Dynamically add dimension to PHP array

Question

I thought about it a lot before posting this question.

The question is more conceptual than anything else.

Starting from a classic array, I want to dynamically transform it into multidinamic with subtrees.

to be clear, from this:

$array = ['my', 'unique', 'values', 'array', 'and', 'so', 'on', '...'];

to this:

Array
(
    ['my'] =>
        ['unique'] =>
            ['values'] =>
                ['array'] =>
                    ['and'] =>
                        ['so'] =>
                            ['on']=>
                                ['...'] => []
)

The only attempt I made was "barbarously" to dynamically create strings and pass them with the eval() command.

I don't write the code here for personal dignity. It's bad enough I confessed it. Insiders will understand...

I fully believe that there is a correct way to do it, but of course, if I'm here, I don't know it

Best

Oscar

Nigel Ren · Accepted Answer · 2019-06-17 16:24:35Z

5

This uses references to keep track of what element you are currently adding the data to, so to start $add is the root element (by setting it to &$newArray). Each time it adds a new level it moves the reference to this new item (with &$add[$key]) and repeats the process...

$array = ['my', 'unique', 'values', 'array', 'and', 'so', 'on', '...'];
$newArray = [];
$add = &$newArray;
foreach ( $array as $key )  {
    $add[$key] = [];
    $add = &$add[$key];
}
print_r($newArray);

answered Jun 17, 2019 at 16:24

Nigel Ren

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1 Comment

Oscar Zarrus Over a year ago

I realize to be a duffer. Thanks

The fourth bird · Accepted Answer · 2019-06-17 16:38:06Z

2

Or another option is to create the structure from the outside in using a while loop and decreasing the index on every iteration.

Temporary store what you already have and reset the current $result. Then add an entry with a new key and add the temporary stored variable as the value.

$array = ['my', 'unique', 'values', 'array', 'and', 'so', 'on'];
$result = [];
$tot = count($array) - 1;

while ($tot > -1) {
    $temp = $result;
    $result = [];
    $result[$array[$tot]] = $temp;
    $tot--;
}

print_r($result);

Php demo

edited Jun 17, 2019 at 16:38

answered Jun 17, 2019 at 16:32

The fourth bird

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Comments

Lajos Arpad · Accepted Answer · 2019-06-17 16:17:50Z

1

Start from the end and end with the start:

$length = sizeof($array);
$value = [];
for ($index = $length - 1; $index >= 0; $index--) {
    $value = [
        "{$array[$index]}" => $value
    ];
    unset($array[$index]);
}
$array[]=$value;

answered Jun 17, 2019 at 16:17

Lajos Arpad

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2 Comments

Oscar Zarrus Over a year ago

Vote up without needing to test the code. It was enough for me to have read it. Low level code, as I like it. More than "thank you", I congratulate you !!!

Nigel Ren Over a year ago

You don't really need the unset(), just overwrite the array at the end - $array=$value;

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