Ranked lists in lodash

gistfile1.js

// Use _.mixin to extend lodash
_.mixin({
    'rankedBy': function(c, rank_cb, reversed) {
        var ranks = [], pos = 0, _ = this;
        
        var grouped = _.groupBy(c, rank_cb);
        ranks = _.sortBy(grouped, function(v) {
            return rank_cb(v[0]);
        });
        if (reversed) {
            ranks = (ranks.reverse());
        }
        return ranks;
    }
});
 
// Test
var myarr = [
    {
        "name": "Anna",
        "score": 123
    },
    {
        "name": "Borat",
        "score": 456
    },
    {
        "name": "Cecil",
        "score": 321
    },
    {
        "name": "George",
        "score": 456
    }
];
var score_cb = function(p) { return p.score; };
var print = function(ranked) {
    _.each(ranked, function(rank, idx) {
        var names = _.map(rank, function(v){ return v.name; });
        console.log((1+idx)+'.' , '(' + rank[0].score + ')' , names.join(', '));
    });
};

console.log('Testrun');
print(_.rankedBy(myarr, score_cb));

console.log('Testrun wrapped');
print(_(myarr).rankedBy(score_cb));

console.log('Reversed');
print(_.rankedBy(myarr, score_cb, true));

Test available at http://jsfiddle.net/spoike/hUJeF/