PHP render array to flat array with parent key in front

Question

I have a array that i want to flatten, but i want to add a backslash and all the parent keys to it. I have a example below, can someone help me out? The array can contain more 5 levels

Cars
    Mercedes
    BMW
    Chevrolet
        Caprice
        Other
Motors
    Yamaha
    Suzuki


Cars
Cars\Mercedes
Cars\BMW
Cars\Chevrolet
Cars\Chevrolet\Caprice
Cars\Chevrolet\Other
Motors
Motors\Yamaha
Motor\Suzuki

What have you tried? You will need a recursive function that checks if the child is an array, and then do that function for each child, etc. — Sean
– Sean, Commented Feb 14, 2016 at 20:48

Hiphop03199 · Accepted Answer · 2016-02-14 20:57:56Z

4

I've made a quick demo of what you've asked for, but not sure how similar your array matches up to the test one I have here. Let me know if you need some more help, it's an interesting problem.

<?php
$arr = array(
    'val1' => 1,
    'val2' => 2,
    'val3' => array(
        'val3.1' => 1,
        'val3.2' => array(
            'val3.2.1' => 1
            ),
        'val3.3' => 3
        ),
    'val4' => 4
);

function arrayToPath($array, $path = ''){
    $paths_out = array(); 

    foreach($array as $key => $value){
        $path .= '\\' . $key;
        $paths_out[] = $path;
        if(true === is_array($value)){
            $paths_out = array_merge($paths_out, arrayToPath($value, $path));
        }
    }

    return $paths_out;
}

$path_outputs = arrayToPath($arr);
var_dump($path_outputs);
?>

Will output:

array(8) { 
    [0]=> string(5) "\val1" 
    [1]=> string(10) "\val1\val2" 
    [2]=> string(15) "\val1\val2\val3" 
    [3]=> string(22) "\val1\val2\val3\val3.1" 
    [4]=> string(29) "\val1\val2\val3\val3.1\val3.2" 
    [5]=> string(38) "\val1\val2\val3\val3.1\val3.2\val3.2.1" 
    [6]=> string(36) "\val1\val2\val3\val3.1\val3.2\val3.3" 
    [7]=> string(20) "\val1\val2\val3\val4" 
}

answered Feb 14, 2016 at 20:57

Hiphop03199

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4 Comments

arkascha Over a year ago

Impressive, we both posted a very similar answer in practically the same second :-)

Hiphop03199 Over a year ago

I was just thinking the same thing :) Great minds or something, eh?

arkascha Over a year ago

OK, great minds deserve a reward, just upvoted your answer :-)

C Würtz Over a year ago

I notice your nice condition statement: constant strict-operator function

arkascha · Accepted Answer · 2016-02-14 21:04:55Z

3

Have a try with this simple recursive approach:

<?php

$catalog = [
    'Cars' => [
        'Mercedes' => [],
        'BMW' => [],
        'Chevrolet' => [
            'Caprice',
            'Other'
        ],
    ],
    'Motors' => [
        'Yamaha',
        'Suzuki'
    ]
];

function flattenCatalog($input, $location='') {
    $output = [];
    foreach ($input as $key=>$val) {
        if (is_array($val)) {
            $output[] = $location.'\\'.$key;
            foreach (flattenCatalog($val, $location.'\\'.$key) as $subval) {
                $output[] = $subval;
            }
        }
        else {
            $output[] = $location.'\\'.$val;
        }
    }
    return $output;
}

print_r(flattenCatalog($catalog));

The output obviously is:

Array
(
    [0] => \Cars
    [1] => \Cars\Mercedes
    [2] => \Cars\BMW
    [3] => \Cars\Chevrolet
    [4] => \Cars\Chevrolet\Caprice
    [5] => \Cars\Chevrolet\Other
    [6] => \Motors
    [7] => \Motors\Yamaha
    [8] => \Motors\Suzuki
)

edited Feb 14, 2016 at 21:04

answered Feb 14, 2016 at 20:58

arkascha

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5 Comments

Hiphop03199 Over a year ago

At a glance, your solution looks slightly more flexible than mine in accepting array entries which are value-only. My sample needs a small tweak to accommodate anything that isn't an associative pair.

arkascha Over a year ago

@Hiphop03199 That is indeed what I understood to be the challenge in this question. Your answer is slightly more compact, though.

Donny van V Over a year ago

Thats a sweet function :) only 1 issue: take a look at this paste: laravel.io/bin/d9Drn that is my array. Using your function gets me: laravel.io/bin/KknYV so it also gives the created_at (Laravel fields) back to me :P

arkascha Over a year ago

Sorry, I fail to see an issue here. Your question asks to flatten all entries in the given array. That is what the function does. It cannot somehow magically guess what entries you might want to skip. If you have clear rules about those exception, then you can either extend the routine by implementing exceptions, or, more effective, you clean the input array before flattening it.

Donny van V Over a year ago

Yeah i don't blame you Arka, you gave me a direction and thats something i really appreciate :) You couldn't know that it has integer keys instead of text only. Sorry i forgot to mention.

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