mapreduce.js

db.open(function(err, db) {
    db.collection('rounds', function(err, collection) {
        var name_letter = 'v';
        var map = function() {
            if (this.score1 > this.score2) {
                emit(this.player1, this.score1);
            } else {
                if (this.score2 > this.score1) emit(this.player2, this.score2)
            }
        };

        var reduce = function (k, vals) {var sum = 0;for(var i in vals) sum += vals[i];return (sum / vals.length); };

        collection.mapReduce(map, reduce, function(err, result) {
            if (err) {
                sys.puts('Err: ' + JSON.stringify(err));
            } else {
                result.findOne({'_id':'kze'}, function(err, scores) {
                    if (err) {
                       sys.puts('Err in results');
                    }
                    sys.puts('Kaze scores: ' + JSON.stringify(scores));
                });
                sys.puts('Mapreduce done');
            }



        });
    });

});