Method to convert an associative array into an indexed array

Question

I have an associative array with indexed sub-arrays each containing associative arrays which contain content and an index. So like this (in PHP):

$assoc_arr = 
array("second" => array(
                       array("position" => 4,
                             "content" => "Valiant"),
                       array("position" => 5,
                             "content" => "Hail")
                      ),
      "first" =>  array(
                       array("position" => 0,
                             "content" => "Hail"),
                       array("position" => 3,
                             "content" => "Victors"),
                       array("position" => 2,
                             "content" => "the"),
                       array("position" => 1,
                             "content" => "to")
                      )
);

I want to put all of those into an indexed array where their index is their "position" in the associative array. So final array should be:

Array ( [0] => Hail [1] => to [2] => the [3] => Victors [4] => Valiant [5] => Hail )

Currently, I'm merging all of the arrays inside the highest level array, then sorting it by each of those sub-array's positions, then creating an indexed array by pushing the content in order onto a new array. As so:

$pos_arr = array_merge($assoc_arr["second"], $assoc_arr["first"]);
usort($pos_arr, function($a, $b) {
  return $a["position"] >= $b["position"] ? 1 : -1;
});

$indexed_arr = array();

foreach ($pos_arr as $elem) {
    array_push($indexed_arr, $elem["content"]);
}

It seems like there must be a better way to do this! Can anyone think of one?

The data is coming from a poorly structured XML document which I can't change.

Eugen Rieck · Accepted Answer · 2014-04-30 17:52:22Z

1

$idxar=array();
foreach ($assoc_arr as $subar)
  foreach ($subar as $item)
    $idxar[$item['position']+0]=$item['content'];

will work, if your input data is flawless.

Edit

If you need the keys not only to be numerically correct, but also in the correct order, you must suffix this with ksort($idxar)

answered Apr 30, 2014 at 17:52

Eugen Rieck

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Comments

Guns · Accepted Answer · 2014-04-30 18:01:19Z

here is another solution:

<?php

$assoc_arr = 
    array("second" => array(
        array("position" => 4,
              "content" => "Valiant"),
        array("position" => 5,
              "content" => "Hail")
        ),
    "first" =>  array(
        array("position" => 0,
              "content" => "Hail"),
        array("position" => 3,
              "content" => "Victors"),
        array("position" => 2,
              "content" => "the"),
        array("position" => 1,
              "content" => "to")
      )
);

$order = array('first','second'); // this helps you create your own sort. E.g. position1, position2, etc
$arr = array();

foreach($order as $ord) {
    if(isset($assoc_arr[$ord])) {
       $arr = array_merge($arr, $assoc_arr[$ord]);
    }
}

$finalArray = array();

foreach($arr as $a) {
    $finalArray[$a['position']] = $a['content'];
}

ksort($finalArray);

print_r($finalArray);

and a fiddle that works for you here

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