PHP How To Turn Nested Foreach Into An Array of Arrays (Multidimensional Array)

Question

I'm sorry because I'm probably not going to use the correct vocabulary here, but I'm trying to figure out "how-to" modify the following code so that it creates the array of arrays (Multidimensional Array). This code creates the structure illustrated in the image below, but I want it to create the array of arrays (Multidimensional Array) instead.

Basically, I want the 1001, 1002, 1004, etc... to be the main array. The nested arrays will be the strings that has the #1001, #1002, etc... in them. You'll notice the # in the string corresponds with number in the original array.

$combinedAssignmentData = []; 
foreach($assignmentsYES as $key=>$assignedIDs){
  $levels = array($assignedIDs);
    foreach($levels as $key=>$level){
      echo "<strong>$level</strong><br>";
      foreach($studentIDsubmissions as $k=>$individualSubmission){
        if (strpos($individualSubmission, $level) !== false) {
          echo "--$individualSubmission<br>";
        }
      }
    }
}

var_export($assignmentsYES);

array ( 0 => '1001', 1 => '1002', 2 => '1004', 3 => '1005', 4 => '1007', 5 => '1008', 6 => '1009', 7 => '1015', 8 => '1028', 9 => '1029', )

var_export($studentIDsubmissions);

array ( 0 => '[email protected]|TD-Share Test #1001|NO', 1 => '[email protected]|TD-Share Test #1001|NO', 2 => '[email protected]|TD-Share Test #1001|NO', 3 => '[email protected]|TD-Share Test #1001|NO', 4 => '[email protected]|TD-No Excuse Reflection #1002|YES', 5 => '[email protected]|TD-No Excuse Reflection #1002|YES', 6 => '[email protected]|TD-No Excuse Reflection #1002|YES', 7 => '[email protected]|TD-About Me #1004|YES', 8 => '[email protected]|TD-Calendar #1007|YES', 9 => '[email protected]|TD-Wage Tracker #1008|YES', 10 => '[email protected]|TD-Stock Portfolio #1009|YES', 11 => '[email protected]|TD-Collaboration #1005|YES', 12 => '[email protected]|TD-Stock Portfolio #1009|YES', 13 => '[email protected]|TD-Collaboration #1005|YES', 14 => '[email protected]|TD-Dream Vacation Presentation #1015|YES', )

Any help is greatly appreciated! Todd

It would be much easier if you had some sample data of this $assignmentsYES (use var_export, if you add any) — ArtisticPhoenix
– ArtisticPhoenix, Commented Apr 3, 2019 at 4:09
I actually had it written before you posted the data ... lol — ArtisticPhoenix
– ArtisticPhoenix, Commented Apr 3, 2019 at 4:19

ArtisticPhoenix · Accepted Answer · 2019-04-03 04:44:08Z

Here you go

$assignmentsYES = array ( 0 => '1001', 1 => '1002', 2 => '1004', 3 => '1005', 4 => '1007', 5 => '1008', 6 => '1009', 7 => '1015', 8 => '1028', 9 => '1029', );
$studentIDsubmissions = array ( 0 => '[email protected]|TD-Share Test #1001|NO', 1 => '[email protected]|TD-Share Test #1001|NO', 2 => '[email protected]|TD-Share Test #1001|NO', 3 => '[email protected]|TD-Share Test #1001|NO', 4 => '[email protected]|TD-No Excuse Reflection #1002|YES', 5 => '[email protected]|TD-No Excuse Reflection #1002|YES', 6 => '[email protected]|TD-No Excuse Reflection #1002|YES', 7 => '[email protected]|TD-About Me #1004|YES', 8 => '[email protected]|TD-Calendar #1007|YES', 9 => '[email protected]|TD-Wage Tracker #1008|YES', 10 => '[email protected]|TD-Stock Portfolio #1009|YES', 11 => '[email protected]|TD-Collaboration #1005|YES', 12 => '[email protected]|TD-Stock Portfolio #1009|YES', 13 => '[email protected]|TD-Collaboration #1005|YES', 14 => '[email protected]|TD-Dream Vacation Presentation #1015|YES', );

$combinedAssignmentData = []; 
foreach($assignmentsYES as $key=>>$level){
        $combinedAssignmentData[$level] = 
                array_filter(
                    $studentIDsubmissions,
                    function($item)use($level){
                        return strpos($item, '#'.$level) !== false;
                    }
                );
}

print_r($combinedAssignmentData);

Output

Array
(
    [1001] => Array
        (
            [0] => [email protected]|TD-Share Test #1001|NO
            [1] => [email protected]|TD-Share Test #1001|NO
            [2] => [email protected]|TD-Share Test #1001|NO
            [3] => [email protected]|TD-Share Test #1001|NO
        )

