CODEWITHSUNDEEP
phparrays
Dropout
Dropout

Reputation: 13866

Pushing random array elements into another array in PHP

I have an array consisting of N>10 URLs. I want to randomly pick 10 of them and store them in another array. How can I achieve this? Is array_rand() the way to go? If yes, then how do I ensure that there are no duplicities in the output array? Do I have to check the second array everytime a new element is added for existence?

// $firstArray is defined earlier
$secondArray = array();
array_push(array_rand($firstArray, 10));

This doesn't work unfortunately. I was thinking about using a for cycle for the array_push() but I was just curious if array_rand() can do that for me.

Thanks for advice!

Upvotes: 0

Views: 2257

Answers (6)

Adi Scoarta
Adi Scoarta

Reputation: 36

If you use array_push like in the example code, the last index in your second array will contain the returned 10 indexes

Eg.

$stack = array('a', 'b', 'c');
array_push($stack, array('d', 'e', 'f'));
print_r($stack);

Array (
  [0] => a
  [1] => b
  [2] => c
  [3] => Array (
     [0] => d
     [1] => e
     [2] => f
  )
)

I would use a while in this case and pick only one value at a time. Something like:

$stack = array();
while(count($stack)<10){
    $item = array_rand($collection_of_urls);
    if(!in_array($item)
        array_push($stack, $item);
}

Upvotes: 1

aleation
aleation

Reputation: 4844

As people said there is a second argument in array_rand() to pick how many random elements you want, always remember to read the Manual

//Lets pick 10 mammals
$mammals = array('dog', 'cat', 'pig', 'horse', 'bat', 'mouse', 'platypus', 'bear', 'donkey', 'deer', 'hog', 'duck');
$ten = array_rand(array_flip($mammals), 10);

//If what yo u really wanted is to append them to another array, let's say "animals":
$animals = array('fish', 'crab', 'whale', 'eagle');
$animals = array_merge($animals, array_rand(array_flip($mammals), 10));

Explanation array_rand() will return you the keys, so we can use array_flip() here to reverse the keys => values positions before picking them, no need to loop through them again.

And using array_merge() we merge them together, with no need to loop through the ten random elements to add them one by one, unless ... you want a specific order or other logic.

Upvotes: 2

Amal Murali
Amal Murali

Reputation: 76656

This can be done without array_rand(). Use shuffle() to shuffle the array elements and then use array_slice() to get the first 10 items:

$secondArray = array();
shuffle($firstArray);
$secondArray = array_slice($firstArray, 0, 10);

Demo!

Upvotes: 2

Xpundel
Xpundel

Reputation: 81

Not very optimized solution, but for small amounts of data it may suit:

$firstArray = array(1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9);
$secondArray = array();

$tmp = array_unique($firstArray);
shuffle($tmp);
$secondArray += array_slice($tmp,0, 10);

Upvotes: 1

StreetCoder
StreetCoder

Reputation: 10061

this simple

$rand_keys = array_rand($input, 10);
print_r($rand_keys);

Upvotes: 0

litechip
litechip

Reputation: 336

array_rand returns keys so 

$randKeys = array_rand($firstArray, 10);
foreach($randKeys as $key)
$secondArray[] = $firstArray[$key]

Upvotes: 3

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