StokesCoordinate.h

virtual String format(String& units, Coordinate::formatType format, Double worldValue, uInt worldAxis, Bool isAbsolute=True, Bool showAsAbsolute=True, Int precision = -1)

virtual Bool near(const Coordinate& other, Double tol=1e-6) const

virtual Bool near(const Coordinate& other, const Vector<Int>& excludeAxes, Double tol=1e-6) const

virtual Bool save(RecordInterface &container, const String &fieldName) const

static StokesCoordinate* restore(const RecordInterface &container, const String &fieldName)

virtual Coordinate *clone() const

virtual Bool doNearPixel (const Coordinate& other, const Vector<Bool>& thisAxes, const Vector<Bool>& otherAxes, Double tol=1.0e-6) const

Private Members

Bool toWorld(Double& world, const Double pixel) const

Bool toPixel(Double& pixel, const Double world) const

StokesCoordinate()

Description

Review Status

Reviewed By:

Peter Barnes

Date Reviewed:

1999/12/24

Programs:

Tests:

tStokesCoordinate

Prerequisite

Synopsis

Although not really a "coordinate", an axis where pixel numbers are used for different Stokes values is in wide use. The StokesCoordinate is a poor fit to the Coordinate polymorphic model. You will probably find that if you try to use the Coordinate classes polymorphically, that StokesCoordinate will cause you to break the polymorphism. I.e. you may have to deal with a specific StokesCoordinate)

The StokesCoordinate just maintains a list (given in the constructor) of possibly non-monotonic Stokes values. The values of the list are the world values (they are values from the Stokes::StokesTypes enum). Thus world = list[pixel] where pixel is the pixel coordinate (0,1, ...)

This means that concepts such as reference pixel, reference value, increment etc are meaningless for StokesCoordinate. You can recover these these attributes, but the functions to set these attributes have no effect.

Note also that for the StokesCoordinate relative world coordinates are defined to be the as absolute, since there is no meaning for a relative Stokes world value (e.g. what is XX -RL ?? Relative pixel coordinates are defined.

All pixel coordinates are zero relative.

Example

In this example we create a StokesCoordinate housing IQUV

    Vector<Int> iquv(4);
    iquv(0) = Stokes::I; iquv(1) = Stokes::Q;
    iquv(2) = Stokes::U; iquv(3) = Stokes::V;
    StokesCoordinate stokes(iquv);

Motivation

It is conventional to make a pseudo-axis of Stokes parameters. Another approach is to make an image type called Stokes.

To Do

This could probably be generalized into an "enumeration axis" class.

Member Description

explicit StokesCoordinate(const Vector<Int> &whichStokes)

The length of whichStokes is the length of the axis, and the values define which stokes are in which axis value. Often the vector will be of length 4 and will contain Stokes::I, Q, U and V, however any valid value from the stokes enum may be used. The values may not repeat however, e.g. only one axis position may contain "I".

StokesCoordinate(const StokesCoordinate &other)

Copy constructor (copy semantics)

StokesCoordinate &operator=(const StokesCoordinate &other)

Assignment (copy semantics)

virtual ~StokesCoordinate()

Destructor.

virtual Coordinate::Type type() const

Returns Coordinates::STOKES.

virtual String showType() const

Always returns the String "Stokes".

virtual uInt nPixelAxes() const
virtual uInt nWorldAxes() const

Always returns 1.

virtual Bool toWorld(Vector<Double> &world, const Vector<Double> &pixel) const
virtual Bool toPixel(Vector<Double> &pixel, const Vector<Double> &world) const

Convert a pixel to a world coordinate or vice versa. Returns True if the conversion succeeds, otherwise it returns False and method errorMessage returns an error message. The output vectors are appropriately resized before use.

