A function to calculate the nearest match based on a shared set of ratings.

nearest.js

function manhattan(userRating, matchRating){
	/* 
	Calculates the manhattan distance between two ratings sets.
	ratings are objects like this:
	  {speed:1, fitness:3, likeability:6}
	We assume both sets have the same ratings categories, just different scores.
	*/
	var distance = 0;
	for (rating in userRating){
		distance = distance + Math.abs(userRating[rating] - matchRating[rating])
	}
	return distance;
}


function nearest(user, matches){
	/*
	Finds the nearest match according to a user's ratings.

	Let's assume user is an anonymous object with ratings like
	{goatee: 2, movieFacts: 7 ... }

	And that matches is an array of named ratings like:
	[	{ name: John,
		  ratings: {goatee: 10, movieFacts: 0 ... } },
		{ name: Layne,
		  ratings: {goatee:0, movieFacts:9 ... } },
		... 
		]
	*/

	var distances = [];
	for(i in matches){
		distance = manhattan(user, matches[i].ratings)
		distances.push( [matches[i].name, distance] )
	}
    
	return distances.sort(function(a,b){ return a[1] - b[1]; })[0] 

}

/*------------------------------------------------------*/
/*Example*/

var jon = {javascript:4, python:9, php:0, r:6, css:6, html:6, design: 0},

    guys = [
            {name: 'John',
            ratings: {javascript:8, python:4, php:0, r:0, css:10, html:10, design: 8} },
            {name: 'Troy',
            ratings: {javascript:7, python:5, php:0, r:0, css:10, html:10, design: 10} },
            {name: 'Layne',
            ratings: {javascript:10, python:4, php:6, r:0, css:7, html:10, design: 8} },
            {name: 'Daniel',
            ratings: {javascript:5, python:10, php:5, r:6, css:2, html:6, design: 0} },
        ];

nearest(jon, guys);