Draw with different percentages

Question

Draw with different percentages

Navigation

#1 by (1 votes)

1

I have an "open boxes" system, which works as follows:

The box can have X items (amount you want) where each item will have Y% of gain, being: # or # .1% (no more decimal places)

That is: "Box one" can have 10 items, where:

0.5% chanca to be won

1% chance of being won

4% chanca to be won

4.5% chanca to be won

5% chanca to be won

15% chance of being won

20% chanca to be won

Always the sum of percentage of victory of the items will be of 100% round

Currently, I only have a simple function that takes any item from the array of items in the box:

$vencedor = $items[array_rand($items)];

And it brings me the item "drawn", what I need is that the percentage of each item is taken into account, and I'm not getting it

I tried some things, none came to the desired result

php

asked by anonymous 16.07.2018 / 04:50

1 answer

Button Bind in Tkinter.ttk TreeView in another Class How to count how many fields are empty in the mysql table

score 1 · Accepted Answer

The solution proposed by @bfavaretto in the comments works perfectly. Here is another suggestion if you have not been able to solve it.

I made a solution based on a range of numbers that each element can have. The higher the chance percentage, the greater the number range of each element. Based on your example, I've created the following array:

$items = array(

    "Item 1" => 0.5, // porcentagens
    "Item 2" => 1,
    "Item 3" => 4,
    "Item 4" => 4.5,
    "Item 5" => 5,
    "Item 6" => 15,
    "Item 7" => 15,
    "Item 8" => 15,
    "Item 9" => 20,
    "Item 10" => 20

);

With this, a new array is generated with the name of each element and its respective ranges through this code:

$valor = 1000; // valor do peso máximo e total dos itens
$inicio = 1;
$ultimo_valor = 0;

$array_elementos = array(); // array para sorteio

// cria o array para sorteio
foreach($items as $nome => $porcentagem){

    $val =  ($valor * $porcentagem) / 100;
    $valorFinal = $val + $inicio - 1;
    $array_elementos[$nome] = $inicio."-".$valorFinal;
    $inicio = $valorFinal + 1;

}

See how the $array_elementos array was:

Array ( 

    [Item 1] => 1-5 
    [Item 2] => 6-15 
    [Item 3] => 16-55 
    [Item 4] => 56-100 
    [Item 5] => 101-150 
    [Item 6] => 151-300 
    [Item 7] => 301-450 
    [Item 8] => 451-600 
    [Item 9] => 601-800 
    [Item 10] => 801-1000 

)

Now just draw a random number and look in the array in which element is the number. So:

// numero randômico "sorteio"
// de 1 até o valor máximo
$num_rand = rand(1, $valor);

$elemento_sorteado = "";

// procura o elemento sorteado
foreach($array_elementos as $nome => $peso){
    $valores = explode("-", $peso);
    if($num_rand >= $valores[0] && $num_rand <= $valores[1]){
        $elemento_sorteado = $nome;
        break;
    }
}

echo $elemento_sorteado;

See the code working ideone