phparraysgroupingcounting

Group and count streaks of repeated values in a flat array

I need to count the "streaks" of repeated values in a flat array.

Sample input array:

['A', 'A', 'B', 'B', 'C', 'A', 'A']

I need an array like:

array(
    'A' => (count1 => 2, count2 => 2),
    'B' => (count1 => 2),
    'C' => (count1 => 1)
)
Solution 
  • $data = array(0=>A,1=>A,2=>B,3=>B,4=>C,5=>A,6=>A);

$counters = array();
$prev = NULL;
array_walk(
    $data,
    function ($entry) use (&$prev, &$counters) {
        if ($entry !== $prev) {
            $prev = $entry;
            $counters[] = 1;
        } else {
            $counters[count($counters)-1]++;
        }
    }
);
var_dump($counters);