@neutrium/quantity/dist/operations/unit-signatures.js

The NeutriumJS unit conversion module.

import { UnitTokenManager } from "../UnitTokenManager.js";
//
// Calculates the unit signature id for use in comparing compatible units and simplification
// the signature is based on a simple classification of units and is based on the following publication
//
// Novak, G.S., Jr. "Conversion of units of measurement", IEEE Transactions on Software Engineering,
// 21(8), Aug 1995, pp.651-661
// doi://10.1109/32.403789
// http://www.cs.utexas.edu/~novak/units95.html
//
export function unitSignature(a) {
    if (a.signature) {
        return a.signature;
    }
    let vector = unitSignatureVector(a);
    for (let i = 0, len = vector.length; i < len; i++) {
        vector[i] *= Math.pow(20, i); // Not sure if equation is correct
    }
    return vector.reduce(function (previous, current) { return previous + current; }, 0);
}
;
// calculates the unit signature vector used by unit_signature
function unitSignatureVector(a) {
    const tokenMapper = UnitTokenManager.instance;
    const SIGNATURE_VECTOR = ["length", "time", "temperature", "mass", "current", "substance", "luminosity", "currency", "data", "angle", "capacitance"];
    if (!a.isBase()) {
        return unitSignatureVector(a.toBase());
    }
    let vector = new Array(SIGNATURE_VECTOR.length), r, n;
    for (let i = 0; i < vector.length; i++) {
        vector[i] = 0;
    }
    // Numerator - ["<kilogram>","<meter>"]
    for (let j = 0, len = a.numerator.length; j < len; j++) {
        if ((r = tokenMapper.getUnit(a.numerator[j]))) {
            n = SIGNATURE_VECTOR.indexOf(r.category);
            if (n >= 0) {
                vector[n] = vector[n] + 1;
            }
        }
    }
    for (let k = 0, len = a.denominator.length; k < len; k++) {
        if ((r = tokenMapper.getUnit(a.denominator[k]))) {
            n = SIGNATURE_VECTOR.indexOf(r.category);
            if (n >= 0) {
                vector[n] = vector[n] - 1;
            }
        }
    }
    return vector;
}
;