递归可视化—turtle海龟作图

基础作图

import turtle
t = turtle.Turtle()

#作图开始
t.forward(100)#指挥海龟作图

#作图结束
turtle.done()

#画一个正方形
t1 = turtle.Turtle()

for i in range(4):
    t1.forward(100)
    t1.right(90)

turtle.done()

#画五角星
import turtle

t2 = turtle.Turtle()

t2.pencolor('red')
t2.pensize(3)

for i in range(5):
    t2.forward(100)
    t2.right(144)

t2.hideturtle

turtle.done()

递归作图

分形树

#分形树

def tree(branch_len):
    if branch_len>5:#树干太短不画
        t4.forward(branch_len)#画树干
        t4.right(20)#右倾斜20°
        tree(branch_len-15)#递归调用，画右边的小树
        t4.left(40)#向左回40°，左倾20°
        tree(branch_len-15)
        t4.right(20)
        t4.backward(branch_len)#海龟退回原位置

t4 = turtle.Turtle()
t4.left(90)
t4.penup()
t4.backward(100)
t4.pendown()
t4.pencolor('green')
t4.pensize(2)
tree(75)#画树干长度75的二叉树
t4.hideturtle()
turtle.done()

好看的樱花~

from turtle import *
from random import *
from math import *

def tree(n,l):
    pd()#下笔
    #阴影效果
    t = cos(radians(heading()+45))/8+0.25
    pencolor(t,t,t)
    pensize(n/3)
    forward(l)#画树枝

    if n>0:
        b = random()*15+10 #右分支偏转角度
        c = random()*15+10 #左分支偏转角度
        d = l*(random()*0.25+0.7) #下一个分支的长度
        #右转一定角度,画右分支
        right(b)
        tree(n-1,d)
        #左转一定角度，画左分支
        left(b+c)
        tree(n-1,d)
        #转回来
        right(c)
    else:
        #画叶子
        right(90)
        n=cos(radians(heading()-45))/4+0.5
        pencolor(n,n*0.8,n*0.8)
        circle(3)
        left(90)
        #添加0.3倍的飘落叶子
        if(random()>0.7):
            pu()
            #飘落
            t = heading()
            an = -40 +random()*40
            setheading(an)
            dis = int(800*random()*0.5 + 400*random()*0.3 + 200*random()*0.2)
            forward(dis)
            setheading(t)
            #画叶子
            pd()
            right(90)
            n = cos(radians(heading()-45))/4+0.5
            pencolor(n*0.5+0.5,0.4+n*0.4,0.4+n*0.4)
            circle(2)
            left(90)
            pu()
            #返回
            t=heading()
            setheading(an)
            backward(dis)
            setheading(t)
    pu()
    backward(l)#退回

bgcolor(0.5,0.5,0.5)#背景色
ht()#隐藏turtle
speed(0)#速度 1-10渐进，0 最快
tracer(0,0)
pu()#抬笔
backward(100)
left(90)#左转90度
pu()#抬笔
backward(300)#后退300
tree(12,100)#递归7层
done()