Calculate coefficient of relationship in javascript

coefficientOfRelationship.js

// Used to calculate Coefficient of relationship
// https://en.wikipedia.org/wiki/Coefficient_of_relationship

// Limitations: Does not handle identical twin common ancestors

// Test examples based on http://www.genetic-genealogy.co.uk/Toc115570135.html

var init = function (persons) {
	for (p in persons) {
	    	persons[p].children = [];
	}

	// Add reversed relationship
	for (p in persons) {
		const o = persons[p];
		if (o.mother) {
			o.mother.children.push(o);
		}
		if (o.father) {
			o.father.children.push(o);
	    	}
	}
}

// Find distinct paths from p to ancestors
var findPaths = function(_acc, p) {
	if (!p) {
		return [];
	}   

	// Create a new object since javascript uses references as default
	const acc = _acc.slice();

	acc.push(p.name);

	return [acc].concat(findPaths(acc, p.mother)).concat(findPaths(acc, p.father)); 
}

// Check if an array has duplicates
var hasDuplicates = function (arr) {
	return new Set(arr).size !== arr.length;
}

// Find all paths through ancestors between a and b
var findAncestorPaths = function(a, b) {
	var result = [];
	var aPaths = findPaths([], a);
	var bPaths = findPaths([], b);

	if (aPaths.length > 1 && bPaths.length > 1) {
		for (const i in aPaths) {
			// Choose a node to check as common ancestor
			const nodeToCheck = aPaths[i].slice(-1)[0];

			for (const j in bPaths) {
				// Find a path which shares the same end node (to test for common ancestor)
				if (nodeToCheck == bPaths[j].slice(-1)[0]) {
					const aPath = aPaths[i].slice(0,-1);
					const bPath = bPaths[j].slice(0,-1);

					console.log('Testing ' + aPaths[i] + ', ' + bPaths[j])
					
					// Make sure the paths doesn't share any nodes except last/ancestor
					if (!hasDuplicates(aPath.concat(bPath))) {
						console.log('Found match: ' + aPaths[i] + ' - ' + bPaths[j]);
						result.push(aPath.concat(bPaths[j]));
					}
				}
			}
		}
	} else {
		// In case one of the nodes is a root node
		var nodeToCheck;
		var paths;

		if (aPaths.length == 0) {
			nodeToCheck = a.name;
			paths = bPaths;
		} else {
			nodeToCheck = b.name;
			paths = aPaths;
		}

		for (i in paths) {
			const path = paths[i];
			if (nodeToCheck == path.slice(-1)[0]) {
				console.log('Found match: ' + path + ', ' + nodeToCheck);
				result.push(path);
			}
		}
	}

	return result;
}

var coefficientOfRelationship = function(a, b) {
	console.log("\n");
	var paths = findAncestorPaths(a, b);
	var sum = 0;

	console.log("\n");

	for (const i in paths) {
		const path = paths[i];

		// Generations between a and b
		const n = path.length - 1;

		// Coefficients of inbreeding, default 1.0
		const fa = a.f || 1.0;
		const fo = b.f || 1.0;

		const result = Math.pow(2, -n)*Math.pow((1+fa)/(1+fo), 1/2);
		sum += result;

		console.log("Calculating coefficient for n=" + n, "a=" + a.name, "b=" + b.name, "fa=" + fa, "fo=" + fo, "path=" + path, "result=" + result, "sum=" + sum);		
	}

	return sum;
}

// = 0.0625
var testFigure8 = function() {
	console.log('\n\n=== Running test figure 8 ===');
	const a = {name: 'a', f: 1.0};
	const b = {name: 'b', f: 1.0};
	const c = {name: 'c', f: 1.0};
	const d = {name: 'd', f: 1.0};
	const e = {name: 'e', f: 1.0};
	const f = {name: 'f', f: 1.0};
	const g = {name: 'g', f: 1.0};
	const h = {name: 'h', f: 1.0};
	const i = {name: 'i', f: 1.0};

	i.mother=g;
	i.father=h;
	g.mother=e;
	g.father=f;
	e.mother=c;
	e.father=d;
	c.mother=a;
	c.father=b;
	
	const persons = [a, b, c, d, e, f, g, h, i];

