第 4.3 节练习 #5 - Allen Downey 的 "Think Python"

Question

Link 练习可在此处访问 - Case Study: Interface Design, Exercise Section 4.3

引用问题，看来我必须实现一个arc()功能：

Make a more general version of circle called arc that takes an additional parameter angle, which determines what fraction of a circle to draw. angle is in units of degrees, so when angle=360, arc should draw a complete circle.

到目前为止我写的代码：

import turtle
import math
bob = turtle.Turtle()

def polygon(t, n, length):
    for i in range(n):
        t.fd(length)
        t.lt(360/n)

def circle(t, r):
    circumference = 2 * math.pi * r
    n = int(circumference/3) + 1
    length = circumference/n
    polygon(t, n, length)

def arc(t, r, angle):
    arc_length = 2 * math.pi * r * (angle/360)
    n = (arc_length/4) + 1

arc(bob, 1000, 45)

turtle.mainloop()

我打算在 arc() 中调用 circle() 函数，就像在 circle() 中调用 polygon() 一样，但我不知道该怎么做那。除此之外，arc() 函数不会绘制任何东西，而只是显示静止不动的海龟。

我认为 Turtle 对象 bob 没有收到任何在 polygon() 中分配的移动指令。因此它所做的只是显示 Turtle 对象！

我可能是错的，这是我需要澄清的地方。我应该在 arc() 中调用 circle() 并让 Turtle 对象移动吗？有更简单的选择吗？在函数内调用函数对我来说仍然很困惑，所以更多的资源来了解它们也是很好的！

Answer 1

I'm trying to ... call the circle() function within arc() just as polygon() was called within circle()

你搞反了。问题状态：

Make a more general version of circle called arc

正如您可以使用更通用的函数 polygon() 绘制圆一样，您应该能够使用更通用的函数 arc() 绘制圆。这是一个用于思考这个问题的框架程序：

from turtle import Screen, Turtle
from math import pi

def polygon(turtle, sides, length):
    outside_angle = 360 / sides

    for _ in range(sides):
        turtle.forward(length)
        turtle.left(outside_angle)

def circle_using_polygon(turtle, radius):
    circumference = 2 * pi * radius
    sides = min(60, int(circumference / 3))
    length = circumference / sides
    polygon(turtle, sides, length)

def arc(turtle, radius, angle):
    # implement arc not by calling *circle() nor by
    # calling polygon() but rather by borrowing code
    # from both and adding one more step to reduce
    # the number of sides based on the arc angle

def circle_using_arc(turtle, radius):
    arc(turtle, radius, 360)

bob = Turtle(visible=False)

# Draw overlapping circles three different ways:

bob.color("green")
circle_using_polygon(bob, 100)

for color in ['cyan', 'magenta', 'yellow', 'black']:
    bob.color(color)
    arc(bob, 100, 90)

bob.color("blue")
circle_using_arc(bob, 100)

screen = Screen()

screen.mainloop()

Answer 2

import turtle
bob=turtle.Turtle()
import math
def arc(t,radius,angle):
    circumference = 2.0*math.pi*radius
    frac = angle/360.0
    arclength = circumference*frac
    n = 50 # pick a number
    len = arclength/n;
    turnang = angle/n
    for i in range(n):
        t.fd(len)
        t.lt(turnang)
arc(bob, 130,360)
turtle.done()

Answer 3

import tkinter
import swampy
from swampy.TurtleWorld import *

def polygon(n, t, length, angle):
    print(t)
    k= angle/360
    for i in range(0,int(n*k)):
        fd(t, length)
        p= 360
        lt(t,p/n)
        t.delay
world = TurtleWorld()
bob = Turtle()
#def circle(r):
    #l1= 2*3.14*r
    #l= l1/60
    #polygon(30, bob, l)

polygon(60, bob, 10, 180)

第 4.3 节练习 #5 - Allen Downey 的 "Think Python"

Section 4.3 Exercise #5 - "Think Python" by Allen Downey

python

function

turtle-graphics