Print out a fractal tree

frascii

#!/usr/bin/env python
from math import *
import sys
 
# draw line from x,y of length s at angle theta, spawn growth of length s*r,  theta+/-q unless n==0
def grow(x, y, theta, s, q, r, n):
    ret = [(x,y,theta,s)]
    n = n-1
    if n>0:
        x2 = x + s*cos(theta)
        y2 = y + s*sin(theta)
        ret.extend(grow(x2,y2,theta+q,s*r,q,r,n))
        ret.extend(grow(x2,y2,theta-q,s*r,q,r,n))
    return ret

def signum(x): return (x>0)-(x<0)

def stroke(dx,dy) :
    return (('\\', '|', '/'),
            ('-',  '*', '-'),
            ('/',  '|', '\\'))[dy+1][1-dx]


def draw(p):
    (x,y,theta,s) = p
    (x,y) = (int(x+0.5),int(y+0.5))
    ret = [(x,y,'*')] # point at x,y
    dx = signum(int(10*cos(theta)+0.5))
    dy = signum(int(10*sin(theta)+0.5))
    ds = sqrt(dx*dx + dy*dy)
    sym = stroke(dx,dy)
    while s>ds:
        s = s - ds
        x = x+dx
        y = y+dy
        ret.append((x,y,sym))
    return ret

if __name__ == "__main__":
    q = pi/4.
    r = 0.5
    n = 8
    t = pi/2.
    s = 2. ** n
    ps = grow(0,0,t,s,q,r,n)
    #print ps
    ss = []
    for p in ps:
        ss.extend(draw(p))
    #print ss
    xmin = min([p[0] for p in ss])-1
    ymax = max([p[1] for p in ss])
    # sort points descending in y, ascending in x
    cmp=lambda p1,p2: signum(signum(p1[0]-p2[0]) - 10*signum(p1[1]-p2[1]))
    ss.sort(cmp=cmp)
    #print ss
    lastx = xmin
    lasty = ymax
    for (x,y,c) in ss:
        if x==lastx and y==lasty: continue
        if y<lasty:
            lasty=y
            lastx=xmin
            sys.stdout.write("\n")
        sys.stdout.write(" "*(x-lastx-1) + c)
        lastx=x
    sys.stdout.write("\n")