嘲諷北宜區間測速

Beiyi.py

'''
WARNING: This model does NOT reflect the situation of the real world, and
    I(the author) do NOT like to decide which policy the government should
    implement based on accidents data.
'''

import sys
import random

if not sys.version_info.major == 3 and sys.version_info.minor >= 7:
    print("Python 3.7 or higher is required.")
    sys.exit(1)


class Vehicle:
    def __init__(self, expected_speed_factor, angriness_factor):
        self.expected_speed_factor = expected_speed_factor
        self.angriness_factor = angriness_factor


class TrafficFlow:
    def __init__(self, speed_mu, speed_sigma, angriness_mu, angriness_sigma):
        self.speed_mu = speed_mu
        self.speed_sigma = speed_sigma
        self.angriness_mu = angriness_mu
        self.angriness_sigma = angriness_sigma

    def generate(self, amount):
        for _ in range(amount):
            free_speed = random.normalvariate(self.speed_mu, self.speed_sigma)
            free_speed = 0 if free_speed < 0 else free_speed
            angriness = random.normalvariate(self.angriness_mu,
                                             self.angriness_sigma)
            angriness = 0 if angriness < 0 else angriness
            yield Vehicle(free_speed, angriness)
        return


class SimplifiedAccidentModel:
    def __init__(self, traffic_flow, speed_limit):
        self.traffic_flow = traffic_flow
        self.speed_limit = speed_limit

    def run(self, amount):
        crash_probability = 0.1
        magic_number = 0.001
        crashed_amount = 0
        for vehicle in self.traffic_flow.generate(amount):
            delta_speed = vehicle.expected_speed_factor - self.speed_limit
            delta_speed = 0 if delta_speed < 0 else delta_speed
            danger_probability = delta_speed * vehicle.angriness_factor * magic_number
            if random.random() < danger_probability * crash_probability:
                crashed_amount += 1

        return crashed_amount / amount


if __name__ == '__main__':
    FREE_SPEED_MU = 60
    FREE_SPEED_SIGMA = 10
    ANGRINESS_MU = 3
    ANGRINESS_SIGMA = 1

    traffic_flow = TrafficFlow(FREE_SPEED_MU, FREE_SPEED_SIGMA, ANGRINESS_MU,
                               ANGRINESS_SIGMA)
    model40 = SimplifiedAccidentModel(traffic_flow, 40)
    result = model40.run(10**5)
    print(
        f'There are {result * 100:.2f}% of vehicles crashed under the limit of 40 kph.'
    )
    model60 = SimplifiedAccidentModel(traffic_flow, 60)
    result = model60.run(10**5)
    print(
        f'There are {result * 100:.2f}% of vehicles crashed under the limit of 60 kph.'
    )