io.improbable.keanu.tensor.jvm

Class SlicerIndexMapper

java.lang.Object

io.improbable.keanu.tensor.jvm.SlicerIndexMapper

All Implemented Interfaces:

IndexMapper

public final class SlicerIndexMapper
extends java.lang.Object
implements IndexMapper

This class provides shape calculation and index mapping for the slice operation. Given a description of slices (Slicer) and a source shape and stride, the shape of the slice operation can be calculated.

Ths class stores the result shape without dropping the dimensions that are ultimately dropped in order to more efficiently calculate source to result index mappings.

Dimensions are dropped for example given 1:2,3 then the 2nd dimension length will be 1 and ALSO dropped but the first dimension will be kept despite also being length one. This is done this way to mimic numpy behaviour.

Constructor Summary

Constructors

Constructor and Description
SlicerIndexMapper(Slicer slicer, long[] sourceShape, long[] sourceStride)

Method Summary

Modifier and Type	Method and Description
long[]	getResultShape()
long[]	getResultStride()
long	getSourceIndexFromResultIndex(long resultIndex)

Methods inherited from class java.lang.Object

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

Constructor Detail

SlicerIndexMapper

public SlicerIndexMapper(Slicer slicer,
                         long[] sourceShape,
                         long[] sourceStride)

Method Detail

getResultShape

public long[] getResultShape()

Specified by:

getResultShape in interface IndexMapper

Returns:

The resultShapeWithoutRankLoss with the dropped dimensions dropped.

getResultStride

public long[] getResultStride()

Specified by:

getResultStride in interface IndexMapper

Returns:

The resultStrideWithoutRankLoss with the dropped dimensions dropped.

getSourceIndexFromResultIndex

public long getSourceIndexFromResultIndex(long resultIndex)

Specified by:

getSourceIndexFromResultIndex in interface IndexMapper

Parameters:

resultIndex - the index in the result buffer

Returns:

the index in the source buffer that maps to the result buffer.