Delete all of todays files in folder except for file dated closest to 12 noon

[waubain]

I have a webcam that uploads an image every hour to a folder on a server. At the end of the day I want to delete all the images except for the image with datetime closest to 12 noon, which I keep for historical use.

This part works and finds the closest image to 12 noon and puts them in an array sorted by the difference in seconds.

<?php
date_default_timezone_set("America/Chicago");
$today = new DateTime();
$startday = $today->setTime(0,1);
$startday = $startday->getTimestamp();
$tnoon = $today->setTime(12,0);
$tnoon = $tnoon->getTimestamp();

$diff = array();
$dir = "camgallery";
$fileSystemIterator = new FilesystemIterator($dir);

/* create array containing datediff and filename */
foreach ($fileSystemIterator as $fileInfo) {
    if ($fileInfo->isFile() && $fileInfo->getCTime() >= $startday) {
        $seconds = abs($tnoon - $fileInfo->getCTime());
        $diff[] = ['timediff' => $seconds,
        'filename' => $fileInfo->getFilename()
        ];
    }
}
/*sort array by seconds */
array_multisort(array_column($diff, 'timediff'), SORT_ASC, $diff);

?>

What I cannot figure out is how to delete all the files except for the file with the lowest seconds, which should be the first element in the array.

/*delete all files except for first file in array  */
    for ($i = 1; $i < count($diff); $i++) {
        unlink($dir . "/" . [$i]['filename']); 
    }

If there is a better way, I am open to learning.
Thanks in advance.

 

[waubain]

This works, but I am not sure it is the best method.

/* delete all files except file with index 0 */
    for ($i = 1; $i < count($diff); $i++) {
        unlink($dir . "/" . $diff[$i]['filename']);
        }