php select multiple random keys from array

Question

I have been trying to select random items from an array without repeating the same item.

Sample Array

$images=array();
$images[]=array('img'=>'bands.jpg','cat'=>'bands.php');
$images[]=array('img'=>'cake.jpg','cat'=>'cakes.php');
$images[]=array('img'=>'catering.jpg','cat'=>'catering.php');
$images[]=array('img'=>'dj.jpg','cat'=>'djs.php');
$images[]=array('img'=>'dress.jpg','cat'=>'dress_attire.php');
$images[]=array('img'=>'limos.jpg','cat'=>'limos_transportaion.php');
$images[]=array('img'=>'photography.jpg','cat'=>'photography.php');
$images[]=array('img'=>'venues.jpg','cat'=>'venues.php');
$images[]=array('img'=>'wedding_planer.jpg','cat'=>'planning.php');

I have tried the following but for some reason it will not work correctly. It is only collecting the first items in the array to the count rendered. // $adDisplay is a number between 1-9

$rand = array_rand($images, $adDisplay);
foreach($rand as $key => $value){
    echo'<a href="'.$images[$key]['cat'].'"><img src="img/banners/'.$images[$key]['img'].'" border="0" alt="" /></a>';
}

$value, not $key. $images[$value]['cat']

goat
– goat

2012-12-21 22:13:30 +00:00
Commented Dec 21, 2012 at 22:13 — goat
– goat, Commented Dec 21, 2012 at 22:13

Nick · Accepted Answer · 2012-12-21 22:26:32Z

Many ways of doing this, I'd probably shuffle and then slice the array:

$images = array();
$images[]=array('img'=>'bands.jpg','cat'=>'bands.php');
$images[]=array('img'=>'cake.jpg','cat'=>'cakes.php');
$images[]=array('img'=>'catering.jpg','cat'=>'catering.php');
$images[]=array('img'=>'dj.jpg','cat'=>'djs.php');
$images[]=array('img'=>'dress.jpg','cat'=>'dress_attire.php');
$images[]=array('img'=>'limos.jpg','cat'=>'limos_transportaion.php');
$images[]=array('img'=>'photography.jpg','cat'=>'photography.php');
$images[]=array('img'=>'venues.jpg','cat'=>'venues.php');
$images[]=array('img'=>'wedding_planer.jpg','cat'=>'planning.php');

shuffle($images);

$adDisplay = 5;

foreach( array_slice($images,0,$adDisplay) as $image){
    echo '<a href="' . htmlspecialchars($image['cat']) . '">'
         . '<img src="img/banners/'
         . htmlspecialchars($image['img']) . ' border="0" alt="" />'
         . '</a>';
}

Explosion Pills · Accepted Answer · 2012-12-21 22:14:19Z

0

array_rand returns the random keys as values. You actually want to use $images[$value]['cat']. Also keep in mind that array_rand does not return an array if one item is requested; you must handle that specially.

answered Dec 21, 2012 at 22:14

Explosion Pills

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Comments

Kevin Kenyon · Accepted Answer · 2012-12-21 22:15:55Z

0

The key will be the index, value will be the random variable, thus use value instead of key as the index into your images array. Cheers.

answered Dec 21, 2012 at 22:15

Kevin Kenyon

435 bronze badges

Comments

Emil Aspman · Accepted Answer · 2012-12-21 22:40:08Z

0

Use shuffle if you want your array in random order:

shuffle($images);

foreach($images as $img) {
    echo($img['cat']);
}

Or use array_rand to get a random key:

$key = array_rand($images);

echo($images[$key]['cat']);

answered Dec 21, 2012 at 22:40

Emil Aspman

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Comments

Alan · Accepted Answer · 2013-03-31 10:38:35Z

0

You can simply use array_rand and store latest key on variable or somewhere

If random_key == last_used_key then Random_key+1

Not harder than that :-)

answered Mar 31, 2013 at 10:38

Alan

1

Comments

Eligos · Accepted Answer · 2013-11-04 15:44:33Z

Alternative suggestion:

$images = array();
$images[]=array('img'=>'bands.jpg','cat'=>'bands.php');
$images[]=array('img'=>'cake.jpg','cat'=>'cakes.php');
$images[]=array('img'=>'catering.jpg','cat'=>'catering.php');
$images[]=array('img'=>'dj.jpg','cat'=>'djs.php');
$images[]=array('img'=>'dress.jpg','cat'=>'dress_attire.php');
$images[]=array('img'=>'limos.jpg','cat'=>'limos_transportaion.php');
$images[]=array('img'=>'photography.jpg','cat'=>'photography.php');
$images[]=array('img'=>'venues.jpg','cat'=>'venues.php');
$images[]=array('img'=>'wedding_planer.jpg','cat'=>'planning.php');

for ($i = 0; $i < $adDisplay AND sizeof($images) > 1; $i++) {
    $k = array_rand(0, sizeof($images)-1);
    $image = $images[$k];
    unset($images[$k];
    sort($images);
    echo '<a href="' . htmlspecialchars($image['cat']) . '">'
         . '<img src="img/banners/'
         . htmlspecialchars($image['img']) . ' border="0" alt="" />'
         . '</a>';
}

So, picks a random key, removes that record from the array, displays it and re-sorts the array for the next go-round. Continues until enough have been displayed or it runs out of records.

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