Java：具有非均匀分布的随机整数

问题描述

如何在Java中创建一个随机整数 n ，在 1 和 k之间带有线性递减分布，即 1 最有可能， 2 少于可能， 3 不太可能，......， k 最不可能，并且概率线性下降，如下所示：

How can I create a random integer n in Java, between 1 and k with a "linear descending distribution", i.e. 1 is most likely, 2 is less likely, 3 less likely, ..., k least likely, and the probabilities descend linearly, like this:

我知道已经有关于这个主题的线程问题，我为制作新主题而道歉，但我似乎无法从他们那里创造我需要的东西。我知道使用 import java.util。*; ，代码

I know that there are dosens of threads on this topic already, and I apologize for making a new one, but I can't seem to be able to create what I need from them. I know that using import java.util.*;, the code

Random r=new Random();
int n=r.nextInt(k)+1;

在 1 和 k ，统一分配。

GENERALIZATION：创建任意分布整数的任何提示，即 f（n）=某个函数， P（n）= f（n）/（f（1）+ ... + f（k））），也将不胜感激，例如：
。

GENERALIZATION: Any hints for creating an arbitrarily distributed integer, i.e. f(n)=some function, P(n)=f(n)/(f(1)+...+f(k))), would also be appreciated, for example:.

推荐答案

这应该可以满足您的需求：

This should give you what you need:

public static int getLinnearRandomNumber(int maxSize){
    //Get a linearly multiplied random number
    int randomMultiplier = maxSize * (maxSize + 1) / 2;
    Random r=new Random();
    int randomInt = r.nextInt(randomMultiplier);

    //Linearly iterate through the possible values to find the correct one
    int linearRandomNumber = 0;
    for(int i=maxSize; randomInt >= 0; i--){
        randomInt -= i;
        linearRandomNumber++;
    }

    return linearRandomNumber;
}

此外，这里是POSITIVE函数的一般解决方案（否定函数不确实有意义）从start index到stopIndex的范围：

Also, here is a general solution for POSITIVE functions (negative functions don't really make sense) along the range from start index to stopIndex:

public static int getYourPositiveFunctionRandomNumber(int startIndex, int stopIndex) {
    //Generate a random number whose value ranges from 0.0 to the sum of the values of yourFunction for all the possible integer return values from startIndex to stopIndex.
    double randomMultiplier = 0;
    for (int i = startIndex; i <= stopIndex; i++) {
        randomMultiplier += yourFunction(i);//yourFunction(startIndex) + yourFunction(startIndex + 1) + .. yourFunction(stopIndex -1) + yourFunction(stopIndex)
    }
    Random r = new Random();
    double randomDouble = r.nextDouble() * randomMultiplier;

    //For each possible integer return value, subtract yourFunction value for that possible return value till you get below 0.  Once you get below 0, return the current value.
    int yourFunctionRandomNumber = startIndex;
    randomDouble = randomDouble - yourFunction(yourFunctionRandomNumber);
    while (randomDouble >= 0) {
        yourFunctionRandomNumber++;
        randomDouble = randomDouble - yourFunction(yourFunctionRandomNumber);
    }

    return yourFunctionRandomNumber;
}

注意：对于可能返回负值的函数，可以采用一种方法该函数的绝对值，并将其应用于每个yourFunction调用的上述解决方案。

Note: For functions that may return negative values, one method could be to take the absolute value of that function and apply it to the above solution for each yourFunction call.

这篇关于Java：具有非均匀分布的随机整数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！