How to convert a multidimensional array to a single dimensional array?

Question

I want to turn (in PHP) something like

(["a"] => (
    ["x"] => "foo",
    ["y"] => "bar"),
["b"] => "moo",
["c"] => (
    ["w"] => (
        ["z"] => "cow" )
        )
)

into

(["a.x"] => "foo",
["a.y"] => "bar",
["b"] => "moo",
["c.w.z"] => "cow")

How do I achieve that?

It's arbitrary levels deep, although it rarely goes deeper than 4 levels. — Cobra_Fast, May 12 '11 at 14:07

Felix Kling · Accepted Answer · 2011-05-12T14:15:18.323

7

You could create a recursive function:

function flatten($arr, &$out, $prefix='') {
    $prefix = $prefix ? $prefix . '.' : '';
    foreach($arr as $k => $value) {
        $key =  $prefix . $k;
        if(is_array($value)) {
            flatten($value, $out, $key);
        }
        else {
            $out[$key] = $value;
        }
    }
}

You can use it as

$out = array();
flatten($array, $out);

edited May 12 '11 at 14:15

answered May 12 '11 at 14:08

Felix Kling

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How do I store the full array path as an objects identifier with this one? – Cobra_Fast May 12 '11 at 14:09
@Cobra: I don't know what you mean. Please elaborate. – Felix Kling May 12 '11 at 14:13
$key = $prefix ? $prefix . '.' . $k : $k; It actually already store the full array path with this line. +1 for this solution. – PJP May 12 '11 at 14:14

score 1 · Answer 2 · answered May 12 '11 at 14:07

1

You've got something nice here: http://davidwalsh.name/flatten-nested-arrays-php

answered May 12 '11 at 14:07

PJP

756
3
15

On the right track but that by itself won't make keys like OP wants – CrayonViolent May 12 '11 at 14:10

How to convert a multidimensional array to a single dimensional array?

2 Answers2