中国大学 MOOC 课程 《Python 语言程序设计》第五周绘制树

中国大学 MOOC 课程 《Python 语言程序设计》第五周绘制树

# drawtree.py

from turtle import Turtle, mainloop

def tree(plist, l, a, f):
    """ plist is list of pens
    l is length of branch
    a is half of the angle between 2 branches
    f is factor by which branch is shortened
    from level to level."""
    if l>5:   #与之前的基例不同，这次递归，采用l长度与5的比较来结束递归。
        lst = []
        for p in plist:
            p.forward(l)#沿着当前的方向画画Move the turtle forward