php - 在 PHP 中按权重生成随机结果？

Question

我知道如何在 PHP 中生成随机数，但可以说我想要一个介于 1-10 之间的随机数，但我想要更多的 3、4、5 和 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。

Answer 1

基于@Alllain 的answer/link ，我在 PHP 中编写了这个快速函数。如果要使用非整数加权，则必须对其进行修改。

  /**
   * 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;
      }
    }
  }