stats_stat_correlation

(PECL stats >= 1.0.0)

stats_stat_correlationNot documented

Description

float stats_stat_correlation ( array $arr1 , array $arr2 )
Warning

This function is currently not documented; only its argument list is available.

Parameters

arr1

arr2

Return Values

Коментарии

I tried to use this function, but got a not-defined error. Anyway, I have created a set of functions to replace this: 

<?php

//Since Correlation needs two arrays, I am hardcoding them
$array1[0] = 59.3;
$array1[1] = 61.2;
$array1[2] = 56.8
$array1
[3] = 97.55;

$array2[0] = 565.82;
$array2[1] = 54.568;
$array2[2] = 84.22;
$array2[3] = 483.55;

//To find the correlation of the two arrays, simply call the 
//function Correlation that takes two arrays:

$correlation Correlation($array1$array2);

//Displaying the calculated Correlation:
print $correlation;

//The functions that work behind the scene to calculate the
//correlation

function Correlation($arr1$arr2)
{       
   
$correlation 0;
   
   
$k SumProductMeanDeviation($arr1$arr2);
   
$ssmd1 SumSquareMeanDeviation($arr1);
   
$ssmd2 SumSquareMeanDeviation($arr2);
   
   
$product $ssmd1 $ssmd2;
   
   
$res sqrt($product);
   
   
$correlation $k $res;
   
    return 
$correlation;
}

function 
SumProductMeanDeviation($arr1$arr2)
{
   
$sum 0;
   
   
$num count($arr1);
   
    for(
$i=0$i<$num$i++)
    {
       
$sum $sum ProductMeanDeviation($arr1$arr2$i);
    }
   
    return 
$sum;
}

function 
ProductMeanDeviation($arr1$arr2$item)
{
    return (
MeanDeviation($arr1$item) * MeanDeviation($arr2$item));
}

function 
SumSquareMeanDeviation($arr)
{
   
$sum 0;
   
   
$num count($arr);
   
    for(
$i=0$i<$num$i++)
    {
       
$sum $sum SquareMeanDeviation($arr$i);
    }
   
    return 
$sum;
}

function 
SquareMeanDeviation($arr$item)
{
    return 
MeanDeviation($arr$item) * MeanDeviation($arr$item);
}

function 
SumMeanDeviation($arr)
{
   
$sum 0;
   
   
$num count($arr);
   
    for(
$i=0$i<$num$i++)
    {
       
$sum $sum MeanDeviation($arr$i);
    }
   
    return 
$sum;
}

function 
MeanDeviation($arr$item)
{
   
$average Average($arr);
   
    return 
$arr[$item] - $average;
}   

function 
Average($arr)
{
   
$sum Sum($arr);
   
$num count($arr);
   
    return 
$sum/$num;
}

function 
Sum($arr)
{
    return 
array_sum($arr);
}

?>
2009-03-05 00:05:51
http://php5.kiev.ua/manual/ru/function.stats-stat-correlation.html
Please note that this function is reserved for two arrays with continued numbers inside (just integers).
I tested this function and found that it calculate the Pearson's Correlation Coefficient of two arrays.
---
Here's suggested documentation:

stats_stat_correlation — Calculate the Pearson's Correlation Coefficient of two arrays of continued numbers.

Parameters:
arr1 = array (integer1a, interger2a ...)
arr2 = array (integer1b, interger2b ...))
(Note that the count of elements in two arrays must be equal)

Return value: Pearson's Correlation Coefficient in decimal format (ex. 0.934399822094)

Code examples:

<?php
// Provided by admin@maychu.net
$array_x = array(5,3,6,7,4,2,9,5);
$array_y = array(4,3,4,8,3,2,10,5);
$pearson stats_stat_correlation($array_x,$array_y);
echo 
$pearson;
?>
2009-06-15 00:58:44
http://php5.kiev.ua/manual/ru/function.stats-stat-correlation.html
Автор:
undefined for me, thus I've implemented my own correlation which is much faster and simpler than the one provided above.

function Corr($x, $y){

$length= count($x);
$mean1=array_sum($x) / $length;
$mean2=array_sum($y) / $length;

$a=0;
$b=0;
$axb=0;
$a2=0;
$b2=0;

for($i=0;$i<$length;$i++)
{
$a=$x[$i]-$mean1;
$b=$y[$i]-$mean2;
$axb=$axb+($a*$b);
$a2=$a2+ pow($a,2);
$b2=$b2+ pow($b,2);
}

$corr= $axb / sqrt($a2*$b2);

return $corr;
}
2015-01-19 13:30:40
http://php5.kiev.ua/manual/ru/function.stats-stat-correlation.html

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