php get correlation coefficient

Friendly Hawk answered on August 1, 2022 Popularity 3/10 Helpfulness 10/10

answer php get correlation coefficient

php get correlation coefficient

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//get pearsons correlation coeficient
function pearsons_correlation($x,$y){
    if(count($x)!==count($y)){return -1;}   
    $x=array_values($x);
    $y=array_values($y);    
    $xs=array_sum($x)/count($x);
    $ys=array_sum($y)/count($y);    
    $a=0;$bx=0;$by=0;
    for($i=0;$i<count($x);$i++){     
        $xr=$x[$i]-$xs;
        $yr=$y[$i]-$ys;     
        $a+=$xr*$yr;        
        $bx+=pow($xr,2);
        $by+=pow($yr,2);
    }   
    $b = sqrt($bx*$by);
    if($b==0) return 0;
    return $a/$b;
}

echo pearsons_correlation(array(1, 3, 7), array(1, 4, 9));//0.99890610723867

Popularity 3/10 Helpfulness 10/10 Language php

Source: stackoverflow.com

Tags: correlation get php

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