Package uk.ac.starlink.array
Class PixelMapArrayImpl
- java.lang.Object
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- uk.ac.starlink.array.WrapperArrayImpl
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- uk.ac.starlink.array.PixelMapArrayImpl
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- 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. AnOffsetMapper
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
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Constructor Summary
Constructors Constructor 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.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method 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
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Constructor Detail
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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 pixelsoshape
- the shape and pixel sequence of the NDArray to be constructedmapper
- 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:
java.lang.UnsupportedOperationException
- if nda does not have random access
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Method Detail
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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 interfaceArrayImpl
- Overrides:
getShape
in classWrapperArrayImpl
- Returns:
- the ordered shape
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getAccess
public AccessImpl getAccess() throws java.io.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 interfaceArrayImpl
- Overrides:
getAccess
in classWrapperArrayImpl
- Returns:
- an accessor for the pixel data
- Throws:
java.io.IOException
- if there is an IO error
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