scope3

scope3.java

DBCollection coll = db.getCollection("collection"); 

String map = "function() {" +
	"if(this.arrayOfStuff) {" +
		"this.arrayOfStuff.forEach(function(stuff) {" +
			"if(stuff.date > from && stuff.date < to) {" +
				"var date = Date.UTC(stuff.date.getFullYear(), stuff.date.getMonth(), stuff.date.getDate(), stuff.date.getHours());" +
				"emit({day: date}, {count:1});" +
			"}" +
		"});" +  
	"}" +
"};";

String reduce = "function(key , values) {" +
	"var total = 0;" +
	"values.forEach(function(v) {" +
		"total += v.count;" +
	"});" +
	"return {count : total};" +
"};";

DBObject query = new BasicDBObject();
query.put("meh", meh);

MapReduceCommand cmd = new MapReduceCommand(coll, map, reduce, null, MapReduceCommand.OutputType.INLINE, query);
Map scope = new HashMap();
scope.put("from", from);
scope.put("to", to);
cmd.setScope(scope);
MapReduceOutput out = coll.mapReduce(cmd);