func worldCapitals(context appengine.Context) []index.Point {
file, err := os.OpenFile("static/capitals.csv", os.O_RDONLY, 0)
if err != nil {
context.Errorf("%v", err)
return make([]index.Point, 0)
}
defer file.Close()
reader := csv.NewReader(file)
reader.Comma = '\t'
records, _ := reader.ReadAll()
capitals := make([]index.Point, 0)
for _, record := range records {
id := record[0]
lat, _ := strconv.ParseFloat(record[3], 64)
lon, _ := strconv.ParseFloat(record[4], 64)
capital := index.NewGeoPoint(id, lat, lon)
capitals = append(capitals, capital)
}
return capitals
}
func knearest(w http.ResponseWriter, r *http.Request) {
r.ParseForm()
lat, _ := strconv.ParseFloat(r.Form["lat"][0], 64)
lon, _ := strconv.ParseFloat(r.Form["lon"][0], 64)
k, _ := strconv.ParseInt(r.Form["k"][0], 10, 32)
c := appengine.NewContext(r)
nearest := getIndex(c).KNearest(index.NewGeoPoint("query", lat, lon), int(k), index.Km(5), func(_ index.Point) bool { return true })
data, _ := json.Marshal(nearest)
fmt.Fprintln(w, string(data))
}
func points(w http.ResponseWriter, r *http.Request) {
r.ParseForm()
topLeftLat, _ := strconv.ParseFloat(r.Form["topLeftLat"][0], 64)
topLeftLon, _ := strconv.ParseFloat(r.Form["topLeftLon"][0], 64)
bottomRightLat, _ := strconv.ParseFloat(r.Form["bottomRightLat"][0], 64)
bottomRightLon, _ := strconv.ParseFloat(r.Form["bottomRightLon"][0], 64)
c := appengine.NewContext(r)
visiblePoints := getIndex(c).Range(index.NewGeoPoint("topLeft", topLeftLat, topLeftLon), index.NewGeoPoint("bottomRight", bottomRightLat, bottomRightLon))
data, _ := json.Marshal(visiblePoints)
fmt.Fprintln(w, string(data))
}
func getIndex(context appengine.Context) *index.ClusteringIndex {
if geoindex == nil {
geoindex = index.NewClusteringIndex()
capitals := worldCapitals(context)
id := 1
for _, capital := range capitals {
for i := 0; i < 300; i++ {
id++
geoindex.Add(index.NewGeoPoint(
fmt.Sprintf("%d", id),
capital.Lat()+rand.Float64()/6.0*sign(),
capital.Lon()+rand.Float64()/6.0*sign(),
))
}
}
}
return geoindex
}