example

curl -XPUT 'localhost:9200/example' -d '
{
 "mappings":{
  "nestedTravels":{
   "_source":{
    "enabled":"true"
   },
   "properties":{
    "TravelsByHour":{
     "type":"nested",
     "properties":{
      "state":{
       "type":"string"
      },
      "count":{
       "type":"integer"
      }
     }  
    },
    "CI":{
     "properties":{
      "CIStation":{
       "type":"string"
      },
      "CIName":{
       "type":"string"
      },
      "CIGeo":{
       "type":"geo_point"
      }
     }
    },
    "CO":{
     "properties":{
      "COStation":{
       "type":"string"
      },
      "COName":{
       "type":"string"
      },
      "COGeo":{
       "type":"geo_point"
      }
     }
    },
    "TravelDate":{
     "type":"date",
     "format":"yyyy-MM-dd"
    },
    "CIMode":{
     "type":"string"
    }
   }
  }
 }
}
'


curl -XPUT 'localhost:9200/example/nestedTravels/123' -d '
{
 "TravelsByHour":[{
  "state":"05",
  "count":54
 },{
  "state":"06",
  "count":1
 },{
  "state":"07",
  "count":1
 },{
  "state":"16",
  "count":6
 },{
  "state":"20",
  "count":1
 },{
  "state":"23",
  "count":8
 }],
 "CI":{
  "CIStation":"10",
  "CIName":"Station 1",
  "CIGeo":{
   "lat":80.50,
   "lon":80.50
  }
 },
 "CO":{
  "COStation":"39",
  "COName":"Station 2",
  "COGeo":{
   "lat":80.50,
   "lon":80.51
  }
 },
 "TravelDate":"2013-06-27",
 "CIMode":"Train"
}
'

curl -XPUT 'localhost:9200/example/nestedTravels/456' -d '
{
 "TravelsByHour":[{
  "state":"01",
  "count":10
 },{
  "state":"07",
  "count":12
 },{
  "state":"16",
  "count":5
 },{
  "state":"29",
  "count":1
 },{
  "state":"23",
  "count":9
 }],
 "CI":{
  "CIStation":"10",
  "CIName":"Station 1",
  "CIGeo":{
   "lat":80.50,
   "lon":80.50
  }
 },
 "CO":{
  "COStation":"39",
  "COName":"Station 2",
  "COGeo":{
   "lat":80.50,
   "lon":80.51
  }
 },
 "TravelDate":"2013-06-28",
 "CIMode":"Train"
}
'

# terms stats facets, the result is close from what I want
curl -XPOST 'localhost:9200/example/_search?pretty=true' -d '
{
 "facets": {
  "myFacet": {
   "terms_stats": {
    "key_field": "TravelsByHour.state",
    "value_field": "TravelsByHour.count"
   },
   "nested": "TravelsByHour"
  }
 }
}
'

# There is an error here: nested: ClassCastException[org.elasticsearch.index.fielddata.plain.PagedBytesIndexFieldData cannot be cast to org.elasticsearch.index.fielddata.IndexNumericFieldData]
curl -XPOST 'localhost:9200/example/_search?pretty=true' -d '
{
 "facets": {
  "myFacet": {
   "histogram": {
    "key_field": "TravelsByHour.state",
    "value_field": "TravelsByHour.count",
    "interval": 100
   }
  }
 }
}
'