import numpy as np
import matplotlib.pyplot as plt

class BrownIterator(object):
	def __init__(self, N, m):
		self._N = N
		self._max_m = m
		self._i = 0
		self._xs = None
		self._ys = None
	def __iter__(self):
		self._xs = np.zeros(self._N)
		self._ys = np.zeros(self._N)
		self._i = 0
		return self
	def __next__(self):
		self._i += 1
		if(self._i > self._max_m):
			raise StopIteration()
		if(self._i == 1):
			return self._xs, self._ys

		theta = np.random.uniform(0, np.pi * 2, self._N)

		self._xs = self._xs + np.cos(theta)
		self._ys = self._ys + np.sin(theta)
		return self._xs, self._ys

if( __name__ == "__main__"):
	data = np.array([i for i in BrownIterator(1000, 321)])
	print(data)

	p1, = plt.plot(data[20,0], data[20,1], "ro", label="t = 20")
	p2, = plt.plot(data[80,0], data[80,1], "bo", label="t = 80")
	p3, = plt.plot(data[320,0], data[320,1], "go", label="t = 320")

	plt.legend(handles=[p1, p2, p3])
	plt.show()