How would I split multiple strings into a deep nested array?

Question

I have multiple strings similar to:

$str = "/One/Two";
$str2 = "/One/Two/Flowers";
$str3 = "/One/Two/Grass";
$str4 = "/One/Another/Deeper";
$str5 = "/Uno/Dos/Cow";

I want to split it into a deep nested array that looks similar to the following:

Array
(
    [One] => Array 
    (
        [Two] => Array
        (
            [Flowers] => 
            [Grass] => 
        )    
        [Another] => Array
        (
            [Deeper] => 
        )           
    )   
    [Uno] => Array 
    (
        [Dos] => Array
        (
            [Cow] => 
        )             
    )         
)

Tatu Ulmanen · Accepted Answer · 2010-11-02 15:52:12Z

5

This should do it:

$strings = array(
    "/One/Two",
    "/One/Two/Flowers",
    "/One/Two/Grass",
    "/One/Another/Deeper",
    "/Uno/Dos/Cow"

);

$result = array();

foreach($strings as $string) {
    $parts = array_filter(explode('/', $string));

    $ref = &$result;
    foreach($parts as $p) {
        if(!isset($ref[$p])) {
            $ref[$p] = array();
        }
        $ref = &$ref[$p];
    }
    $ref = null;
}

print_r($result);

Working example:

http://codepad.org/GmAoXLXp

answered Nov 2, 2010 at 15:52

Tatu Ulmanen

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3 Comments

erisco Over a year ago

I think some of the code in this solution is a bit redundant but mainly I am just bitter at the lack of recognition for a couple second late answer =\

Tatu Ulmanen Over a year ago

@erisco, if by redundant you refer to the isset part, it actually is necessary, referencing an uninitialized variable will throw a notice. And setting $ref to null at the end prevents references from showing up in the final array. Other than that, our codes seem to be pretty identical. +1 for that :)

erisco Over a year ago

I +1 you as well, thanks :) PHP doesn't care if you reference a variable that has not yet been declared. Instead of throwing a notice it will just initialize it to null. Tricks of the trade! Now don't go neglecting to test for $_POST and $_GET keys...

erisco · Accepted Answer · 2010-11-02 15:57:23Z

1

Something like this should work. I couldn't think of any nice functional way to build the structure, so I fell back to a couple foreach loops.

<?php

$strings = array(
    '/One/Two',
    '/One/Two/Flowers',
    '/One/Two/Grass',
    '/One/Another/Deeper',
    '/Uno/Dos/Cow'
);

$paths = array_map(
    function ($e) {
        return explode('/', trim($e, '/'));
    },
    $strings
);

$pathStructure = array();

foreach ($paths as $path) {
    $ref =& $pathStructure;
    foreach ($path as $dir) {
        $ref =& $ref[$dir];
    }
}
unset($ref);

print_r($pathStructure);

answered Nov 2, 2010 at 15:57

erisco

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1 Comment

Ahungry Over a year ago

Thank you for taking the time with this question erisco, I already put my checkmark on Tatu's, but your method works as well. I will study both and figure out how this was done.

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