// Example 3 : Get the Eldest and Youngest Person in each gender

var mongojs = require('mongojs');
var db = mongojs('mapReduceDB', ['sourceData', 'example2_results']);


var mapper = function () {
	var x = {age : this.age, name : this.name};
	emit(this.gender, {min : x , max : x});
};


var reducer = function(key, values){
 	var res = values[0];
 	for (var i = 1; i < values.length; i++) {
 		if(values[i].min.age < res.min.age)
 			res.min = {name : values[i].min.name, age : values[i].min.age};
        if (values[i].max.age > res.max.age)
           res.max = {name : values[i].max.name, age : values[i].max.age};
 	};
 	return res;
};

db.sourceData.mapReduce(
	mapper,
	reducer,
	{
		out : "example2_results"
	}
 );

 db.example2_results.find(function (err, docs) {
 	if(err) console.log(err);
 	console.log(JSON.stringify(docs));
 });