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我在 Python 中的 CS 项目遇到问题，每当我认为我即将解决问题时。

win = GraphWin("Exercise 8 Page 119", 400,400)
for i in range(1):
    p1 = win.getMouse()
    p1.draw(win)
    p1.setFill("black")
    p2 = win.getMouse()
    p2.draw(win)
    p2.setFill("black")
    line = Line(Point(p1.getX(),p1.getY()), Point(p2.getX(), p2.getY()))
    line.draw(win)
   
    # midpoint
    midpoint = line.getCenter()
    midpoint.draw(win)
    midpoint.setFill("cyan")


    import math
    # midpoint math
    yMid = p2.getY()+p1.getY()/2
    xMid = p2.getX()+p1.getX()/2
   # midpoint text
    midpointLabel = Text(Point(xMid+0.5, yMid+0.5), "midpoint is: " + "(" + str(xMid) + "," + str(yMid) + ")")
    midpointLabel.draw(win)

每当我测试它时，中点就会随机出现在某个地方，或者我根本看不到它。我似乎无法每次都将坐标靠近实际中点。这些是老师的原话“这个程序将标记中点，稍微偏离线中点的实际位置。”

请帮我！谢谢！

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1 回答 1

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我会说这个问题是一个简单的数学错误：

yMid = p2.getY()+p1.getY()/2
xMid = p2.getX()+p1.getX()/2

应该是：

yMid = (p2.getY() + p1.getY()) / 2
xMid = (p2.getX() + p1.getX()) / 2

完整代码：

from graphics import *

win = GraphWin("Exercise 8 Page 119", 400, 400)

p1 = win.getMouse()
p1.setFill("black")
p1.draw(win)

p2 = win.getMouse()
p2.setFill("black")
p2.draw(win)

line = Line(p1, p2)
line.draw(win)

# midpoint
midpoint = line.getCenter()
midpoint.setFill("cyan")
midpoint.draw(win)

# midpoint math
yMid = (p2.getY() + p1.getY()) / 2
xMid = (p2.getX() + p1.getX()) / 2
# midpoint text
midpointLabel = Text(Point(xMid + 0.5, yMid + 0.5), "midpoint is: ({}, {})".format(xMid, yMid))
midpointLabel.draw(win)

win.getMouse()
win.close()
于 2018-05-14T06:10:54.140 回答