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<?php | |
/** | |
* Return the coefficient of two items based on Jaccard index | |
* http://en.wikipedia.org/wiki/Jaccard_index | |
* | |
* Example: | |
* | |
* $tags1 = "code, php, jaccard, test, items"; | |
* $tags2 = "test, code"; | |
* echo getSimilarityCoefficient( $tags1, $tags2 ); // 0.28 | |
* | |
* $str1 = "similarity coefficient of two items"; | |
* $str2 = "two items are cool"; | |
* echo getSimilarityCoefficient( $str1, $str2, " " ); // 0.44 | |
* | |
* @param string $item1 | |
* @param string $item2 | |
* @param string $separator | |
* @return float | |
* @author Henrique Hohmann | |
* @version 0.1 | |
*/ | |
function getSimilarityCoefficient( $item1, $item2, $separator = "," ) { | |
$item1 = explode( $separator, $item1 ); | |
$item2 = explode( $separator, $item2 ); | |
$arr_intersection = array_intersect( $item2, $item2 ); | |
$arr_union = array_merge( $item1, $item2 ); | |
$coefficient = count( $arr_intersection ) / count( $arr_union ); | |
return $coefficient; | |
} | |
?> |
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array_intersect will return duplicates if they are present in the first array, so the results may be wrong:
change line 28 to: