php array - search for random key where value is over 0

Question

I have a php array that's made up of random numbers from 0-100.

I'm trying to figure out the cleanest and simplest method of picking a random key from that array that is greater than zero. Ultimately I'm looping through the array, subtracting a value from random keys each loop

Pseudo code:

$num_array = array(100,50,60,40,0,30,0,20);

for ($x = 0; $x < 100; $x++) {
    $rnd = RANDOM $num_array KEY WHERE > 0  
    $num_array[$rnd] = $num_array[$rnd] - 10;
}

Any suggestions on how to handle this?

EDIT: Once the loop is over I still want my array to contain 0's (originals, and any new ones after subtraction), and all the key positions need to be intact as before

Why not filter the zeroes out of the array before picking a random one? — trincot
– trincot, Commented Jul 22, 2017 at 11:35

JYoThI · Accepted Answer · 2017-07-22 11:55:53Z

2

1st : simple apply array_filter it will filter zeros from array

2nd : Apply array_rand function

<?php

$nums = [70, 100, 40, 30, 0, 45, 10];

$new_nums = array_filter($nums);

$key = array_rand($new_nums , 1);

echo $new_nums [$key];

?>

edited Jul 22, 2017 at 11:55

answered Jul 22, 2017 at 11:51

JYoThI

12.1k1 gold badge13 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user1022585 Over a year ago

Thanks, once the loop is over I still want my array to contain 0's and all the key positions intact as original, will this do that?

JYoThI Over a year ago

if you want keep the original array means just change the varibale name . check my updated answer . @user1022585

trincot · Accepted Answer · 2017-07-22 11:55:20Z

1

I would suggest to first remove the zeroes, and only then pick a random value:

$nums = [70, 100, 40, 30, 0, 45, 10];
$temp = array_values(array_filter($nums));
$random = $temp[mt_rand(0, count($temp) - 1)];

NB: random value is selected according to user comment on the PHP documentation page.

edited Jul 22, 2017 at 11:55

answered Jul 22, 2017 at 11:45

trincot

357k38 gold badges282 silver badges338 bronze badges

Comments

Nana Partykar · Accepted Answer · 2017-07-22 11:45:03Z

0

First you need to build an array which doesn't contain zeroes.

pos_nums=array();
 foreach ($nums as $num) {
  if ($num > 0) $pos_nums[] = $num;
}

PHP has the array_rand function documented here.

If you call

$pos_rand_keys = array_rand($pos_nums, 1);

then $pos_rand_keys[0] will be a random value.

edited Jul 22, 2017 at 11:45

Nana Partykar

10.5k10 gold badges50 silver badges79 bronze badges

answered Jul 22, 2017 at 11:35

Scott C Wilson

19.7k11 gold badges64 silver badges88 bronze badges

2 Comments

Jeff Over a year ago

wouldn't it be easier to put the array_rand into a loop and break if not 0?

Scott C Wilson Over a year ago

If you have to "keep trying" to pick a random value, the randomness is reduced. It's better to preprocess the array so you have a good data set, then make a random choice once.

Collectives™ on Stack Overflow

php array - search for random key where value is over 0

3 Answers 3

2 Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related