PHP Probabilistic algorithm function

This article mainly introduces the PHP probability algorithm function, the interest friend's reference, hoped to be helpful to everybody.

The code is as follows:

<?php/** * Probability calculation class * Can be used for sweepstakes and other */class probability{/** * probability statistics * thing = CH  ance */var $data = array ();   var $chance _count = 0;      function __construct ($initdata = Array ()) {if (!empty ($initdata)) {$this->data = $initdata;      foreach ($initdata as $d) {$this->chance_count + = $d [' num '];    }}} function AddData ($name, $chance) {$this->data[]=array (' name ' = = $name, ' num ' = $chance);  $this->chance_count + = $chance;    } function GetOne () {$index = rand (0, $this->chance_count);      foreach ($this->data as $d) {$index = $index-$d [' num '];      if ($index <=0) {return $d [' name '];  }} "return"; }}/** * Use example */$pro =new probability (), $pro->adddata (' iphone '), $pro->adddata (' Watch '); $pro->adddata ( ' $18 ', $pro->adddata (' Thank you '), $pro->adddata (' Super big ', 1); for ($i =0; $i <100; $i + +) {echo $pro- >getone (). " \ n ";} 

This is a very classical probability algorithm function:

function Get_rand ($PROARR) {   $result = ';   The total probability accuracy of the probability array   $proSum = Array_sum ($PROARR);   Probability array Loop   foreach ($proArr as $key + = $proCur) {     $randNum = Mt_rand (1, $proSum);       Extract the random number    if ($randNum <= $proCur) {       $result = $key;             The result is break      ;     } else {       $proSum-= $proCur;}   }   Unset ($PROARR);   return $result; }

Suppose: We have such an array: a prize probability 20%,b prize probability 30%,c prize probability 50%

$prize _arr =array (' A ' =>20, ' B ' =>30, ' C ' =>50);

Simulation function Execution Process:

Total probability accuracy is 20+30+50=100

First-time array loop, $procur =20

Assuming the extracted random number rand (1,100), assume that pumping to $randnum=55

If Judgment-------

If $randnum<=20, then result=a

Otherwise into the next cycle, the total probability accuracy becomes 100-20=80

Second array loop, $procur =30

Assuming the decimation of the random number rand (1,80), assume that pumping to $randnum=33

If Judgment---------

If $randnum<=30, then result=b

Otherwise into the next cycle, the total probability accuracy becomes 80-30=50

The third array loop, $prosur = 50;

Assuming the extracted random number rand (1,50), no matter how pumped, the random number will be < or = 50,

then draw result=c;

Because the sample does not change, although it is possible to extract more than one random number, the probability is constant.

Or you can do this:

  function Get_rand ($arr)  {    $pro _sum=array_sum ($arr);    $rand _num=mt_rand (1, $pro _sum);    $tmp _num=0;    foreach ($arr as $k    = + $val) {        if ($rand _num<= $val + $tmp _num)      {        $n = $k;        break;      } else      {        $tmp _num+= $val;      }    }    return $n;  }

To share with you a lottery probability algorithm

/* Classic probability algorithm, * $PROARR is a pre-set array, * Assuming array is: Array (100,200,300,400), * Start is to filter from 1,1000 this probability range of whether the first number within the probability range of his occurrence, * if not, then the probability space , that is, the value of K minus the probability space of the first number, * in this case, minus 100, that is, the second number is filtered within the 1,900 range. * This filter to the end, there will always be a number to meet the requirements. * is equivalent to go to a box to touch things, * The first is not, the second is not, the third is not, the last one must be. * This algorithm is simple and very efficient, * The key is that this algorithm has been used in our previous projects, especially the large data volume of the project is very efficient.  */function Get_rand ($PROARR) {$result = ';  The total probability accuracy of the probability array $proSum = Array_sum ($PROARR);    Probability array loop foreach ($proArr as $key + = $proCur) {$randNum = Mt_rand (1, $proSum);      if ($randNum <= $proCur) {$result = $key;    Break    } else {$proSum-= $proCur;  }} unset ($PROARR);  return $result;} /* * Awards Array * is a two-dimensional array that records all prize information for this draw, * where the ID indicates the winning level, prize represents the prize, and V indicates the probability of winning. * Note that the V must be an integer, and you can set the V of the corresponding prize to 0, meaning that the odds of the prize being pumped are 0, * the sum of V in the array (cardinality), the larger the cardinality, the more accurate the probability. * The sum of V in this example is 100, then the probability of winning the tablet corresponds to 1%, * if the sum of V is 10000, then the probability of winning is one out of 10,000. * */$prize _arr = Array (' 0 ' = = Array (' ID ' =>1, ' prize ' = ' tablet ', ' V ' =>1), ' 1 ' = = Array (' ID ' =>2, ' prize ' =&G t; ' Digital camera ', ' V ' =>5), ' 2 ' = = Array (' ID ' =>3, ' prize ' = ' = ' Speaker device ', ' V ' =>10), ' 3 ' = = Array (' ID ' =>4, ' prize ' = ' 4G ') ', ' V ' =>12), ' 4 ' = = Array (' ID ' =>5, ' prize ' = ' 10Q ', ' V ' =>22), ' 5 ' = = Array (' ID ' =>6, ' prize ' = ' = ' next time it will be able to be in oh ', ' V ' = &GT;50),); /* * Each front page request, PHP Loop Award set Array, * Get the prize ID from the Get_rand by the probability calculation function. * Save the winning prizes in the array $res[' yes ', * while the remaining non-winning information is saved in $res[' no ', * finally output JSON data to the front page. */foreach ($prize _arr as $key = + $val) {$arr [$val [' id ']] = $val [' V '];} $rid = Get_rand ($arr); Get the prize ID $res by probability [' yes '] = $prize _arr[$rid -1][' Prize '); Medium Prize unset ($prize _arr[$rid-1]); The prize is excluded from the array and the remaining awards are shuffle ($prize _arr); Scrambled array order for ($i =0; $i <count ($prize _arr); $i + +) {$PR [] = $prize _arr[$i] [' Prize '];} $res [' no '] = $PR;p rint_r ($res [' yes ']);

Summary : The above is the entire content of this article, I hope to be able to help you learn.

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