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random_walk.py
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random_walk.py
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from random import choice
class RandomWalk:
"""
A class that generates random walks, which is
a simplified model of physical Brownian motion
that models things like a pollen grain moving across
water or the molecular motion within a water drop
"""
def __init__(self, num_points=5000):
"""Initialize the walk's attributes"""
self.num_points = num_points
# Start the walk at (0, 0)
self.x_values = [0]
self.y_values = [0]
def fill_walk(self):
"""Calculate all the points in the walk"""
# Keep taking steps until the walk reaches the desired length
while len(self.x_values) < self.num_points:
# Decide which direction to go and how far this way
x_step = self._get_step()
y_step = self._get_step()
# Reject moves that go nowehere
if x_step == 0 and y_step == 0:
continue
# Calculate and save the new position
x = self.x_values[-1] + x_step
y = self.y_values[-1] + y_step
self.x_values.append(x)
self.y_values.append(y)
def _get_step(self):
direction = choice([1, -1])
distance = choice([0, 1, 2, 3, 4, 5])
return direction * distance