Collections: add arg for formatting decimal point

[hiro-lapis]

In current, Collections avg() is like this. It`s alway return native float value,

$points = [3, 3, 6, 7, 2, 5];
$result = collect($points)->avg();
echo $result;// 4.3333333333333

Sometimes we want formatted value, need format out of this method.
I think It would be better to include format process in avg(), in a view of encapsuling get average process.

So My suggestion of implementation:

public function avg($callback = null, $format = null)
{
    $callback = $this->valueRetriever($callback);

    $items = $this->map(function ($value) use ($callback) {
        return $callback($value);
    })->filter(function ($value) {
        return ! is_null($value);
    });

    if ($count = $items->count()) {
        return $format ? $format($items->sum() / $count) : $items->sum() / $count;
    }
}

sample spec of suggestion

$points = [3, 3, 6, 7, 2, 5];
$my_format_round = fn ($arg)=> round($arg, 1);
echo  collect($points)->avg(null, $my_format_round); // 4.3

$my_format_ceil = fn ($arg)=> ceil($arg);
echo  collect($points)->avg(null, $my_format_ceil); // 5

$my_format_floor = fn ($arg)=> floor($arg);
echo  collect($points)->avg(null, $my_format_floor); // 5

[parallels999]

Why don't just

$points = [3, 3, 6, 7, 2, 5];
echo  round(collect($points)->avg(), 1); // 4.3
echo  ceil(collect($points)->avg()); // 5
echo  floor(($points)->avg()); // 5