Recursive walking through a PHP multidimensional array to make a comparison

Question

I have a large array converted from a JSON structure with an unknown number of elements and sublevels.

Something like:

$marr = array
(
    "Order" => array
    (
        "Details" => array
        (
            "Document" => array
            (
                "Number" => "1585636772",
                "Date" => "2014-12-31"
            ),
            "Delivery" => array
            (
                "Date" => "2015-01-02",
                "TrackingCode" => "5703",
                "Name" => "Example Name",
                "Address" => "Example Address"
            )
        )
    )
);

And on the other hand, I have an array of items I need to compare and find out if they are in the array above. This "indexer" will always mirror the same structure above (it's generated before the comparison step) because I thought that would help me ensure a proper comparison in an easier way.

Something like:

$indexer = array
(
    "Order" => array
    (
        "Details" => array
        (
            "Document" => array
            (
                "Date" => "variable_name_1"
            ),
            "Delivery" => array
            (
                "Date" => "variable_name_2"
            )
        )
    )
);

I'm not entirely sure how best to compare these. I have looked into array_walk_recursive() which only returns the leaf values and I have tried to write my own attempts at a basic recursive function that would perform a foreach() which would then try to do something like:

if( isset($marr["Order"]["Details"]["Document"]["Date"]) )
{
    $store[ $indexer["Order"]["Details"]["Document"]["Date"] ] = $marr["Order"]["Details"]["Document"]["Date"];
}

So that at the end I would have a basic array that stored all values found on $marr under an alias that was listed on $indexer. Like this:

$store["variable_name_1"] = "2014-12-31";
$store["variable_name_2"] = "2015-01-02";

This has been a headache for two days now and I can't seem to figure out the best way to go through this. I'm trying to walk through $indexer to reach its ending, obtain the "variable name", and then compare with $marr to store its data, but I always seem to lose the parent nodes of $indexer while trying to do this recursively. I would appreciate any advice at all.

How do you get "variable_name_1" and two? Do these names matter? — Kalkran
– Kalkran, Commented Feb 23, 2016 at 12:33
Not sure, why you need an recursive function.. Just create an nested loop — Philipp
– Philipp, Commented Feb 23, 2016 at 12:33
@Kalkran those names are in $indexer, they are in theory needed because I want to store the data from the JSON web service to use in a bunch of SQL queries. They are just example names here, in theory I could have, says, twenty of these to use in five different queries. But that's a different logic step for the application I'm trying to build and not relevant here, I imagine. — Ivo
– Ivo, Commented Feb 23, 2016 at 12:38

trincot · Accepted Answer · 2016-02-23 12:39:36Z

2

You could use this recursive function:

function storeFromIndex($marr, $indexer) {
    if (!is_array($indexer)) {
        return array($indexer => $marr);
    }
    $store = [];
    foreach($indexer as $key => $subindexer) {
        $store = array_merge($store, storeFromIndex($marr[$key], $subindexer));
    }
    return $store;
}

And then call it like this:

$store = storeFromIndex($marr, $indexer);

With the example data given, $store will be:

array (
  'variable_name_1' => '2014-12-31',
  'variable_name_2' => '2015-01-02',
)

answered Feb 23, 2016 at 12:39

trincot

357k38 gold badges282 silver badges338 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Ivo Over a year ago

Jesus, it's perfect in its simplicity! Thank you so much.

Chetan Ameta · Accepted Answer · 2016-02-23 12:48:31Z

Here I would like to suggest do not maintain indexer, you can use iterator and create new array using associated keys.

For example have a look on below solution:

$array = array
(
    "Order" => array
    (
        "Details" => array
        (
            "Document" => array
            (
                "Number" => "1585636772",
                "Date" => "2014-12-31"
            ),
            "Delivery" => array
            (
                "Date" => "2015-01-02",
                "TrackingCode" => "5703",
                "Name" => "Example Name",
                "Address" => "Example Address"
            )
        )
    )
);


$new_array = array();
$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));

foreach ($iterator as $key => $value) {
    $keys = array();
    $keys[] = $key;
    for ($i = $iterator->getDepth() - 1; $i >= 0; $i--) {
        $keys[] = $iterator->getSubIterator($i)->key();
    }
    $key_paths = array_reverse($keys);
    $new_array[implode('_', $key_paths)] = $value;
}

print_r($array);
print_r($new_array);

Output:

Array
(
    [Order] => Array
        (
            [Details] => Array
                (
                    [Document] => Array
                        (
                            [Number] => 1585636772
                            [Date] => 2014-12-31
                        )

                    [Delivery] => Array
                        (
                            [Date] => 2015-01-02
                            [TrackingCode] => 5703
                            [Name] => Example Name
                            [Address] => Example Address
                        )

                )

        )

)
Array
(
    [Order_Details_Document_Number] => 1585636772
    [Order_Details_Document_Date] => 2014-12-31
    [Order_Details_Delivery_Date] => 2015-01-02
    [Order_Details_Delivery_TrackingCode] => 5703
    [Order_Details_Delivery_Name] => Example Name
    [Order_Details_Delivery_Address] => Example Address
)

This isn't a bad solution and I wasn't aware of those recursive iterator classes, thanks.

Collectives™ on Stack Overflow

Recursive walking through a PHP multidimensional array to make a comparison

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related