    [1002] => Array
        (
            [4] => [email protected]|TD-No Excuse Reflection #1002|YES
            [5] => [email protected]|TD-No Excuse Reflection #1002|YES
            [6] => [email protected]|TD-No Excuse Reflection #1002|YES
        )

    [1004] => Array
        (
            [7] => [email protected]|TD-About Me #1004|YES
        )

    [1005] => Array
        (
            [11] => [email protected]|TD-Collaboration #1005|YES
            [13] => [email protected]|TD-Collaboration #1005|YES
        )

    [1007] => Array
        (
            [8] => [email protected]|TD-Calendar #1007|YES
        )

    [1008] => Array
        (
            [9] => [email protected]|TD-Wage Tracker #1008|YES
        )

    [1009] => Array
        (
            [10] => [email protected]|TD-Stock Portfolio #1009|YES
            [12] => [email protected]|TD-Stock Portfolio #1009|YES
        )

    [1015] => Array
        (
            [14] => [email protected]|TD-Dream Vacation Presentation #1015|YES
        )

    [1028] => Array
        (
        )

    [1029] => Array
        (
        )

)

Sandbox

*PS I added a # in here strpos($item, '#'.$level), which will improve the accuracy a bit. It would be better to use a regular expression (in the array filter callback)

function($item)use($level){
   return preg_match('/#'.$level.'\|/', $item); //match `#{id}|`
}

Consider for example matching 1001 to id 10012 ~ strpos will just match the 1001 part with no regard.

If the oddly numbered keys for the sub array bug you you can wrap the array_filter in array_values(array_filter(....)); to reset them. Array filter retains the keys from the original array. In most cases the keys don't really matter, so I wouldn't worry about it unless you really have to.

Update

After thinking about it and posting this

be better to use a regular expression

Why don't we go with this one:

$assignmentsYES = array ( 0 => '1001', 1 => '1002', 2 => '1004', 3 => '1005', 4 => '1007', 5 => '1008', 6 => '1009', 7 => '1015', 8 => '1028', 9 => '1029', );
$studentIDsubmissions = array ( 0 => '[email protected]|TD-Share Test #1001|NO', 1 => '[email protected]|TD-Share Test #1001|NO', 2 => '[email protected]|TD-Share Test #1001|NO', 3 => '[email protected]|TD-Share Test #1001|NO', 4 => '[email protected]|TD-No Excuse Reflection #1002|YES', 5 => '[email protected]|TD-No Excuse Reflection #1002|YES', 6 => '[email protected]|TD-No Excuse Reflection #1002|YES', 7 => '[email protected]|TD-About Me #1004|YES', 8 => '[email protected]|TD-Calendar #1007|YES', 9 => '[email protected]|TD-Wage Tracker #1008|YES', 10 => '[email protected]|TD-Stock Portfolio #1009|YES', 11 => '[email protected]|TD-Collaboration #1005|YES', 12 => '[email protected]|TD-Stock Portfolio #1009|YES', 13 => '[email protected]|TD-Collaboration #1005|YES', 14 => '[email protected]|TD-Dream Vacation Presentation #1015|YES', );

$combinedAssignmentData = []; 
foreach($assignmentsYES as $key=>$level){
    $combinedAssignmentData[$level] = preg_grep('/#'.$level.'\|/', $studentIDsubmissions);
}

print_r($combinedAssignmentData);

Using Preg Grep is a bit cleaner then array filter and a callback with a regular expression. I also realized you had a superficial loop in there $levels = array($assignedIDs); or basically $levels = array($level); or just $level.

Same output as before

Sandbox

thanks for your help with this! You solution worked, but I realized I need a slight change and I'm hoping you can help. Your solution created an "Associative Arrays", but I need it to be an "Indexed Array". Can You please update your solution so it creates an "Indexed Array" in the same structure? Thanks again!
If you can show me an example (preferably as an update to the question) of what the expected output is, I can update it. it creates an "Indexed Array" in the same structure You can just do array_values($combinedAssignmentData) to remove the keys, or change this line $combinedAssignmentData[$level] = preg_grep(...) to $combinedAssignmentData[] = preg_grep(...) That said the keys are very useful, and easy to work around. For example want to know if there are items in a given ID count($combinedAssignmentData[$id]) - Think without the ID how will you find it....
Thanks for the info! I'll work on this later today. Also, I appreciate extra insight you offer in your solutions and comments. They really help someone learning the language and concepts better understand a solution.

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