	init(persons);
	return coefficientOfRelationship(i, a);
}

// = 0.125
var testFigure9 = function() {
	console.log('\n\n=== Running test figure 9 ===');
	const a = {name: 'a', f: 1.0};
	const b = {name: 'b', f: 1.0};
	const c = {name: 'c', f: 1.0};
	const d = {name: 'd', f: 1.0};
	const e = {name: 'e', f: 1.0};
	const f = {name: 'f', f: 1.0};
	const g = {name: 'g', f: 1.0};
	const h = {name: 'h', f: 1.0};
	const i = {name: 'i', f: 1.0};
	const j = {name: 'j', f: 1.0};
	const k = {name: 'k', f: 1.0};
	const l = {name: 'l', f: 1.0};
	const m = {name: 'm', f: 1.0};

	m.mother=k;
	m.father=l;
	k.mother=g;
	k.father=h;
	l.mother=i;
	l.father=j;
	h.mother=c;
	h.father=d;
	i.mother=e;
	i.father=f;
	d.mother=a;
	d.father=b;
	e.mother=a;
	e.father=b;
	
	const persons = [a, b, c, d, e, f, g, h, i, j, k, l, m];

	init(persons);
	return coefficientOfRelationship(m, a);
}

// = 0.125
var testFigure10 = function() {
	console.log('\n\n=== Running test figure 10 ===');
	const a = {name: 'a', f: 1.0};
	const b = {name: 'b', f: 1.0};
	const c = {name: 'c', f: 1.0};
	const d = {name: 'd', f: 1.0};
	const e = {name: 'e', f: 1.0};
	const f = {name: 'f', f: 1.0};
	const g = {name: 'g', f: 1.0};
	const h = {name: 'h', f: 1.0};

	g.mother=c;
	g.father=d;
	h.mother=e;
	h.father=f;
	d.mother=a;
	d.father=b;
	e.mother=a;
	e.father=b;
	
	const persons = [a, b, c, d, e, f, g, h];

	init(persons);
	return coefficientOfRelationship(g, h);
}

// = 0.5625
var testFigure11 = function() {
	console.log('\n\n=== Running test figure 11 ===');
	const a = {name: 'a', f: 1.0};
	const b = {name: 'b', f: 1.0};
	const c = {name: 'c', f: 1.0};
	const d = {name: 'd', f: 1.0};
	const e = {name: 'e', f: 1.0};
	const f = {name: 'f', f: 1.0};
	const g = {name: 'g', f: 1.0};
	const h = {name: 'h', f: 1.0};
	const i = {name: 'i', f: 1.0};
	const j = {name: 'j', f: 1.0}; 

	i.mother=g;
	i.father=h;
	j.mother=g;
	j.father=h;
	g.mother=c;
	g.father=d;
	h.mother=e;
	h.father=f;
	d.mother=a;
	d.father=b;
	e.mother=a;
	e.father=b;

	const persons = [a, b, c, d, e, f, g, h, i, j];

	init(persons);
	return coefficientOfRelationship(i, j);
}

// = 0.1875
var testFigure12 = function() {
	console.log('\n\n=== Running test figure 12 ===');
	const a = {name: 'a', f: 1.0};
	const b = {name: 'b', f: 1.0};
	const c = {name: 'c', f: 1.0};
	const d = {name: 'd', f: 1.0};
	const e = {name: 'e', f: 1.0};
	const f = {name: 'f', f: 1.0};
	const g = {name: 'g', f: 1.0};
	const h = {name: 'h', f: 1.0};
	const i = {name: 'i', f: 1.0};
	const j = {name: 'j', f: 1.0}; 
	const k = {name: 'k', f: 1.0}; 
	const l = {name: 'l', f: 1.0}; 
	const m = {name: 'm', f: 1.0}; 

	m.mother=k;
	m.father=l;
	k.mother=g;
	k.father=h;
	l.mother=i;
	l.father=j;
	h.mother=c;
	h.father=d;
	i.mother=e;
	i.father=f;
	d.mother=a;
	d.father=b;
	e.mother=a;
	e.father=b;

	const persons = [a, b, c, d, e, f, g, h, i, j, k, l, m];

	init(persons);
	return coefficientOfRelationship(m, d);
}

console.log(testFigure8());
console.log(testFigure9());
console.log(testFigure10());
console.log(testFigure11());
console.log(testFigure12());