private async Task <List <Node> > GetLeafNodesAsync(List <IClusterableMatch> clusterableMatches, ConcurrentDictionary <int, float[]> matrix, int maxIndex, IDistanceMetric distanceMetric, ProgressData progressData)
{
var average = clusterableMatches.Average(match => match.Coords.Count());
progressData.Reset($"Calculating coordinates for {clusterableMatches.Count} matches (average {average:N0} shared matches per match)...", clusterableMatches.Count);
var leafNodes = await Task.Run(() =>
{
return(clusterableMatches
.Where(match => matrix.ContainsKey(match.Index))
.Select(match => new LeafNode(match.Index, matrix[match.Index], distanceMetric))
.ToList());
});
progressData.Reset($"Finding closest pairwise distances for {clusterableMatches.Count} matches (average {average:N0} shared matches per match)...", clusterableMatches.Count);
var buckets = leafNodes
.SelectMany(leafNode => distanceMetric.SignficantCoordinates(leafNode.Coords).Select(coord => new { Coord = coord, LeafNode = leafNode }))
.GroupBy(pair => pair.Coord, pair => pair.LeafNode)
.ToDictionary(g => g.Key, g => g.ToList());
var calculateNeighborsByDistanceTasks = leafNodes.Select(async leafNode =>
{
leafNode.NeighborsByDistance = await Task.Run(() => GetNeighborsByDistance(leafNode, buckets, distanceMetric));
progressData.Increment();
});
await Task.WhenAll(calculateNeighborsByDistanceTasks);
var result = leafNodes.Where(leafNode => leafNode.NeighborsByDistance.Count > 0).ToList <Node>();
progressData.Reset();
return(result);
}
private List <Neighbor> GetNeighborsByDistance(LeafNode leafNode, IDictionary <int, List <LeafNode> > buckets, IDistanceMetric distanceMetric)
{
var neighbors = distanceMetric.SignficantCoordinates(leafNode.Coords)
// Get every node with at least one shared match in common
.SelectMany(coord => buckets.TryGetValue(coord, out var bucket) ? bucket : Enumerable.Empty <LeafNode>())
// We only need one direction A -> B (not also B -> A) since we're ultimately going to look at the smallest distances.
.Where(neighborNode => neighborNode.Index > leafNode.Index)
// Make sure that each node is considered only once (might have been in more than one bucket if more than one shared match in common.
.Distinct()
.Select(neighborNode => new Neighbor(neighborNode, leafNode))
.OrderBy(neighbor => neighbor.DistanceSquared)
.ToList();
return(neighbors);
}