Sierpinski triangle script for plot.ly, based on their Lindenmayer System demo

sierpinski.py

# Python 2.7.3 (default, Apr 20 2012, 23:04:22) [GCC 4.6.3]
# Use plot() to plot lists or arrays
# Use print to show results in the command line history

from numpy import sin, cos, pi

def f(s,itr):
	xo=0
	yo=0
	a=0
	b=pi/3	
	d=10
	for i in xrange(itr):
		ns=''
		for mv in s:
			if mv=='A':
				ns+='B-A-B'
			elif mv=='B':
				ns+='A+B+A'
			else:
				ns+=mv
		s=ns
	print s
	s=list(s)
	print len(s)
	mvs=[]
	xa=[]
	ya=[]
	for mv in s:
		if mv=='A' or mv=='B':
			x=xo+d*cos(a)		
			y=yo+d*sin(a)
			xa.append(x)
			ya.append(y)			
			xo=x
			yo=y
		elif mv=='+': a+=b
		elif mv=='-': a-=b
		elif mv=='[' and len(mvs)!=0:
			x,y=mvs.pop()
			xo=x
			yo=y
		elif mv==']':
			mvs.append((xo,yo))			
	plot(xa,ya,{'color':'black'})			

#s='F[-F]F[+F][F]'
s='A'

f(s,10)