php random number within range - no repeat

Question

Haven't been able to find what I'm looking for so far, so I'm asking for help.

I have a div with a class that needs to end in a number between 1 and 8, and I need it to be a random number, without repeating...

<div class="parallax parallax_<?php echo $random_number ?>"></div>

I figured this should be pretty simple, but I'm having trouble.

Currently, I have:

<div class="parallax parallax_<?php echo rand(1, 8); ?>"></div>

which works, but produces duplicates.

EDIT

So after testing, I realized I am running into a problem. I am using this within a wordpress template. I am querying a set of 6 posts, and for each set of posts, I am including the above parallax div. So, I get a random, none repeating number for each query, but each query resets the numbers - giving me duplicates... Here is my entire code.

<?php
  $args = array(
    'post_type'        => 'post',
    'orderby'          => 'menu_order',
    'posts_per_page'   => -1,
    'order'            => 'ASC'
  );
  $posts = get_posts( $args );
?>

<?php foreach (array_chunk($posts, 6, true) as $posts) :  ?>
  <div class="parallax parallax_<?php echo rand(1, 8); ?>"></div>
  <div class="posts_container">  
    <?php foreach( $posts as $post ) : setup_postdata($post); ?>

      <div class="post">
        <div class="post__thumbnail"><a href="<?php the_permalink();?>"><?php the_post_thumbnail(); ?></a></div>
        <div class="post__title"><?php the_title(); ?></div>
      </div>

    <?php endforeach; ?> 
  </div>
<?php endforeach; ?>

___random number, without repeating___ is not strictly a randon number — RiggsFolly, Oct 05 '16 at 13:08
Possible duplicate of [Generating random numbers without repeats](http://stackoverflow.com/questions/17778723/generating-random-numbers-without-repeats) — Thamaraiselvam, Oct 05 '16 at 13:21
I think that EDIT is a big enough change to the question to warant you asking it as a new question — RiggsFolly, Oct 05 '16 at 13:48

score 5 · Answer 1 · answered Oct 05 '16 at 13:07

5

I would do a range and shuffle:

$myRange = range(1, 8);
shuffle($myRange);
return $myRange[0];

answered Oct 05 '16 at 13:07

Praveen Kumar Purushothaman

164,888
24
203
252

1

Would be better to make the array static and pop one value off of it at a time. But using shuffle() is elegant and terse. – syck Oct 05 '16 at 13:21
2

@RiggsFolly Didn't expect this from you. Just loop `$myRange`, which is what I intended. – Praveen Kumar Purushothaman Oct 05 '16 at 13:22
1

I did say that I may have misunderstood how to run in 8 times correctly – RiggsFolly Oct 05 '16 at 13:33
Wow, @RiggsFolly Were you able to understand what Thamaraiselvam spoke? That was a bullet reply to what he said in Tamil. – Praveen Kumar Purushothaman Oct 05 '16 at 13:33
Enaku enamo avan loop keyword a vachi catch panitan nu ninaikuren – Thamaraiselvam Oct 05 '16 at 13:35
2

@PraveenKumar Google translate does not make that good a job of it I am afraid, but I did guess Tamil – RiggsFolly Oct 05 '16 at 13:37
1

@RiggsFolly Google Translate is still a baby in terms of South Indian languages. – Praveen Kumar Purushothaman Oct 05 '16 at 13:38
Ok, I did a less simplistic (some may say dumb) test and I retract my ignorant earlier comment – RiggsFolly Oct 05 '16 at 13:40
@RiggsFolly Mate, you are always awesome. No doubt. `:D` Was just kidding. – Praveen Kumar Purushothaman Oct 05 '16 at 13:40
@PraveenKumar No I apologise. Its fine being a smart ass when you are right, but I was Soooo wrong it is almost painful. – RiggsFolly Oct 05 '16 at 13:41
@RiggsFolly Na... Don't worry. :D Shit happens. – Praveen Kumar Purushothaman Oct 05 '16 at 13:42

Andrej Buday · Answer 2 · 2016-10-05T13:34:26.630

4

This code prevent duplicate and fits to any other test case scenario. Shuffling is not necessary, random element is based on array_rand() function.

To pick repetitively new random key it is necessary to use code in the loop.

// Array declaration
$a=array(1,2,3,4,5,6,7,8);

// Loop
$randomKey=array_rand($a);
unset($a[$randomKey]);

// Test
echo $randomKey."<br>";
var_dump($a);

First it is defined an array of numbers which are desired. Than random key from array is picked. It is also unset from array so it will be not used again.

For repeating action $randomKey and unset() should be in loop. Echo and var_dump() function is only for testing purpose. Array size can decrease unsetting already used key or stay same length leaving unset() function from the loop.

edited Oct 05 '16 at 13:34

answered Oct 05 '16 at 13:16

Andrej Buday

559
5
14

1

This looks good but should `echo $a[$randomKey];` and move the `unset` to after you echo the number!!!!! – RiggsFolly Oct 05 '16 at 13:29
Order doesn't matter. You can do as you please, test part is only for informative purpose. – Andrej Buday Oct 05 '16 at 13:34

Ionut Necula · Answer 3 · 2016-10-05T13:42:14.117

0

You can use uniqid() function along with md5 to strengthen the results:

 md5(uniqid(rand(1, 8), true));

Or use shuffle.

$numbers = range(1, 8);
shuffle($numbers);

foreach ($numbers as $number) {
    echo "$number ";
}

edited Oct 05 '16 at 13:42

answered Oct 05 '16 at 13:07

Ionut Necula

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4
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Does not prevent duplicates. – syck Oct 05 '16 at 13:16
And uniqid() and md5() do not make the result more random. – syck Oct 05 '16 at 13:19
Maybe, but it's a start. Also in the loop he can add a counter to the end of each number to make it even more unique. Please do post a better answer. I dare you. – Ionut Necula Oct 05 '16 at 13:22

Thamaraiselvam · Answer 4 · 2016-10-05T13:23:16.167

0

I think this could help you. shuffle() here

<?php
$numbers = range(1, 8);
shuffle($numbers);
foreach ($numbers as $number) {
    echo "$number ";
}

edited Oct 05 '16 at 13:23

answered Oct 05 '16 at 13:13

Thamaraiselvam

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8
45
71

php random number within range - no repeat

4 Answers4