the-code-learning-from-Think-Python/polygon.py at master · zaiyangliu/the-code-learning-from-Think-Python · GitHub

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import math

import turtle


def square(t, length):


    for i in range(4):

        t.fd(length)

        t.lt(90)


def polyline(t, n, length, angle):


    for i in range(n):

        t.fd(length)

        t.lt(angle)


def polygon(t, n, length):


    angle = 360.0/n

    polyline(t, n, length, angle)


def arc(t, r, angle):


    arc_length = 2 * math.pi * r * abs(angle) / 360

    n = int(arc_length / 4) + 3

    step_length = arc_length / n

    step_angle = float(angle) / n


    t.lt(step_angle/2)

    polyline(t, n, step_length, step_angle)

    t.rt(step_angle/2)


def circle(t, r):


    arc(t, r, 360)


if __name__ == '__main__':

    bob = turtle.Turtle()


    radius = 100

    bob.pu()

    bob.fd(radius)

    bob.lt(90)

    bob.pd()

    circle(bob, radius)


    # wait for the user to close the window

    turtle.mainloop()