Convert a 2d array of path values into a hierarchical multidimensional array

Question

I am trying to create a multidimensional array from a linear array.

This array:

$array = array(
    array('level-one', 'level-two', 'level-three'),
    array('level-one', 'level-two', 'level-three', 'level-four'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 1'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 2'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 3'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 4'),
);

Into:

$multi = array(
    'level-one' => array(
        'level-two' => array(
            'level-three' => array(
                'level-four' => array(
                    'item 1',
                    'item 2',
                    'item 3',
                    'item 4',
                )
            )
        )
    )
);

I guess I should go somehow recursive but I can't find a recursive solution logic.

I must ask why you're doing this. Is this something where you are getting an array from elsewhere that you need to manipulate, or are you generating it? This looks similar to XML; was it originally such? Maybe going this route isn't the right direction and we can do it in another step in the process. — Andrew
– Andrew, Commented Jan 7, 2014 at 14:36
Looking past why you would ever need this, I think the approach in this answer should work with minimal modifications. It is however written in Java, but the approach is rather simple. If you answer shows up here I'll take the time to convert it to PHP after dinner. — atomman
– atomman, Commented Jan 7, 2014 at 15:01
@Andrew I have a PERL script that generates a file KEY1/KEY2/KEY3, and I have to build a navigation from this. So far I've explode(d) the file lines, I had to create a multidimensional array. — Gilberto Albino
– Gilberto Albino, Commented Jan 7, 2014 at 18:11

KorreyD · Accepted Answer · 2014-01-07 15:21:29Z

2

You can give this a go

function to_nested($ary){
    $a = array();
    foreach ( $ary as $rec ){
        $b = &$a;
        $node = null;
        foreach ( $rec as $f ){
            if ( $node !== null ){
                if ( !isset($b[$node]) ){
                    $isleaf = array_search($node,$b);
                    if ( $isleaf !== false )
                        unset($b[$isleaf]);
                    $b[$node] = array();
                }
                $b = &$b[$node];
            }
            $node = $f;
        }
        //push leaf
        if ( empty($b) ){
            $b = array();
        }
        array_push($b, $f);
    }

    return $a;
}

$array = array(
    array('level-one', 'level-two', 'level-three'),
    array('level-one', 'level-two', 'level-three', 'level-four'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 1'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 2'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 3'),
    array('level-one', 'level-two', 'level-three', 'level-four', 'item 4'),
);

print_r(to_nested($array));

result:

Array (
    [level-one] => Array
        (
            [level-two] => Array
                (
                    [level-three] => Array
                        (
                            [level-four] => Array
                                (
                                    [0] => item 1
                                    [1] => item 2
                                    [2] => item 3
                                    [3] => item 4
                                )
                        )
                )
        )
)

I'm not sure what the rules are for your input array so I'd suggest that you play around with different valid inputs to see if the results of this function work for you.

answered Jan 7, 2014 at 15:21

KorreyD

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2 Comments

KorreyD Over a year ago

glad to hear it. oops just noticed, you may surround the //push leaf code with if ( !isset($b[$node]) ){} to prevent a leaf from being created if an array with the same key name already exists on that same level. which could happen if say "array('level-one', 'level-two', 'level-three')," was at the bottom of your example input array instead of at the top.

Gilberto Albino Over a year ago

I thinks the last item of the array must be associative too. Not [0] => item 1 is allowed

Nouphal.M · Accepted Answer · 2014-01-07 15:46:20Z

1

Try

$data=array();
for($i=0;$i<sizeof($array);$i++){
        $tmp=array();
    $data =  array_unique(array_merge($data,$array[$i]));
}

Now duplicate entries have been removed. Now create a multidimensional array

$output=array();
$tmp = &$output;
foreach($data as &$val){
  if(strpos($val,'level') !==false ){
     if (!is_array($tmp)){
          $tmp = array();
      }
      $tmp = &$tmp[$val];

  }else{
    $tmp[] = $val;
  }
}

echo "<pre>";
print_r($output);
exit();

answered Jan 7, 2014 at 15:46

Nouphal.M

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Comments

kba · Accepted Answer · 2014-01-07 16:08:35Z

$last_array = end($array);

// Create an array like your structure, i.e.
// ['level-one', 'level-two', 'level-three', 'level-four'].
$structure = array_slice($last_array, 0, -1);

// Remove all arrays, but the ones with items.
$neat_array = array_filter($array, function($current_array) use ($last_array) {
    return sizeof($current_array) === sizeof($last_array);
});

// Create an array of just your items, i.e.
// ['item 1', 'item 2', 'item 3', 'item 4'].
$items = array_map(function($item) use ($structure) {
    return $item[sizeof($structure)];
}, $neat_array);

// And the final product.
$multi = array_reduce(array_reverse($structure), function($result, $item) {
    return array($item => $result);
}, $items);

print_r($multi);

And the output will be as desired:

Array
(
    [level-one] => Array
        (
            [level-two] => Array
                (
                    [level-three] => Array
                        (
                            [level-four] => Array
                                (
                                    [2] => item 1
                                    [3] => item 2
                                    [4] => item 3
                                    [5] => item 4
                                )

                        )

                )

        )

)

Dharmesh · Accepted Answer · 2014-01-07 15:28:33Z

0

 $array1=array(
  'level1'=>array(
     'level2'=>array(
       'level3'=>array(
          'level4'=>array(
             'A'=>'value1',
                 'B'=>'value2',
                 'C'=>'value3',
                 'D'=>'value4'
             )
           )
         )
       )
    );
    print_r($array1);

answered Jan 7, 2014 at 15:28

Dharmesh

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