org.apache.sysml.runtime.compress

Class BitmapEncoder

java.lang.Object

org.apache.sysml.runtime.compress.BitmapEncoder

public class BitmapEncoder
extends Object

Static functions for encoding bitmaps in various ways.

Field Summary

Fields

Modifier and Type	Field and Description
static int	BITMAP_BLOCK_SZ Size of the blocks used in a blocked bitmap representation.

Constructor Summary

Constructors

Constructor and Description
BitmapEncoder()

Method Summary

Modifier and Type	Method and Description
static UncompressedBitmap	extractBitmap(int[] colIndices, MatrixBlock rawblock) Generate uncompressed bitmaps for a set of columns in an uncompressed matrix block.
static UncompressedBitmap	extractBitmapFromSample(int[] colIndices, MatrixBlock rawblock, int[] sampleIndexes)
static char[]	genOffsetBitmap(int[] offsets, int len) Encodes the bitmap in blocks of offsets.
static char[]	genRLEBitmap(int[] offsets, int len) Encodes the bitmap as a series of run lengths and offsets.
static int	getAlignedBlocksize(int blklen)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BITMAP_BLOCK_SZ

public static final int BITMAP_BLOCK_SZ

Size of the blocks used in a blocked bitmap representation.

See Also:

Constant Field Values

Constructor Detail

BitmapEncoder

public BitmapEncoder()

Method Detail

getAlignedBlocksize

public static int getAlignedBlocksize(int blklen)

extractBitmap

public static UncompressedBitmap extractBitmap(int[] colIndices,
                                               MatrixBlock rawblock)

Generate uncompressed bitmaps for a set of columns in an uncompressed matrix block.

Parameters:

colIndices - indexes (within the block) of the columns to extract

rawblock - an uncompressed matrix block; can be dense or sparse

Returns:

uncompressed bitmap representation of the columns

extractBitmapFromSample

public static UncompressedBitmap extractBitmapFromSample(int[] colIndices,
                                                         MatrixBlock rawblock,
                                                         int[] sampleIndexes)

genRLEBitmap

public static char[] genRLEBitmap(int[] offsets,
                                  int len)

Encodes the bitmap as a series of run lengths and offsets.

Parameters:

offsets - uncompressed offset list

len - logical length of the given offset list

Returns:

compressed version of said bitmap

genOffsetBitmap

public static char[] genOffsetBitmap(int[] offsets,
                                     int len)

Encodes the bitmap in blocks of offsets. Within each block, the bits are stored as absolute offsets from the start of the block.

Parameters:

offsets - uncompressed offset list

len - logical length of the given offset list

Returns:

compressed version of said bitmap