How to split an array based on a certain value?

Question

I currently have an array of location based information similar to below (which is already sorted by time). The first key/value is event which represents the start of a journey (00), a running journey (01) and an end of a journey (10).

Array ( 
[0] => Array ( [event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[1] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[2] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[3] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[4] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[5] => Array ( [event] => 10 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[6] => Array ( [event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[7] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[8] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[9] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[10] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[11] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[12] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[13] => Array ( [event] => 10 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[14] => Array ( [event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[15] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[16] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[17] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[18] => Array ( [event] => 10 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
)

How can I split the array even further so it creates a new array for every journey so I would end up with this:

Array (
[0] => Array (
[0] => Array ( [event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[1] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[2] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[3] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[4] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[5] => Array ( [event] => 10 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
)
[1] => Array (
[0] => Array ( [event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[1] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[2] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[3] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[4] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[5] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[6] => Array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
[7] => Array ( [event] => 10 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 )
)
...
)

I haven't tried anything yet (except for googling) as I don't really know where to start.

hackartist · Accepted Answer · 2012-02-20 00:54:15Z

2

you need a custom solution like so:

 $outputArray = array(); $currentArray = array();
 foreach($inputArray as $key=>$subArray) {
   if($subArray['event']==00) {
      $outputArray[] = $currentArray;
      $currentArray = array($subArray);
   } else {
      $currentArray[] = $subArray;
   }
 }
 $outputArray[] = $currentArray;
 array_shift($outputArray);

put in $inputArray and then get out $outputArray. Enjoy!

edited Feb 20, 2012 at 0:54

answered Feb 20, 2012 at 0:19

hackartist

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2 Comments

7wonders Over a year ago

It almost works. Seems to miss the last one off though. - $outputArray array (3) array(0) array (6) array (8)

hackartist Over a year ago

you are correct... try the new edit and it should work. Srry about that.

Christopher Pelayo · Accepted Answer · 2012-02-20 00:33:34Z

try this:

this code should create an array structure like:

array(
[00] => array([0] => array([event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111) [1]=>array ( [event] => 00 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111 ))
[01] => array([0]=>array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111) [1]=>array ( [event] => 01 [time] => 1329293878 [lat] => 66.66666 [lon] => 11.11111)  )
);

and so on...

But this creates a grouped array based on the event and not each journey? Or am I missing something? $journeygrouping array (3) '10' => array (3) '1' => array (13) '0' => array (3)

mickmackusa · Accepted Answer · 2024-06-25 22:59:42Z

For a clean script that will produce an empty result array from an empty input array, avoid processes outside of a loop construct. @hackartist's answer will create a non-empty array from an empty input array. To avoid mutating the input array, do not consume elements by calling array_pop() as in @Christopher Pelayo's answer.

I'll recommend pushing reference variables into the result array ONLY if there are elements in the input array and pushing set-related elements into the reference variable. This way you don't need to track the position of the current group in the result array.

Code: (Demo)

$result = [];
foreach ($array as $row) {
    if ($row['event'] === '00') {
        unset($ref);
        $result[] =& $ref;
    }
    $ref[] = $row;
}
var_export($result);

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