uk.ac.starlink.array

Class PixelMapArrayImpl

java.lang.Object

uk.ac.starlink.array.WrapperArrayImpl

uk.ac.starlink.array.PixelMapArrayImpl

All Implemented Interfaces:

ArrayImpl

public class PixelMapArrayImpl
extends WrapperArrayImpl

Wraps an NDArray to produce a virtual ArrayImpl in which each pixel is the same as a pixel of the base array, but in a different order. An OffsetMapper object is used to define the mapping between pixels in the base array and pixels in this array.

Note that no assumptions about contiguity of pixels can be made while doing bulk data access on a PixelMapNDArray; where applicable a WindowArrayImpl is likely to be more efficient.

Author:

Mark Taylor (Starlink)

See Also:

OffsetMapper, WindowArrayImpl

Constructor Summary

Constructors

Constructor and Description
PixelMapArrayImpl(NDArray nda, OrderedNDShape oshape, OffsetMapper mapper) Constructs a new ArrayImpl from a base NDArray and an OffsetMapper object which transforms the offset of a pixel in the base array to the offset of the same pixel in this PixelMapArrayImpl.

Method Summary

Modifier and Type	Method and Description
AccessImpl	getAccess() Returns an object which can access the pixels of this ArrayImpl.
OrderedNDShape	getShape() Returns an object representing the shape (origin and dimensions) and pixel sequence of this object.

Methods inherited from class uk.ac.starlink.array.WrapperArrayImpl

canMap, close, getBadValue, getMapped, getType, getWrapped, isRandom, isReadable, isWritable, multipleAccess, open, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

PixelMapArrayImpl

public PixelMapArrayImpl(NDArray nda,
                         OrderedNDShape oshape,
                         OffsetMapper mapper)

Constructs a new ArrayImpl from a base NDArray and an OffsetMapper object which transforms the offset of a pixel in the base array to the offset of the same pixel in this PixelMapArrayImpl. Since for a non-degenerate case a monotonic pixel offset ordering in a PixelMapNDArray is likely to correspond to a non-monotonic offset ordering in its base array, it is only permitted to construct a PixelMapNDArray from a base array which offers random access.

Parameters:

nda - the base NDArray which supplies the pixels

oshape - the shape and pixel sequence of the NDArray to be constructed

mapper - an OffsetMapper object which turns the offset of a pixel in this NDArray into the offset of the corresponding pixel in the base NDArray

Throws:

UnsupportedOperationException - if nda does not have random access

Method Detail

getShape

public OrderedNDShape getShape()

Description copied from interface: ArrayImpl

Returns an object representing the shape (origin and dimensions) and pixel sequence of this object. The return value must not change over the lifetime of the object.

Specified by:

getShape in interface ArrayImpl

Overrides:

getShape in class WrapperArrayImpl

Returns:

the ordered shape

getAccess

public AccessImpl getAccess()
                     throws IOException

Description copied from interface: ArrayImpl

Returns an object which can access the pixels of this ArrayImpl. Each call to this method returns a new and independent AccessImpl, with an offset initialised to 0 (the start of the array data).

This method will only be called after the sole call to open and before the sole call to close.

This method will only be called more than once if the multipleAccess method returns true.

It is the responsibility of the caller to close the returned AccessImpl when it is no longer required; this enables resources it may hold to be released.

Specified by:

getAccess in interface ArrayImpl

Overrides:

getAccess in class WrapperArrayImpl

Returns:

an accessor for the pixel data

Throws:

IOException - if there is an IO error