random_walk.py

import random

"""def random_walk(n):
    x = 0
    y = 0
    for i in range(n):
        step = random.choice(['N', 'S', 'E', 'W'])
        if step == 'N':
            y += 1
        elif step == 'S':
            y -= 1
        elif step == 'E':
            x += 1
        else:
            x -= 1
    return (x, y)



for i in range(25):
    walk = random_walk(10)
    print(walk, "Distance from home = ", abs(walk[0]) + abs(walk[0]))"""


def random_walk_2(n):
    x, y = 0, 0
    for i in range(n):
        (dx, dy) = random.choice([(0, 1), (0, -1), (1, 0), (-1, 0)])
        x += dx
        y += dy
    return (x, y)


number_of_walks = 15000

for walk_length in range(1, 31):
    no_transport = 0
    for i in range(number_of_walks):
        (x, y) = random_walk_2(walk_length)
        distance = abs(x) + abs(y)
        if distance <= 4:
            no_transport += 1
    no_transport_percentage = float(no_transport) / number_of_walks
    print(
        "Walk size = ",
        walk_length,
        " / % of no trnasport = ",
        100 * no_transport_percentage,
    )