Bool toPixel(Int &pixel, Stokes::StokesTypes stokes) const
Bool toWorld(Stokes::StokesTypes &stokes, Int pixel) const

Interconvert between pixel and world as a Stokes type.

static Double toWorld (Stokes::StokesTypes stokes)
static Stokes::StokesTypes toWorld (Double world)

Interconvert between world stored as a Double and world stored as a Stokes type. Since these functions are static, any valid Stokes type can be used. The second function returns Stokes::Undefined if world is illegal.

virtual void makePixelRelative (Vector<Double>& pixel) const
virtual void makePixelAbsolute (Vector<Double>& pixel) const
virtual void makeWorldRelative (Vector<Double>& world) const
virtual void makeWorldAbsolute (Vector<Double>& world) const

Make absolute coordinates relative and vice-versa. For the StokesCoordinate relative world coordinates are defined to be the same as absolute world coordinates. Relative pixels do have meaning and are implemented (rel = abs - refPix)

Vector<Int> stokes() const

Get the Stokes values (Stokes::StokesType) that we constructed with into a vector

void setStokes (const Vector<Int> &whichStokes)

Set a new vector of Stokes values (a vector of Stokes::StokesType)

virtual Vector<String> worldAxisNames() const
virtual Vector<Double> referencePixel() const
virtual Matrix<Double> linearTransform() const
virtual Vector<Double> increment() const
virtual Vector<Double> referenceValue() const

Report the value of the requested attribute.

virtual Bool setWorldAxisNames(const Vector<String> &names)
virtual Bool setReferencePixel(const Vector<Double> &refPix)
virtual Bool setLinearTransform(const Matrix<Double> &xform)
virtual Bool setIncrement(const Vector<Double> &inc)
virtual Bool setReferenceValue(const Vector<Double> &refval)

Set the value of the requested attribute. For the StokesCoordinate, these have no effect (always return True) except for setWorldAxisNames.

virtual Bool setWorldAxisUnits(const Vector<String> &units)
virtual Vector<String> worldAxisUnits() const

The set function has no effect as the units must be empty for a StokesCoordinate Always returns True

virtual Bool setWorldMixRanges (const IPosition& shape)
virtual void setDefaultWorldMixRanges ()
virtual Vector<Double> worldMixMin () const
virtual Vector<Double> worldMixMax () const

Set the world min and max ranges, for use in function toMix, for a lattice of the given shape (for this coordinate). The implementation here gives world coordinates at the start and end of the Stokes axis. The output vectors are resized. Returns False if fails (and then setDefaultWorldMixRanges generates the ranges) with a reason in errorMessage(). The setDefaultWorldMixRanges function gives you [-1e99->1e99].

virtual String format(String& units, Coordinate::formatType format, Double worldValue, uInt worldAxis, Bool isAbsolute=True, Bool showAsAbsolute=True, Int precision = -1)

Format a StokesCoordinate world value with the common format interface (refer to the base class Coordinate for basics.

A StokesCoordinate is formatted differently from other Coordinate types. The world value is converted to the character representation as defined by the enum StokesTypes in the class Stokes.

Thus, all other arguments to do with formatting and precision are ignored.

virtual Bool near(const Coordinate& other, Double tol=1e-6) const
virtual Bool near(const Coordinate& other, const Vector<Int>& excludeAxes, Double tol=1e-6) const

Comparison function. Any private Double data members are compared with the specified fractional tolerance. Don't compare on the specified axes in the Coordinate. If the comparison returns False, method errorMessage returns a message about why.

virtual Bool save(RecordInterface &container, const String &fieldName) const

Save the StokesCoordinate into the supplied record using the supplied field name. The field must not exist, otherwise False is returned.

static StokesCoordinate* restore(const RecordInterface &container, const String &fieldName)

Recover the StokesCoordinate from a record. A null pointer means that the restoration did not succeed - probably because fieldName doesn't exist or doesn't contain a CoordinateSystem.

virtual Coordinate *clone() const

Make a copy of the StokesCoordinate using new. The caller is responsible for calling delete.