Question

我已经使用以下example code在Python中实现了Mersenne Twister，虽然它确实按预期工作，但我不清楚如何将结果限制为返回到一系列整数。例如，如果我想使用这种机制来确定掷骰子的价值，我会（现在，以极其低效的方式）迭代来自MT的潜在结果，直到某些东西落入该集合内。必须有一种更节省内存的方式才能使值落在设定范围内，如1-20。

目前，该算法会返回一组随机数字，这些数字似乎不会在接近设定范围的任何地方达到峰值：

出于测试目的，我实现了当前的测试逻辑（__main__的一部分），到目前为止它只是无限运行。

#!/usr/bin/env python2
# -*- coding: utf-8 -*-
"""
Based on the pseudocode in https://en.wikipedia.org/wiki/Mersenne_Twister. Generates uniformly distributed 32-bit integers in the range [0, 232 − 1] with the MT19937 algorithm

Yaşar Arabacı <yasar11732 et gmail nokta com>
"""
# Create a length 624 list to store the state of the generator
MT = [0 for i in xrange(624)]
index = 0

# To get last 32 bits
bitmask_1 = (2 ** 32) - 1

# To get 32. bit
bitmask_2 = 2 ** 31

# To get last 31 bits
bitmask_3 = (2 ** 31) - 1

def initialize_generator(seed):
    "Initialize the generator from a seed"
    global MT
    global bitmask_1
    MT[0] = seed
    for i in xrange(1,624):
        MT[i] = ((1812433253 * MT[i-1]) ^ ((MT[i-1] >> 30) + i)) & bitmask_1


def extract_number():
    """
    Extract a tempered pseudorandom number based on the index-th value,
    calling generate_numbers() every 624 numbers
    """
    global index
    global MT
    if index == 0:
        generate_numbers()
    y = MT[index]
    y ^= y >> 11
    y ^= (y << 7) & 2636928640
    y ^= (y << 15) & 4022730752
    y ^= y >> 18

    index = (index + 1) % 624
    return y

def generate_numbers():
    "Generate an array of 624 untempered numbers"
    global MT
    for i in xrange(624):
        y = (MT[i] & bitmask_2) + (MT[(i + 1 ) % 624] & bitmask_3)
        MT[i] = MT[(i + 397) % 624] ^ (y >> 1)
        if y % 2 != 0:
            MT[i] ^= 2567483615

if __name__ == "__main__":
    from datetime import datetime
    now = datetime.now()
    solved = False
    initialize_generator(now.microsecond)
    #for i in xrange(10):
    #    "Print 10 random numbers as an example"
    while(solved != True):
        generated_number = extract_number()
        while(generated_number <= 20 and generated_number >= 1):
            print generated_number
            solved = True

有关如何实施的任何建议？它似乎甚至没有机会下降到预定义集合中的数字。

如何根据Mersenne Twister返回值从两个数字中提取随机值

0 个答案: