Nothing fancy, but I tried one of my first exercises from my first year of computer science. Drawing a Pythogoras Tree recursively. Back then we used Modula-2. The ironic part is that Modula-2 had no drawing functionality whatsoever, so we had to dump every calculated vector in a format that would be read in by some other software to visualise it.

Now in Python:

# Pythagoras # Draws a Pythagoras Tree of n depth import math import turtle # initialize - create t object and sets it in starting position t = turtle.Pen() t.penup() t.left(90) t.back(200) t.pendown() def tree(base, n): if n == 0: return else: # draw a tree new_base = math.sqrt((base*base)/2) t.forward(base) left_branch(new_base, n-1) t.right(90) t.forward(base) right_branch(new_base, n-1) t.right(90) t.forward(base) t.right(90) t.forward(base) t.right(90) return def left_branch(base, n): # sets the turtle in the right angle and calls tree() if n == 0: return else: t.left(45) tree(base, n) t.right(45) return def right_branch(base, n): # sets the turtle in right position and angle and calls tree() if n == 0: return else: t.left(135) t.forward(base) t.right(90) tree(base, n) t.right(90) t.forward(base) t.left(45) tree(100,10)

However much I like recursive functions for their elegance (and I do admit there are much better examples of elegance than my Pythagoras Tree), I do not care much for this recursive tree as it is drawn on the screen. You can see the tree develop itself in a n-depth from left to right manner. Which means until the first call of tree() finishes the tree has no complete trunk to stand on.

I think it would be better to have a tree object with a grow method so that everytime tree.grow() is called the tree grows a little new tree from each existing branch. I don’t know how to do that yet. But when I do I’ll post it.

Here is the complete tree with depth n = 10.