'''

sierpinski.py

Draw Sierpinski Triangle

'''

import random

import matplotlib.pyplot as plt

def transformation_1(p):

x = p[0]

y = p[1]

x1 = 0.5*x

y1 = 0.5*y

return x1, y1

def transformation_2(p):

x = p[0]

y = p[1]

x1 = 0.5*x + 0.5

y1 = 0.5*y + 0.5

return x1, y1

def transformation_3(p):

x = p[0]

y = p[1]

x1 = 0.5*x + 1

y1 = 0.5*y

return x1, y1

def get_index(probability):

r = random.random()

c_probability = 0

sum_probability = []

for p in probability:

c_probability += p

sum_probability.append(c_probability)

for item, sp in enumerate(sum_probability):

if r <= sp:

return item

return len(probability)-1

def transform(p):

# list of transformation functions

transformations = [transformation_1, transformation_2, transformation_3]

probability = [1/3, 1/3, 1/3]

# pick a random transformation function and call it

tindex = get_index(probability)

t = transformations[tindex]

x, y = t(p)

return x, y

def draw_sierpinski(n):

# We start with (0, 0)

x = [0]

y = [0]

x1, y1 = 0, 0

for i in range(n):

x1, y1 = transform((x1, y1))

x.append(x1)

y.append(y1)

return x, y

if __name__ == '__main__':

n = int(input('Enter the desired number of points'

'in the Sierpinski Triangle: '))

x, y = draw_sierpinski(n)

# Plot the points

plt.plot(x, y, 'o')

plt.title('Sierpinski with {0} points'.format(n))

plt.show()