ucar.nc2.iosp

Class IndexChunker

java.lang.Object

ucar.nc2.iosp.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());
   }
 }
 

Since:

Jan 2, 2008

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	IndexChunker.Chunk A chunk of data that is contiguous in both the source and destination.

Constructor Summary

Constructors

Constructor and Description
IndexChunker(int[] srcShape, Section wantSection) Constructor

Method Summary

Modifier and Type	Method and Description
long	getTotalNelems() Get total number of elements in wantSection
boolean	hasNext() If there are more chunks to process
IndexChunker.Chunk	next() Get the next chunk
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

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, ie must be subset of srcShape.

Throws:

InvalidRangeException - if wantSection is incorrect

Method Detail

getTotalNelems

public long getTotalNelems()

Get total number of elements in wantSection

Returns:

total number of elements in wantSection

hasNext

public boolean hasNext()

If there are more chunks to process

Returns:

true if there are more chunks to process

next

public IndexChunker.Chunk next()

Get the next chunk

Returns:

the next chunk

toString

public String toString()

Overrides:

toString in class Object