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MDL-13124 : simplify and fix the tag correlation logic.

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scyrma 2008-01-24 08:39:38 +00:00
parent fdece1bf70
commit c0491d4aca
1 changed files with 6 additions and 6 deletions
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12
tag/lib.php
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@ -835,7 +835,7 @@ function update_tag_correlations($item_type, $item_id) {
* @param number $min_correlation cutoff percentage (optional, default is 0.25)
* @param int $limitnum return a subset comprising this many records (optional, default is 10)
*/
function cache_correlated_tags($tag_name_or_id, $min_correlation=0.25, $limitnum=10) {
function cache_correlated_tags($tag_name_or_id, $min_correlation=2, $limitnum=10) {
global $CFG;
$tag_id = tag_id_from_string($tag_name_or_id);
@ -845,17 +845,17 @@ function cache_correlated_tags($tag_name_or_id, $min_correlation=0.25, $limitnum
$query = "SELECT tb.tagid , COUNT(*) nr
FROM {$CFG->prefix}tag_instance ta
INNER JOIN {$CFG->prefix}tag_instance tb ON ta.itemid = tb.itemid
WHERE ta.tagid = {$tag_id}
WHERE ta.tagid = {$tag_id} AND tb.tagid != {$tag_id}
GROUP BY tb.tagid
ORDER BY nr DESC";
$correlated = array();
if ($tag_correlations = get_records_sql($query, 0, $limitnum)) {
$cutoff = $tag_correlations[$tag_id]->nr * $min_correlation;
// Correlated tags happen when they appear together in more occasions
// than $min_correlation.
if ($tag_correlations = get_records_sql($query, 0, 10)) {
foreach($tag_correlations as $correlation) {
if($correlation->nr >= $cutoff && $correlation->tagid != $tag_id ){
if($correlation->nr >= $min_correlation){
$correlated[] = $correlation->tagid;
}
}