遍历php多级关联数组

Question

I am struggling to return values from all layers of a multidimensional array, eg value then all child elements. I've tried lots of loops but can't quite get it right. Please can someone help - I've been stuck for ages! Thank you.

The array is:

Array
(
    [SiteRep] => Array
        (   [DV] => Array
                (
                    [Location] => Array
                        (
                            [Period] => Array
                                (
                                    [0] => Array
                                        (
                                            [value] => 2016-12-19Z
                                            [Rep] => Array
                                                (
                                                    [0] => Array
                                                        (
                                                            [D] => W
                                                            [F] => 1
                                                            [G] => 9
                                                        )

                                                    [1] => Array
                                                        (
                                                            [D] => W
                                                            [F] => 0
                                                            [G] => 7
                                                        )

                                                )
                                        )

                                    [1] => Array
                                        (
                                            [value] => 2016-12-20Z
                                            [Rep] => Array
                                                (
                                                    [0] => Array
                                                        (
                                                            [D] => ENE
                                                            [F] => 4
                                                            [G] => 7

                                                        )

                                                    [1] => Array
                                                        (
                                                            [D] => E
                                                            [F] => 3
                                                            [G] => 9

                                                        )

so far my code is:

$i=0;
    foreach ($json_decoded['SiteRep']['DV']['Location']['Period'][$i] as $key => $value) {
    if (is_array($value)){
        foreach ($value as $key2 => $value2){
            if (is_array($value2)){
                foreach ($value2 as $key3 => $value3) {
                    echo $key3 . " 3: " . $value3 . "<br>";
                }
            } else {
                echo $key2 . " 2: " . $value2 . "<br>";
            }
        };

    } else {
        echo $key . " 1: " . $value . "<br>";
    }
    $i++;
};

Answer 1

I believe you are looking for recursion. A function that calls itself. It can be tricky but it is by far the most efficient way to navigate an array of indeterminate depth.

function printStuff($stuff)
{
  echo $stuff['value']
  if (isset($stuff['rep']))
  {
    printStuff($stuff['rep']);
  }
}

If you want the values to pass down simply change echo to a return value:

function printStuff($stuff)
{
  $temp = $stuff['value']
  if (isset($stuff['rep']))
  {
    $temp .= printStuff($stuff['rep']);
  }
  return $temp;
}

Note: recursion can cause out of memory if not set up correctly similar to an infinite loop, as the recursive function call pushes the function call onto the call stack every time. Just make sure your function call has a subset of the parameter passed in.

Answer 2

If your array has the constantly number of layers, you may use foreach-function for the each layer. If your array has different number of layers every time - you should use the recursion, because it's the only solution in your situation.

Something like this:

array_walk_recursive($array, function($item, $key){
    //your actions
});

Answer 3

I've continued drilling down and managed to get all the data I need by using...

foreach ($json_decoded['SiteRep']['DV']['Location']['Period'] as $key => $value) {
if (is_array($value)){
    foreach ($value as $key2 => $value2){
        if (is_array($value2)){
            foreach ($value2 as $key3 => $value3) {
                foreach ($value3 as $key4 => $value4) {
                    echo $key4 . ": " . $value4 . "<br>";
                }
            }
        } else {
            echo $key2 . ": " . $value2 . "<br>";
        }
    };
} else {
    echo $key . ": " . $value . "<br>";
}
$i++;

};

Answer 4

This can map the array recursivly. Preserving they keys and structure. You can however only return a new value and not change the key. But you will know which key you are looking at and if you just want to echo it you can do that to.

array_map_assoc_recursive('callback', $array)

function callback($key, $value) {
    return "new" . $value;
}


function array_map_assoc_recursive($f, array $a) {
    return array_column(array_map(function ($key, $value) use ($f) {
        if (is_array($value)) {
            return [$key, array_map_assoc_recursive($f, $value)];
        } else {
            return [$key, call_user_func($f, $key, $value)];
        }
    }, array_keys($a), $a), 1, 0);
}