It draws a random Gumowski-Mira Strange Attractor. (It would retry until a good one is found to display.)
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 | # Gumowski-Mira Strange Attractor
# http://en.wikipedia.org/wiki/Attractor
# FB - 201012072
import random
from PIL import Image
imgx = 800
imgy = 600
maxIt = 50000 # number of pixels to draw
# drawing area (xa < xb and ya < yb)
xa = -20.0
xb = 20.0
ya = -20.0
yb = 20.0
def f(x):
return a * x + 2.0 * (1.0 - a) * x * x / (1.0 + x * x)
def gm(x, y):
xnew = b * y + f(x)
y = -x + f(xnew)
x = xnew
return (x, y)
while True:
image = Image.new("L", (imgx, imgy)) # clear the image
a = random.random() * 1.5 - 1.0
b = random.random() * 0.1 + 0.9
x = random.random() * (xb - xa) + xa
y = random.random() * (yb - ya) + ya
pixelCtr = 0
for i in range(maxIt):
(x, y) = gm(x, y)
xi = int((imgx - 1) * (x - xa) / (xb - xa))
yi = int((imgy - 1) * (y - ya) / (yb - ya))
if xi >=0 and xi < imgx and yi >= 0 and yi < imgy:
if image.getpixel((xi, yi)) == 0:
image.putpixel((xi, yi), 255)
pixelCtr += 1
if 100 * pixelCtr / maxIt > 10: # retry until a good attractor is found
break
image.save("strange_attractor.png", "PNG")
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