粗略的問了大神.可是卻沒發現相類似的PHP版本
所以只好花了點時間來將 Ruby 版本轉了一下
另外還將相對應的 confidence sort 也轉了過來..
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| <?php
date_default_timezone_set("Asia/Hong_Kong");
function calculate_rank_sum($score, $created_at) {
$order = log10(max(abs($score), 1));
if ($score > 0) {
$sign = 1;
}elseif ($score < 0) {
$sign = -1;
}else{
$sign = 0;
}
$seconds = intval(($created_at - mktime(0, 0, 0, 1, 1, 1970))/86400);
$long_number = $order + $sign * $seconds / 45000;
return round($long_number, 7);
}
function confidence($ups, $downs) {
if ($ups + $downs == 0) {
return 0;
}else{
$n = $ups + $downs;
if ($n == 0) return 0;
$z = 1.0;
$phat = (float)$ups / $n;
return sqrt($phat+$z*$z/(2*$n)-$z*(($phat*(1-$phat)+$z*$z/(4*$n))/$n))/(1+$z*$z/$n);
}
}
echo calculate_rank_sum(10, time()), "\n";
echo confidence(10, 0), "\n";
?>
|
參考:
http://stackoverflow.com/questions/5365525/why-is-my-rank-sum-database-column-still-nil
http://amix.dk/blog/post/19588
