Mongo Map Reduce to Return an Array of Objects

I've been trying to use the MapReduce functionaltity in Mongo 2.6.11 to help in returning an array of objects as a value to a corresponding key.

For example, given the following input to a MapReduce job:

{ IncidentNumber : 123, StartLoc : 5, EndLoc : 10, },
{ IncidentNumber : 123, StartLoc : 10, EndLoc : 15, }, 
{ IncidentNumber : 123, SStartLoc : 10, EndLoc : 15, }, 
{ IncidentNumber : 321, StartLoc : 0, EndLoc : 5, }, 
{ IncidentNumber : 321, StartLoc : 10, EndLoc : 20, }

I would like to get output that looks like this:

{ IncidentNumber : 123, Locations : [{StartLoc : 5, EndLoc : 10},{StartLoc : 10, EndLoc : 15}, {StartLoc : 10, EndLoc : 15}],
{ IncidentNumber : 321, Locations : [{StartLoc : 0, EndLoc : 5},{StartLoc : 10, EndLoc : 20}]

My current map and reduce functions for this is as follows:

var mapFunction = function() {
    emit(this.IncidentNumber, {StartLoc : this.StartLoc, EndLoc: this.EndLoc} )
}

var reduceFunction = function(key, values) {
    var out = []
    return out.push(values);
}

This is giving me results that look like:

{ "_id" : 50144, "value" : 1 }
{ "_id" : 68971, "value" : { "startLoc" : 10, "endLoc" : 5} }
{ "_id" : 108294, "value" : 1 }
{ "_id" : 165130, "value" : 1 }
{ "_id" : 194016, "value" : 1 }
{ "_id" : 210018, "value" : 1 }
{ "_id" : 210195, "value" : 1 }
{ "_id" : 212069, "value" : 1 }

I know my reduce function is not correct and I'm not sure if this is an odd use case as I'm not really doing any actual 'reduction'. But I'm not sure exactly what the problem is. Any help would be much appreciated.

Thanks.

After some more searching I found a way of a getting this to work based on this post MongoDB Map/Reduce Array aggregation question. For anyone who is trying to solve the same problem The map/reduce functions I've used are as follows:

var mapFunction = function() {
  emit( { 
    incident: this.IncidentNumber, 
  } , { 
    data: [ { start : this.startLoc, end : this.endLoc} ]
  } );
}
var reduceFunction = function(key,values) {
  var out = [];
  values.forEach(function(d){
    Array.prototype.push.apply(out, d.data);
  });
  return { data: out };
}