在 php中有这样的 java 实现吗？
<?php
/**
* Returns conditional probability of $A given $B and $Data.
* $Data is an indexed array. Each element of the $Data array
* consists of an A measurement and B measurment on a sample
* item.
*/
function getConditionalProbabilty($A, $B, $Data) {
$NumAB = 0;
$NumB = 0;
$NumData = count($Data);
for ($i=0; $i < $NumData; $i++) {
if (in_array($B, $Data[$i])) {
$NumB++;
if (in_array($A, $Data[$i])) {
$NumAB++;
}
}
}
return $NumAB / $NumB;
}
?>
<?php
require "getConditionalProbability.php";
/**
* The elements of the $Data array use this coding convention:
*
* +cancer - patient has cancer
* -cancer - patient does not have cancer
* +test - patient tested positive on cancer test
* -test - patient tested negative on cancer test
*/
$Data[0] = array("+cancer", "+test");
$Data[1] = array("-cancer", "-test");
$Data[2] = array("+cancer", "+test");
$Data[3] = array("-cancer", "+test");
// specify query variable $A and conditioning variable $B
$A = "+cancer";
$B = "+test";
// compute the conditional probability of having cancer given 1)
// a positive test and 2) a sample of covariation data
$probability = getConditionalProbabilty($A, $B, $Data);
echo "P($A|$B) = $probability";
// P(+cancer|+test) = 0.66666666666667
?>