Foreach code working - but asking for optimalization - php

Question

The below code works and does output exactly what i want. I made a foreach loop getting the values of a specific field ($CustomFields...) which is part of a framework variable. Then is only counts that field when the condition is "group".
After that i want to het the average price of all fields / count.
// ########### Get average hourly rate for group classes
$itemsperhour = array();
$countperhour = 0;
foreach($listings as $listing) {
if ($CustomFields->fieldValue('jr_typeoflesson',$listing,false,false) == 'group') {
$itemsperhour[] = $CustomFields->field('jr_hourlyrateus',$listing,false,false);
$countperhour = $countperhour + 1;
}
}
//print_r($items);
if ($countperhour > 0) {
$totalperhour = array_sum($itemsperhour);
$averageperhour =($totalperhour / $countperhour);
echo round($averageperhour,2);
} else {
echo "No data";
}
unset ($averageperhour);
As said, the snippet works. But may I ask how other people would write such a script related to optimise such a piece of code (for speed and readability?
PHP 5.6+
Jasper

Answer 1

Below is one way of optimizing:
$totalperhour = 0;
$countperhour = 0;
foreach($listings as $listing) {
if ($CustomFields->fieldValue('jr_typeoflesson',$listing,false,false) == 'group') {
$totalperhour += $CustomFields->field('jr_hourlyrateus',$listing,false,false);
$countperhour = $countperhour + 1;
}
}
if($countperhour > 0) {
$averageperhour =($totalperhour / $countperhour);
echo round($averageperhour,2);
$averageperhour = '';
} else {
echo "No data";
}

Answer 2

I would suppose to use array_reduce function for getting the average:
$averageperhour = array_reduce($listings, function($average, $listing) use (&$CustomFields)
{
static $sum = 0;
static $counter = 0;
if ($CustomFields->fieldValue('jr_typeoflesson', $listing, false, false) == 'group') {
$sum += $CustomFields->field('jr_hourlyrateus', $listing, false, false);
$counter ++;
$average = round(($sum / $counter), 2);
}
return $average;
}, 'No data');
echo $averageperhour;
Not sure about speed improvement (needs testing), but this variant seems to me like more readable.

Answer 3

How about this?
$itemsPerHour = [];
foreach($listings as $listing) {
if ($CustomFields->fieldValue('jr_typeoflesson', $listing, false, false) !== 'group') {
continue;
}
$itemsPerHour[] = $CustomFields->field('jr_hourlyrateus', $listing, false, false);
}
$countPerHour = count($itemsPerHour);
if ($countPerHour > 0) {
$averagePerHour = array_sum($itemsPerHour) / $countPerHour;
echo round($averagePerHour,2);
} else {
echo "No data";
}