Function to get element in array, that goes previous your key or false if it not exeists or key doesn't isset in array.
<?php
function previousElement(array $array, $currentKey)
{
if (!isset($array[$currentKey])) {
return false;
}
end($array);
do {
$key = array_search(current($array), $array);
$previousElement = prev($array);
}
while ($key != $currentKey);
return $previousElement;
}