How to randomly loop through first layer of nested associative array in PHP?

Question

I have a nested assocative array which might look something like this:

$myarray = array(
  ['tiger'] => array(
    ['people'], ['apes'], ['birds']
  ),
  ['eagle'] => array(
    ['rodents'] => array(['mice'], ['squirrel'])
  ),
  ['shark'] => ['seals']
);

How can I loop through the first layer (tiger, eagle, shark) in a random order and ensure that I cover them all in my loop? I was looking at the PHP function shuffle();, but I think that function messes up the whole array by shuffling all layers.

Get Off My Lawn · Accepted Answer · 2012-12-27 18:03:40Z

2

You can randomly sort an array like this, it will keep the keys and the values

<?php
$myarray = array(
  'tiger' => array(
    'people', 'apes', 'birds'
  ),
  'eagle' => array(
    'rodents' => array('mice', 'squirrel')
  ),
  'shark' => 'seals'
);

$shuffleKeys = array_keys($myarray);
shuffle($shuffleKeys);
$newArray = array();
foreach($shuffleKeys as $key) {
    $newArray[$key] = $myarray[$key];
}

print_r($newArray);

answered Dec 27, 2012 at 18:03

Get Off My Lawn

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Comments

Carsten · Accepted Answer · 2012-12-27 18:06:32Z

1

You can get the keys using array_keys(). Then you can shuffle the resulting key array using shuffle() and iterate through it.

Example:

$keys = array_keys($myarray);
shuffle($keys);
foreach ($keys as $key) {
  var_dump($myarray[$key]);
}

answered Dec 27, 2012 at 18:06

Carsten

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Comments

MrGlass · Accepted Answer · 2012-12-27 18:05:17Z

0

According to my test, shuffle only randomizes 1 layer. try it yourself:

<?php
$test = array(
        array(1,2,3,4,5),
        array('a','b','c','d','e'),
        array('one','two','three','four','five')
    );
shuffle($test);
var_dump($test);
?>

answered Dec 27, 2012 at 18:05

MrGlass

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2 Comments

Carsten Over a year ago

shuffle does not preserve an array's keys. Please see the notes in the docs: php.net/manual/en/function.shuffle.php

MrGlass Over a year ago

I didn't see before i answered, you are using an associative array. That means you have named keys, IE $array['name'] = 'Bob'; $array['phone'] = '555-4202', instead of $array[0] = 'Bob'; $array[1] = '555-4202'. When you use shuffle, it mixes up the keys, so now $array['name']` might equal '555-4202'. This doesn't matter for numbered arrays, but for named array it will ruin your data.

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