Split php multidimensional array into sub-array as soon as a repeating value found

Question

I am having an issue splitting a multidimensional array into sub-arrays based on repeating values. Here is the issue-

Current array:

Array (
    [2] => first=1
    [3] => second=2
    [4] => third=
    [5] => first=4
    [9] => second=3
    ...
);

Intended result:

Array(
    [0] =>
        Array(
            [first] => 1,
            [second] => 2,
            [third] => 
        ...
    ),
    [1] =>
        Array(
            [first] => 4,
            [second] => 3
        ...
    ),
);

Trying to achieve by manipulating it like this but stuck this far-

$filtered_array_splitted = [];
$array_tracker = 0;
$array_tracker_in = 0;
foreach ($filtered_array as $key => $value) {

    parse_str(str_replace('', '=', $value), $mapped_value_as_pair);

    $filtered_array_splitted[$array_tracker++] = array_merge($mapped_value_as_pair);
}

print_r($filtered_array_splitted);

This just split them into sub-arrays, I need to insert them based on duplication occurrence. Anytime same key is found, new sub-array will be formed.

Nigel Ren · Accepted Answer · 2020-05-18 18:48:51Z

1

This keeps a list of the current list of fields being added, then if it finds one that is already present (using isset()), then it stores the list and starts again.

At the end if there are any left over, it adds them into the final list...

$filtered_array_splitted = [];
$current_list = [];
foreach ($filtered_array as $string) {
    list($name, $value) = explode("=", $string);
    if ( isset($current_list[$name]) ){
        $filtered_array_splitted[] = $current_list;
        $current_list = [];
    }
    $current_list[$name] = $value;
}
if ( !empty($current_list)) {
    $filtered_array_splitted[] = $current_list;
}

answered May 18, 2020 at 18:48

Nigel Ren

57.3k11 gold badges49 silver badges59 bronze badges

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

2 Comments

RP McMurphy Over a year ago

Worked like a charm! Could you explain a bit line 6 and 7?

Nigel Ren Over a year ago

$filtered_array_splitted[] takes the list of items so far added and just appends it to the array, the next line just resets the array so all of the previous list of items are removed. (hope this is the right lines).

mickmackusa · Accepted Answer · 2020-11-30 10:18:13Z

A reference variable is the perfect tool to keep the script concise, clean, and direct.

Every iteration of the loop must push a value. It is the destination of the pushed value that must be dynamic.

By "pre-pushing" the reference variable into the output array when:

there is no reference variable yet or
the current reference variable already has a specific key

you never need to mop up after looping.

Think of $entry as a basketball hoop -- you always shoot into the hoop. The "trick" is that you can move the hoop to wherever you like.

Code: (Demo)

$array = [
    2 => 'first=1',
    3 => 'second=2',
    4 => 'third=',
    5 => 'first=4',
    9 => 'second=3',
];

$result = [];
foreach ($array as $string) {
    [$key, $value] = explode('=', $string, 2);

    if (!isset($entry) || isset($entry[$key])) {
        unset($entry);
        $result[] = &$entry;
    }
    $entry[$key] = $value;
}
var_export($result);

Output:

array (
  0 => 
  array (
    'first' => '1',
    'second' => '2',
    'third' => '',
  ),
  1 => 
  array (
    'first' => '4',
    'second' => '3',
  ),
)

p.s. the unset() call is not necessary before $entry is declared the first time, but it must be called before each subsequent push so that the reference variable is "reset" so-to-speak.

Collectives™ on Stack Overflow

Split php multidimensional array into sub-array as soon as a repeating value found

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related