/// <summary>
/// Merge all the members of the partitions labeled by any of the labels in sourceLabels
/// into the partition indicated by targetLabel.
/// </summary>
/// <param name="targetLabel">Move members into this labeled partition.</param>
/// <param name="sourceLabels">Move members out of these labeled partitions.</param>
/// <returns>True if at least one point was added to the targetLabel's partition.
/// False if the target partition did not increase in size.</returns>
public bool Merge(TLabel targetLabel, IEnumerable <TLabel> sourceLabels)
{
var targetPartition = EnsurePartition(targetLabel);
var startingSize = targetPartition.Count;
foreach (var sourceLabel in sourceLabels.Where(sLabel => !sLabel.Equals(targetLabel)))
{
ISet <TPoint> singleSourcePoints;
if (!LabelToPoints.TryGetValue(sourceLabel, out singleSourcePoints))
{
continue;
}
// Add to LabelToPoints under new targetLabel
targetPartition.UnionWith(singleSourcePoints);
// Remove from LabelToPoints under old sourceLabel.
LabelToPoints.Remove(sourceLabel);
foreach (var p in singleSourcePoints)
{
PointToLabel[p] = targetLabel;
}
}
return(startingSize < targetPartition.Count);
}
private ISet <TPoint> EnsurePartition(TLabel classLabel)
{
ISet <TPoint> partition;
if (LabelToPoints.TryGetValue(classLabel, out partition))
{
return(partition);
}
partition = new HashSet <TPoint>();
LabelToPoints[classLabel] = partition;
return(partition);
}
/// <summary>
/// Remove a point from its class.
/// </summary>
/// <param name="p">Point to remove.</param>
/// <returns>True if the point was removed, false if it was not previously a member of any class.</returns>
public bool Remove(TPoint p)
{
TLabel label;
if (!PointToLabel.TryGetValue(p, out label))
{
return(false);
}
PointToLabel.Remove(p);
var oldPoints = LabelToPoints[label];
var didRemove = oldPoints.Remove(p);
if (oldPoints.Count == 0)
{
LabelToPoints.Remove(label);
}
return(didRemove);
}
/// <summary>
/// Counts the number of partitions whose size equals or exceeds the given number.
/// </summary>
/// <param name="minSize">Minimum size of partitions to be counted.</param>
/// <returns>The number of partitions that are large enough.</returns>
public int NumLargePartitions(int minSize)
{
return(LabelToPoints.Count(p => p.Value.Count >= minSize));
}
