public async Task<SearchResult[]> Search(Position position, double radius)
{
var tasks = new List<Task<KeyValuePosition[]>>();
foreach (var key in position.GetQuadKeysInRadius(radius))
{
var quadKeyGrain = GrainFactory.GetGrain<IQuadKeyGrain>(key);
tasks.Add(quadKeyGrain.GetItems());
}
await Task.WhenAll(tasks);
var results = new List<SearchResult>();
foreach (var item in tasks)
{
results.AddRange(item.Result.Select(x =>
{
return new SearchResult
{
ETag = x.ETag,
Key = x.Key,
Position = x.Position,
Value = x.Value,
Distance = x.Position.DistanceTo(position)
};
}));
}
return results.Where(x => x.Distance <= radius).ToArray();
}
public static IEnumerable<Change> GetDelta(this Position from, Position to)
{
if (from != null && from.Latitude == 0 && from.Longitude == 0) from = null;
if (to != null && to.Latitude == 0 && to.Longitude == 0) to = null;
return GetDelta(from.ToQuadKey(), to.ToQuadKey());
}
public void TestDistanceBetweenPoints()
{
var position1 = new Position { Latitude = 50, Longitude = 1 };
var position2 = new Position { Latitude = 51, Longitude = 2 };
var distance = position1.DistanceTo(position2);
// should be about 131 km
Assert.AreEqual(131, Math.Floor(distance / 1000));
}
public static double DistanceTo(this Position position1, Position position2)
{
var φ1 = DegreesToRadians(position1.Latitude);
var φ2 = DegreesToRadians(position2.Latitude);
var Δφ = DegreesToRadians(position2.Latitude - position1.Latitude);
var Δλ = DegreesToRadians(position2.Longitude - position1.Longitude);
var a = Math.Sin(Δφ / 2) * Math.Sin(Δφ / 2) + Math.Cos(φ1) * Math.Cos(φ2) * Math.Sin(Δλ / 2) * Math.Sin(Δλ / 2);
var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
return EarthRadius * c;
}
public void TestGetQuadKeysInRadius()
{
var keys = new Position { Latitude = 50, Longitude = 1 }.GetQuadKeysInRadius(1000).ToArray();
Assert.AreEqual(9, keys.Length);
var keys2 = new Position { Latitude = 50, Longitude = 1 }.GetQuadKeysInRadius(10000).ToArray();
Assert.AreEqual(9, keys2.Length);
Assert.AreNotEqual(keys[0], keys2[0]);
Assert.IsTrue(keys[4].StartsWith(keys2[4]));
}
public void TestGetQuadKey()
{
var key = new Position { Latitude = 50, Longitude = 1 }.ToQuadKey();
Assert.IsNotNull(key);
Assert.AreEqual(23, key.Length);
}
