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ngopal/ConfusionMatrix.js

Last active August 29, 2015 14:03
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A small javascript library to create a confusion matrix and calculate values of true positives, true negatives, false positives, false negatives, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood, negative likelihood, prevalence, false positive rate, false discovery rate, false negative rate, Mat…
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ConfusionMatrix.js
// Written by Nikhil Gopal
// http://www.nikhilgopal.com
function TwoCellCalculation(k,j) {
return(k/(k+j));
}
function ConfusionMatrix(a,b,c,d) {
this.n = a+b+c+d;
this.true_positives = a;
this.false_positives = b;
this.false_negatives = c;
this.true_negatives = d;
this.sensitivity = TwoCellCalculation(a,c);
this.specificity = TwoCellCalculation(b,d);
this.ppv = TwoCellCalculation(a,b);
this.npv = TwoCellCalculation(c,d);
this.positive_likelihood = this.sensitivity / (1-this.specificity);
this.negative_likelihood = 1/this.positive_likelihood;
this.prevalence = (a+c)/(a+b+c+d);
this.fpr = 1 - this.specificity;
this.fdr = 1 - this.ppv;
this.fnr = this.false_negatives / (this.false_negatives+this.true_positives);
this.mcc = ((this.true_positives*this.true_negatives)-(this.false_positives*this.false_negatives))/Math.sqrt((this.true_positives+this.false_positives)*(this.true_positives+this.false_negatives)*(this.true_negatives+this.false_positives)*(this.true_negatives+this.false_negatives));
this.acc = (this.true_positives+this.true_negatives)/this.n;
this.f1 = 2*(this.true_positives)/(2*this.true_positives+this.false_positives+this.false_negatives);
this.informedness = this.sensitivity+this.specificity-1;
this.markedness = this.ppv + this.npv - 1;
return(this);
}
var A = ConfusionMatrix(400,430,230,740);
$('sensitivity').html( A.ppv );
Raw
index.html
<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script src="ConfusionMatrix.js"></script>
<meta charset="utf-8">
<title>Confusion Matrix</title>
</head>
<body>
<sensitivity></sensitivity>
<a href="http://en.wikipedia.org/wiki/Sensitivity_and_specificity">More info</a>
</body>
</html>
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