Convert an array of strings, each string has dot separated values, to a multidimensional array

Question

I have the following array:

Array
(
    [0] => INBOX.Trash
    [1] => INBOX.Sent
    [2] => INBOX.Drafts
    [3] => INBOX.Test.sub folder
    [4] => INBOX.Test.sub folder.test 2
)

How can I convert this array to a multidimensional array like this:

Array
(
    [Inbox] => Array
        (
            [Trash] => Array
                (
                )

            [Sent] => Array
                (
                )

            [Drafts] => Array
                (
                )

            [Test] => Array
                (
                    [sub folder] => Array
                        (
                            [test 2] => Array
                                (
                                )

                        )

                )

        )

)

possible duplicate of [String with array structure to Array](http://stackoverflow.com/questions/8537148/string-with-array-structure-to-array) — Jon, Feb 28 '13 at 10:32
I'm having immense difficulty trying to do this! Would be cool to see an answer.. — Matt Humphrey, Feb 28 '13 at 10:36

score 4 · Accepted Answer · edited Mar 15 '23 at 18:50

This code uses a function from this answer to do what you're looking for.

<?php
$test = Array
(
    0 => 'INBOX.Trash',
    1 => 'INBOX.Sent',
    2 => 'INBOX.Drafts',
    3 => 'INBOX.Test.sub folder',
    4 => 'INBOX.Test.sub folder.test 2',
);

$output = array();
foreach($test as $element){
    assignArrayByPath($output, $element);   
}
debug($output);

function assignArrayByPath(&$arr, $path) {
    $keys = explode('.', $path);
    
    while ($key = array_shift($keys)) {
        $arr = &$arr[$key];
    }
}

function debug($arr){
    echo "<pre>";
    print_r($arr);
    echo "</pre>";
}

score 0 · Answer 2 · answered Feb 28 '13 at 10:52

I was very interested in this as was having immense difficulty trying to do this. After looking at (and going through) Jon's solution I have come up with this:

$array = array();
function parse_folder(&$array, $folder)
{
    // split the folder name by . into an array
    $path = explode('.', $folder);

    // set the pointer to the root of the array
    $root = &$array;

    // loop through the path parts until all parts have been removed (via array_shift below)
    while (count($path) > 1) {
        // extract and remove the first part of the path
        $branch = array_shift($path);
        // if the current path hasn't been created yet..
        if (!isset($root[$branch])) {
            // create it
            $root[$branch] = array();
        }
        // set the root to the current part of the path so we can append the next part directly
        $root = &$root[$branch];
    }
    // set the value of the path to an empty array as per OP request
    $root[$path[0]] = array();
}

foreach ($folders as $folder) {
    // loop through each folder and send it to the parse_folder() function
    parse_folder($array, $folder);
}

print_r($array);

Convert an array of strings, each string has dot separated values, to a multidimensional array

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