Package ucar.nc2.iosp

Class IndexChunker

  • public class IndexChunker
extends Object
    Iterator to read/write subsets of a multidimensional array, finding the contiguous chunks. The iteration is monotonic in both src and dest positions.

    Example for Integers: 

     int[] read(IndexChunker index, int[] src) {
   int[] dest = new int[index.getTotalNelems()];
   while (index.hasNext()) {
     Indexer2.Chunk chunk = index.next();
     System.arraycopy(src, chunk.getSrcElem(), dest, chunk.getDestElem(), chunk.getNelems());
   }
   return dest;
 }
 
 int[] read(IndexChunker index, RandomAccessFile raf, long start_pos) {
   int[] dest = new int[index.getTotalNelems()];
   while (index.hasNext()) {
     Indexer2.Chunk chunk = index.next();
     raf.seek(start_pos + chunk.getSrcElem() * 4);
     raf.readInt(dest, chunk.getDestElem(), chunk.getNelems());
   }
   return dest;
 }
 
 // note src and dest misnamed
 void write(IndexChunker index, int[] src, RandomAccessFile raf, long start_pos) {
   while (index.hasNext()) {
     Indexer2.Chunk chunk = index.next();
     raf.seek(start_pos + chunk.getSrcElem() * 4);
     raf.writeInt(src, chunk.getDestElem(), chunk.getNelems());
   }
 }

    • Constructor Detail

      • IndexChunker

        public IndexChunker​(int[] srcShape,
                    @Nullable
                    Section wantSection)
             throws InvalidRangeException
        Constructor
        Parameters:
        srcShape - the shape of the source, eg Variable.getShape()
        wantSection - the wanted section in srcShape, must be subset of srcShape.
        Throws:
        InvalidRangeException - if wantSection is incorrect

    • Method Detail

      • getTotalNelems

        public long getTotalNelems()
        Get total number of elements in wantSection

      • hasNext

        public boolean hasNext()
        If there are more chunks to process