
            turtle.fd(50)
        if turtle.xcor()<-290:
            turtle.rt(180)
            turtle.fd(50)
        if turtle.ycor()>240:
            turtle.rt(180)
            turtle.fd(50)
        if turtle.ycor()<-240:
            turtle.rt(180)
            turtle.fd(50)
    turtle.clear()

如何让它记住它的位置而不是越过它们？非常感谢！

Answer 1

下面是我尝试解决你的自主乌龟问题的尝试。我选择了一个 set() 来跟踪访问过的位置，但也将海龟强制放到一个网格上以确保只能访问一组有限的点。我不喜欢你在撞墙时做 180 度转弯的方法，因为这只会让你原路返回并失败——相反，我的乌龟试图避免撞墙。

我用一只隐形的海龟克隆体来"test the waters" 看一招好坏。如果没有好的动作，它会放弃、重置并重新开始。您必须关闭 window 才能终止程序：

import turtle
from random import shuffle

WIDTH, HEIGHT = 600, 500

INCREMENT = 50

TURTLE_WIDTH = 20

X, Y = 0, 1

def dot_round(x, base=INCREMENT):
    return int(base * round(float(x) / base))

turtle.setup(WIDTH, HEIGHT)

turtle.shape("turtle")

while True:
    positions = set()

    while True:

        position = (dot_round(turtle.xcor()), dot_round(turtle.ycor()))  # coerce position to grid

        if position in positions:
            break  # collision with line

        positions.add(position)

        turtle.setposition(position)  # coerce turtle back onto our grid

        moves = list(range(3))

        shuffle(moves)

        clone = None

        for move in moves:
            clone = turtle.clone()  # use an invisible clone to test the waters
            clone.hideturtle()
            clone.penup()

            if move == 1:
                clone.right(90)
            elif move == 2:
                clone.left(90)

            clone.forward(INCREMENT)

            position = (dot_round(clone.xcor()), dot_round(clone.ycor()))

            if position[X] <= TURTLE_WIDTH//2 - WIDTH//2 or position[X] > WIDTH//2 - TURTLE_WIDTH//2:
                continue  # avoid collision with wall

            if position[Y] <= TURTLE_WIDTH//2 - HEIGHT//2 or position[Y] > HEIGHT//2 - TURTLE_WIDTH//2:
                continue  # avoid collision with wall

            if position not in positions:
                break

        else:  # no break
            break  # accept the inevitable, there's no good move

        turtle.setheading(clone.heading())
        turtle.forward(INCREMENT)

    turtle.reset()

# close the turtle window to get out of this program

这只乌龟只向前看一步 -- 他很容易让自己陷入困境，无法摆脱困境。

希望这能给您一些设计自己的海龟自动机的想法。

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