在PHP中按重量生成随机结果? [英] Generating random results by weight in PHP?

问题描述

我知道如何在PHP中生成一个随机数，但是可以说我想要一个1-10之间的随机数，但是我想要的是3,4,5，然后是8,9,10.这怎么可能?我会发布我尝试过的内容，但老实说，我什至不知道从哪里开始.

I know how to generate a random number in PHP but lets say I want a random number between 1-10 but I want more 3,4,5's then 8,9,10's. How is this possible? I would post what I have tried but honestly, I don't even know where to start.

推荐答案

基于@Allain的 answer /链接，我在PHP中设计了此快速功能.如果要使用非整数加权，则必须对其进行修改.

Based on @Allain's answer/link, I worked up this quick function in PHP. You will have to modify it if you want to use non-integer weighting.

  /**
   * getRandomWeightedElement()
   * Utility function for getting random values with weighting.
   * Pass in an associative array, such as array('A'=>5, 'B'=>45, 'C'=>50)
   * An array like this means that "A" has a 5% chance of being selected, "B" 45%, and "C" 50%.
   * The return value is the array key, A, B, or C in this case.  Note that the values assigned
   * do not have to be percentages.  The values are simply relative to each other.  If one value
   * weight was 2, and the other weight of 1, the value with the weight of 2 has about a 66%
   * chance of being selected.  Also note that weights should be integers.
   * 
   * @param array $weightedValues
   */
  function getRandomWeightedElement(array $weightedValues) {
    $rand = mt_rand(1, (int) array_sum($weightedValues));

    foreach ($weightedValues as $key => $value) {
      $rand -= $value;
      if ($rand <= 0) {
        return $key;
      }
    }
  }

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