CyberChef/src/core/operations/ChiSquare.mjs

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2018-05-16 12:39:30 +02:00
/**
* @author n1474335 [n1474335@gmail.com]
* @copyright Crown Copyright 2017
* @license Apache-2.0
*/
import Operation from "../Operation";
/**
* Chi Square operation
*/
class ChiSquare extends Operation {
/**
* ChiSquare constructor
*/
constructor() {
super();
this.name = "Chi Square";
this.module = "Default";
this.description = "Calculates the Chi Square distribution of values.";
this.infoURL = "https://wikipedia.org/wiki/Chi-squared_distribution";
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this.inputType = "ArrayBuffer";
this.outputType = "number";
this.args = [];
}
/**
* @param {ArrayBuffer} input
* @param {Object[]} args
* @returns {number}
*/
run(input, args) {
const data = new Uint8Array(input);
const distArray = new Array(256).fill(0);
let total = 0;
for (let i = 0; i < data.length; i++) {
distArray[data[i]]++;
}
for (let i = 0; i < distArray.length; i++) {
if (distArray[i] > 0) {
total += Math.pow(distArray[i] - data.length / 256, 2) / (data.length / 256);
}
}
return total;
}
}
export default ChiSquare;