public bool ContainsGeoHash(GeoHash hash)
{
var hashStr = hash.GetGeoHashString();
return(Compare(_startValue, hashStr, StringComparison.Ordinal) <= 0 &&
Compare(_endValue, hashStr, StringComparison.Ordinal) > 0);
}
public static GeoHashQuery QueryForGeoHash(GeoHash geohash, int bits)
{
var hash = geohash.GetGeoHashString();
var precision = (int)Math.Ceiling((double)bits / Base32Utils.BitsPerBase32Char);
if (hash.Length < precision)
{
return(new GeoHashQuery(hash, hash + "~"));
}
hash = hash.Substring(0, precision);
var hashBase = hash.Substring(0, hash.Length - 1);
var lastValue = Base32Utils.Base32CharToValue(hash[hash.Length - 1]);
var significantBits = bits - hashBase.Length * Base32Utils.BitsPerBase32Char;
var unusedBits = Base32Utils.BitsPerBase32Char - significantBits;
// delete unused bits
var startValue = (lastValue >> unusedBits) << unusedBits;
var endValue = startValue + (1 << unusedBits);
var startHash = hashBase + Base32Utils.ValueToBase32Char(startValue);
var endHash = endValue > 31 ? hashBase + "~" : hashBase + Base32Utils.ValueToBase32Char(endValue);
return(new GeoHashQuery(startHash, endHash));
}
public static HashSet <GeoHashQuery> QueriesAtLocation(GeoPoint location, double radius)
{
var queryBits = Math.Max(1, Utils.BitsForBoundingBox(location, radius));
var geoHashPrecision = (int)Math.Ceiling((float)queryBits / Base32Utils.BitsPerBase32Char);
var latitude = location.Latitude;
var longitude = location.Longitude;
var latitudeDegrees = radius / Constants.MetersPerDegreeLatitude;
var latitudeNorth = Math.Min(90, latitude + latitudeDegrees);
var latitudeSouth = Math.Max(-90, latitude - latitudeDegrees);
var longitudeDeltaNorth = GeoUtils.DistanceToLongitudeDegrees(radius, latitudeNorth);
var longitudeDeltaSouth = GeoUtils.DistanceToLongitudeDegrees(radius, latitudeSouth);
var longitudeDelta = Math.Max(longitudeDeltaNorth, longitudeDeltaSouth);
var queries = new HashSet <GeoHashQuery>();
var geoHash = new GeoHash(latitude, longitude, geoHashPrecision);
var geoHashW = new GeoHash(latitude, GeoUtils.WrapLongitude(longitude - longitudeDelta), geoHashPrecision);
var geoHashE = new GeoHash(latitude, GeoUtils.WrapLongitude(longitude + longitudeDelta), geoHashPrecision);
var geoHashN = new GeoHash(latitudeNorth, longitude, geoHashPrecision);
var geoHashNw = new GeoHash(latitudeNorth, GeoUtils.WrapLongitude(longitude - longitudeDelta), geoHashPrecision);
var geoHashNE = new GeoHash(latitudeNorth, GeoUtils.WrapLongitude(longitude + longitudeDelta), geoHashPrecision);
var geoHashS = new GeoHash(latitudeSouth, longitude, geoHashPrecision);
var geoHashSW = new GeoHash(latitudeSouth, GeoUtils.WrapLongitude(longitude - longitudeDelta), geoHashPrecision);
var geoHashSE = new GeoHash(latitudeSouth, GeoUtils.WrapLongitude(longitude + longitudeDelta), geoHashPrecision);
queries.Add(QueryForGeoHash(geoHash, queryBits));
queries.Add(QueryForGeoHash(geoHashE, queryBits));
queries.Add(QueryForGeoHash(geoHashW, queryBits));
queries.Add(QueryForGeoHash(geoHashN, queryBits));
queries.Add(QueryForGeoHash(geoHashNE, queryBits));
queries.Add(QueryForGeoHash(geoHashNw, queryBits));
queries.Add(QueryForGeoHash(geoHashS, queryBits));
queries.Add(QueryForGeoHash(geoHashSE, queryBits));
queries.Add(QueryForGeoHash(geoHashSW, queryBits));
// Join queries
bool didJoin;
do
{
GeoHashQuery query1 = null;
GeoHashQuery query2 = null;
foreach (var query in queries)
{
foreach (var other in queries.Where(other => query != other && query.CanJoinWith(other)))
{
query1 = query;
query2 = other;
break;
}
}
if (query1 != null && query2 != null)
{
queries.Remove(query1);
queries.Remove(query2);
queries.Add(query1.JoinWith(query2));
didJoin = true;
}
else
{
didJoin = false;
}
} while (didJoin);
return(queries);
}
