モンティホール問題シミューレション

montyhall.py

#!/usr/bin/env python3
# coding: utf-8

import numpy as np


NUM = 100000 # 試行回数
DOORS = np.array([1, 2, 3]) # ドア 


# 変更しない場合
succeeded = 0
for i in range(NUM):
    car = np.random.choice(DOORS)
    selected = np.random.choice(DOORS)
    if selected == car:
        succeeded += 1
print('No change: ', str(succeeded/NUM))


# 変更した場合
succeeded = 0
for i in range(NUM):
    car = np.random.choice(DOORS)
    selected = np.random.choice(DOORS)
    goat = np.random.choice(DOORS[(DOORS != car) & (DOORS != selected)])
    selected = np.random.choice(DOORS[(DOORS != goat) & (DOORS != selected)])
    if selected == car:
        succeeded += 1
print('Change: ', str(succeeded/NUM))