couchdb map reduce brightness

brightmapreduce.js

//brightness : http://couchdb.ovh:5984/database/_design/mesures/_view/brightness?group=true

//map :

function(doc, req) {

	var date = dateFromISO8601(doc.datetime);

  	emit(date.getDate(), doc.brightness);

}

function dateFromISO8601(isostr) {
	var parts = isostr.match(/\d+/g);
	return new Date(parts[0], parts[1] - 1, parts[2], parts[3], parts[4], parts[5]);
}

//reduce :

avg_function = function(keys, values, rereduce) {
    var avg, length;
    if (!rereduce) {
        length = values.length;
        return [sum(values) / length, length];
    } else {
        length = sum(values.map(function(v) {
            return v[1];
        }));
        avg = sum(values.map(function(v) {
            return v[0] * (v[1] / length);
        }));
        return [avg, length];
    }
};