Turtle Graphics：如何向上移动标签？

Question

我正在学习 Python 并且正在尝试编辑有以下错误的代码：

Each height label is partly covered by the top segment of its bar. Can you modify the drawBar code, moving the label up slightly but not changing the bar? Hint: The label cannot be drawn during the polygon fill sequence.

我已经尝试 def 一个新功能，但是没有用。你能找到 error/edit 吗？

def drawBar(t, height):
    """ Get turtle t to draw one bar, of height. """
    t.begin_fill()               # start filling this shape
    t.left(90)
    t.forward(height)
    t.write(str(height))
    t.right(90)
    t.forward(40)
    t.right(90)
    t.forward(height)
    t.left(90)
    t.end_fill()                 # stop filling this shape

xs = [48, 117, 200, 240, 160, 260, 220]  # here is the data
maxheight = max(xs)
numbars = len(xs)
border = 10

wn = turtle.Screen()             # Set up the window and its attributes
wn.setworldcoordinates(0-border, 0-border, 40*numbars+border, maxheight+border)
wn.bgcolor("lightgreen")

tess = turtle.Turtle()           # create tess and set some attributes
tess.color("blue")
tess.fillcolor("red")
tess.pensize(3)

for a in xs:
    drawBar(tess, a)

wn.exitonclick()

Answer 1

如果你想向上移动，那么举起笔，向前移动，写文字，向后移动，放下宠物。

t.penup()
t.forward(2)
t.write(str(height))
t.forward(-2)
t.pendown()

最小工作代码

import turtle

def drawBar(t, height):
    """ Get turtle t to draw one bar, of height. """
    t.begin_fill()               # start filling this shape
    t.left(90)
    t.forward(height)
    
    t.penup()
    t.forward(2)
    t.write(str(height))
    t.forward(-2)
    t.pendown()

    t.right(90)
    t.forward(40)
    t.right(90)
    t.forward(height)
    t.left(90)
    t.end_fill()              # stop filling this shape

xs = [48, 117, 200, 240, 160, 260, 220]  # here is the data
maxheight = max(xs)
numbars = len(xs)
border = 10

wn = turtle.Screen()             # Set up the window and its attributes
wn.setworldcoordinates(0-border, 0-border, 40*numbars+border, maxheight+border)
wn.bgcolor("lightgreen")

tess = turtle.Turtle()           # create tess and set some attributes
tess.color("blue")
tess.fillcolor("red")
tess.pensize(3)

for a in xs:
    drawBar(tess, a)

wn.exitonclick()

编辑：

如果你想向上和向右移动

t.penup()

t.forward(2)
t.right(90)
t.forward(3)

t.write(str(height))

t.forward(-3)
t.right(-90)
t.forward(-2)

t.pendown()

Answer 2

您可以通过保存海龟的状态（它的位置和航向），在绘制标签之前将它稍微向右移动一点，然后再恢复它的状态来实现。

我的意思是：

def drawBar(t, height):
    """ Get turtle t to draw one bar, of height. """
    t.begin_fill()               # start filling this shape
    t.left(90)
    t.forward(height)

    posn = t.position()          # Save position.
    heading = t.heading()        # Save heading.
    t.right(90)                  # Point to the right.
    t.forward(1)                 # Move over a little.
    t.write(height)              # Display the label.
    t.goto(posn)                 # Restore position.
    t.setheading(heading)        # Restore heading.

    t.right(90)
    t.forward(40)
    t.right(90)
    t.forward(height)
    t.left(90)
    t.end_fill()                 # stop filling this shape

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