I have below array
$a = [
'c1' => '10',
'c2' => '20',
'c3' => '10.50',
'c4' => '19.99'
'c5' => '19',
'c6' => '19',
'c7' => '1.51',
];
c1, c2, c3, c4,... is Value we need on basis of probability 10, 20, 10.50, 19.99,... .
Probability total is going to be 100%
So may be need to use rand() or mt_rand() function, so each time on basis of probability it gives random value from array.
Output can be c2 at 1st time, second time c4, third time may be c2 again
How to achieve this?
you can use rand() along with array_values()
$rand = rand (0,(count($a)-1));
echo array_values($a)[$rand];
Output: https://3v4l.org/nTPaH AND https://3v4l.org/SSDRR
Note:- You can use mt_rand() instead of rand() as well.
rand() or mt_rand() generate a random number between given numbers,
For array there are some inbuilt function array_rand() and shuffle()
<?php
// array_rand
$input = array("Some", "Many", "More", "A Lot", "All");
$rand_key = array_rand($input);
echo $input[ $rand_key ] . "\n";
.
<?php
// shuffle
$input = array("Some", "Many", "More", "A Lot", "All");
shuffle($input);
echo $input[ 0 ];
You can read more here:
https://www.php.net/manual/en/function.array-rand.php
https://www.php.net/manual/en/function.shuffle.php
Example:
array_rand - https://paiza.io/projects/e9Mo7QCkYqY37nvViWwG0A?language=php
shuffle - https://paiza.io/projects/xVs7O8-tu07JzNQQL0Gu4Q
May be you need this,
I had the same question, yet the checked was not working for my needs: I was searching for a function that rolls a dice on (any) elements in an array, based on their given probabilities. Thats what I came up with:
/**
* Dices a value from a given list with percentages.
*
* Input be like
* [
* 0 => 10.5,
* 1 => 9.2,
* '2.4' => 30,
* 'foo' => 50.3,
* ]
*
* If sum of $probabilities don't add up to 100, 100 is used to dice against and will maybe hit the fallback.
* If sum of $probabilities is more than 100, all given $probabilities will be spread accordingly.
*
* @param array $probabilities
* @param mixed $fallback
* @return mixed
*/
public static function diceOnArray(array $probabilities, mixed $fallback = null): mixed
{
$sum = max(100, array_sum($probabilities));
$fallback = $fallback ?: array_key_first($probabilities);
$random = rand(0, $sum);
foreach ($probabilities as $key => $probability) {
if ($random > $probability) {
$random -= $probability;
continue;
}
return $key;
}
// hit nothing from the list, use fallback
return $fallback;
}
I added the fallback functionality, because I often have collections not summing um to 100 (like 10%, 20% thats it) and therefore I just put $array[0] as the fallback into the function which in a way adds up the first value to what's left to 100%.
Cheers andi