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recommend.php
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recommend.php
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<?php
function similarity_distance($matrix,$person1,$person2)
{
$similar=array();
$sum=0;
foreach($matrix[$person1] as $key=>$value)
{
if(array_key_exists($key,$matrix[$person2])){
$similar[$key]=1;
}
}
if($similar==0){
return 0;
}
foreach($matrix[$person1] as $key=>$value)
{
if(array_key_exists($key,$matrix[$person2])){
$sum=$sum+pow($value-$matrix[$person2][$key],2);
}
}
return 1/(1+sqrt($sum));
}
function getRecommendation($matrix, $person){
$total=array();
$simsums=array();
$ranks=array();
foreach($matrix as $otherPerson=>$value){
if($otherPerson!=$person){
$sim=similarity_distance($matrix,$person,$otherPerson);
foreach($matrix[$otherPerson] as $key=>$value){
if(!array_key_exists($key,$matrix[$person])){
if(!array_key_exists($key,$total))
{
$total[$key]=0;
}
$total[$key]+=$matrix[$otherPerson][$key]*$sim;
if(!array_key_exists($key,$simsums))
{
$simsums[$key]=0;
}
$simsums[$key]+=$sim;
}
}
}
}
foreach($total as $key=>$value){
$ranks[$key]=$value/$simsums[$key];
}
array_multisort($ranks,SORT_DESC);
return $ranks;
}
?>