$numbers = array(1,3,2,4,5,6,7,8,9,11,10,15,14,13,12,16,17,18,19,20,22);

function get_number_ranges($numbers)
{
    $last = null;
    foreach ($numbers as $number) {
        if (is_null($last)) {
            $string = $number;
            $last = $number;
        } elseif ($last + 1 != $number) {
            $string .= '-' . $last . ', ' . $number;
            $last = $number;
        } else {
            $last = $number;
        }
    }

    if ($last == $number) {
        $string .= '-' . $number;
    }

    return $string;
}

1-1, 3-3, 2-2, 4-9, 11-11, 10-10, 15-15, 14-14, 13-13, 12-12, 16-20, 22-22

1, 3, 2, 4-9, 11, 10, 15, 14, 13, 12, 16-20, 22

function get_number_ranges($numbers)
{
    $last = null;
    foreach ($numbers as $number) {
        if (is_null($last)) {
            $string = $number;
            $last = $number;
            $first = $number ;                          //Remember first
        } elseif ($last + 1 != $number) {
            if ($first != $last )                       //Only append if different
                $string .= '-' . $last ;
            $string .= ', ' . $number;
            $last = $number;
            $first = $number ;                          //Remember first
        } else {
            $last = $number;
        }
    }

    if ($last == $number && $last != $first) {          //Only if different
        $string .= '-' . $number;
    }

    return $string;
}

$numbers = array(1,3,2,4,5,6,7,8,9,11,10,15,14,13,12,16,17,18,19,20,22);

function get_number_ranges($numbers)
{
    $last = null;
    $firstFromRange = null;
    foreach ($numbers as $number) {
        if (is_null($last)) {
            $string = $number;
            $firstFromRange = $number; // new range begins, save the number
        } elseif ($last + 1 != $number) {
            if ($firstFromRange == $last) { // if the range is only one number, don't add '-' . $last
                $string .= ', ' . $number;
            } else {
                $string .= '-' . $last . ', ' . $number;
            }
            $firstFromRange = $number; // new range begins, save the number
        }

        $last = $number;
    }

    if ($last == $number && $last != $firstFromRange) {
        $string .= '-' . $number;
    }

    return $string;
}

<?php
$numbers = array(1,3,2,4,5,6,7,8,9,11,10,15,14,13,12,16,17,18,19,20,22);

function get_number_ranges($numbers){
    $result = '';
    if( is_array($numbers) ){
        $start = $end = array_shift($numbers);
        for($i=0,$c=count($numbers);$i<$c;$i++){
            if($end == $numbers[$i]-1){
                $end = $numbers[$i];
            }else{
                $result .= ($start == $end) ? $start: $start.'-'.$end;
                $result .= ',';
                $start = $end = $numbers[$i];
            }
        }
        $result .= ($start == $end) ? $start: $start.'-'.$end;
    }

    return $result;
}

echo get_number_ranges($numbers );