使用turtle 画一些图

到处搜罗了一些turtle 的画得图，有的还挺不错的。
多数出于此：http://michael0x2a.com/blog/turtle-examples

def draw_square():
    silly=turtle.Turtle()
    for i in range(4):
        silly.forward(50)
        silly.right(90)
    turtle.done()

def draw_star():
    star=turtle.Turtle()
    for i in range(5):
        star.forward(50)
        star.right(144)
    turtle.done()

def draw_spiral_star():
    spiral=turtle.Turtle()
    for i in range(20):
        spiral.forward(i*20)
        spiral.right(144)
    turtle.done()

def draw_titled_square():
    square=turtle.Turtle()
    for k in range(3):
        square.home()
        square.left(k*10+20)
        for i in range(4):
            square.forward(100)
            square.left(90)
    turtle.done()

def draw_hexagon():
    polygon=turtle.Turtle()
    num_sides=6
    side_length=100
    angle=360.0/num_sides
    for i in range(num_sides):
        polygon.forward(side_length)
        polygon.right(angle)
    turtle.done()

def draw_points():
    seurat=turtle.Turtle()
    dot_distance=20
    width=5
    height=7
    seurat.penup()

    for y in range(height):
        for i in range(width):
            seurat.dot()
            seurat.forward(dot_distance)
        seurat.backward(dot_distance * width)
        seurat.right(90)
        seurat.forward(dot_distance)
        seurat.left(90)
    turtle.done()

def draw_ninja():
    ninja=turtle.Turtle()
    ninja.speed(10)

    for i in range(180):
        ninja.forward(100)
        ninja.right(30)
        ninja.forward(20)
        ninja.left(60)
        ninja.forward(50)
        ninja.right(30)

        ninja.penup()
        ninja.setposition(0,0)
        ninja.pendown()

        ninja.right(2)

    turtle.done()

#the below 2 function draws a lotus
def petal(radius,steps):
    turtle.circle(radius,90,steps)
    turtle.left(90)
    turtle.circle(radius,90,steps)

def draw_lotus():
    turtle.hideturtle()
    turtle.speed(1)
    turtle.tracer(False)
    num_petals=8
    steps=8
    radius=100
    for i in range(num_petals):
        turtle.setheading(0)
        turtle.right(360*i//num_petals)
        petal(radius,steps)

    turtle.tracer(True)
    turtle.done()