/// <summary>
/// Reads a cluster centre from a binary file.
/// </summary>
/// <param name="fileIn">The input file.</param>
/// <param name="coordCount">The number of vertex coordinates to read.</param>
/// <returns>Returns the read centre.</returns>
public static Centre ReadBinary(System.IO.BinaryReader fileIn, ushort coordCount)
{
// check that we are loading the right types
System.Diagnostics.Debug.Assert(FileAddressSize == sizeof(long));
System.Diagnostics.Debug.Assert(ChildrenCountSize == sizeof(int));
// create the cluster centre
Centre c = new Centre();
// read the vertex coordinates
c.vertex = Vertex.ReadBinary(fileIn, coordCount);
// read children information
c.childrenFileStart = fileIn.ReadInt64();
c.childrenCount = fileIn.ReadInt32();
return(c);
}
/// <summary>
/// Loads all members of the given cluster.
/// </summary>
/// <param name="level">The level from where to load the members (one level lower than the cluster centre).</param>
/// <param name="startIndex">Index of the first cluster member.</param>
/// <param name="count">Number of the cluster members.</param>
/// <returns>Returns an array of cluster vertices.</returns>
public Centre[] ExpandCluster(int level, long startIndex, int count)
{
// open input file
string fileName = GetNumberedFileName(level);
FileStream streamIn = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
BinaryReader fileIn = new BinaryReader(streamIn);
// read the number of coordinates each vertex has
ushort coordCount = fileIn.ReadUInt16();
// seek to the appropriate cluster
streamIn.Seek(startIndex, SeekOrigin.Begin);
// prepare memory
Centre[] clusterMembers = new Centre[count];
// load the cluster members
if (level > 0)
{
for (int i = 0; i < count; i++)
{
clusterMembers[i] = Centre.ReadBinary(fileIn, coordCount);
}
}
else
{
for (int i = 0; i < count; i++)
{
clusterMembers[i] = Centre.ReadBinaryJustCoords(fileIn, coordCount);
}
}
// close input file
fileIn.Close();
streamIn.Close();
return(clusterMembers);
}
/// <summary>
/// Adds more centres for clustering.
/// </summary>
/// <param name="centres">The centres to add.</param>
/// <param name="level">The level where to add.</param>
private void PushVertices(Centre[] centres, int level)
{
if (finished)
{
throw new ApplicationException("The input stream has already been finished.");
}
// get the appropriate clustering level
ClusteringLevel cl = clusteringLevels[level];
// is there enough free space?
if (centres.Length <= cl.FreeSpace)
{
// yes, add all the vertices right away
cl.PushVertices(centres);
}
else
{
// no, add the vertices by pieces
int remainToPush = centres.Length;
int alreadyPushed = 0;
int free = cl.FreeSpace;
// prepare the first piece
Centre[] pieceToPush = new Centre[free];
Array.Copy(centres, alreadyPushed, pieceToPush, 0, free);
// push the first piece
cl.PushVertices(pieceToPush);
remainToPush -= free;
alreadyPushed += free;
// process the full block
ProcessLevel(level);
pieceToPush = new Centre[blockSize];
// push further pieces
while (remainToPush > blockSize)
{
// prepare a single piece
Array.Copy(centres, alreadyPushed, pieceToPush, 0, blockSize);
// push the piece
cl.PushVertices(pieceToPush);
remainToPush -= blockSize;
alreadyPushed += blockSize;
// process the full block
ProcessLevel(level);
}
// copy the last remaining piece
pieceToPush = new Centre[remainToPush];
Array.Copy(centres, alreadyPushed, pieceToPush, 0, remainToPush);
// push the last remaining piece
cl.PushVertices(pieceToPush);
}
// check whether there is still some space for further vertices
if (cl.FreeSpace == 0)
{
// no, the level is exactly full, let's process it
ProcessLevel(level);
}
}
