A TimeFrame is a specialised form of one-dimensional Frame which represents various coordinate systems used to describe positions in time. More...
#include <TimeFrame.h>
Public Types | |
| using | ObjectPtr = std::unique_ptr< AstObject, Deleter > |
| unique pointer holding an AST raw pointer More... | |
Public Member Functions | |
| TimeFrame (std::string const &options="") | |
| Construct a TimeFrame. More... | |
| virtual | ~TimeFrame () |
| TimeFrame (TimeFrame const &)=default | |
| Copy constructor: make a deep copy. More... | |
| TimeFrame (TimeFrame &&)=default | |
| TimeFrame & | operator= (TimeFrame const &)=delete |
| TimeFrame & | operator= (TimeFrame &&)=default |
| std::shared_ptr< TimeFrame > | copy () const |
| Return a deep copy of this object. More... | |
| double | currentTime () const |
| Get the current system time. More... | |
| std::string | getAlignTimeScale () const |
| Get AlignTimeScale: time scale in which to align TimeFrames. More... | |
| double | getLTOffset () const |
| Get LTOffset: the offset of Local Time from UTC, in hours. More... | |
| double | getTimeOrigin () const |
| Get TimeOrigin: the zero point for TimeFrame axis values. More... | |
| std::string | getTimeScale () const |
| Get TimeScale: the timescale used by the TimeFrame. More... | |
| void | setAlignTimeScale (std::string const &scale) |
| Set AlignTimeScale: time scale in which to align TimeFrames. More... | |
| void | setLTOffset (double offset) |
| Set LTOffset: the offset of Local Time from UTC, in hours. More... | |
| void | setTimeOrigin (double origin) |
| Set TimeOrigin: the zero point for TimeFrame axis values. More... | |
| void | setTimeScale (std::string const &scale) |
| Set TimeScale: the timescale used by the TimeFrame. More... | |
| double | angle (PointD const &a, PointD const &b, PointD const &c) const |
| Find the angle at point B between the line joining points A and B, and the line joining points C and B. More... | |
| double | axAngle (PointD const &a, PointD const &b, int axis) const |
| Find the angle, as seen from point A, between the positive direction of a specified axis, and the geodesic curve joining point A to point B. More... | |
| double | axDistance (int axis, double v1, double v2) const |
| Return a signed value representing the axis increment from axis value v1 to axis value v2. More... | |
| double | axOffset (int axis, double v1, double dist) const |
| Return an axis value formed by adding a signed axis increment onto a supplied axis value. More... | |
| std::shared_ptr< FrameSet > | convert (Frame const &to, std::string const &domainlist="") |
| Compute a frameset that describes the conversion between this frame and another frame. More... | |
| double | distance (PointD const &point1, PointD const &point2) const |
| Find the distance between two points whose Frame coordinates are given. More... | |
| std::shared_ptr< FrameSet > | findFrame (Frame const &tmplt, std::string const &domainlist="") |
| Find a coordinate system with specified characteristics. More... | |
| std::string | format (int axis, double value) const |
| Return a string containing the formatted (character) version of a coordinate value for a Frame axis. More... | |
| bool | getActiveUnit () const |
| Get ActiveUnit: pay attention to units when one Frame is used to match another? More... | |
| std::string | getAlignSystem () const |
| Get AlignSystem: the coordinate system used by convert and findFrame to align Frames. More... | |
| double | getBottom (int axis) const |
| Get Bottom for one axis: the lowest axis value to display. More... | |
| int | getDigits () const |
| Get Digits: the default used if no specific value specified for an axis. More... | |
| int | getDigits (int axis) const |
| Get Digits for one axis. More... | |
| bool | getDirection (int axis) const |
| Get Direction for one axis: display axis in conventional direction? More... | |
| std::string | getDomain () const |
| Get Domain: coordinate system domain. More... | |
| double | getDut1 () const |
| Get Dut1: difference between the UT1 and UTC timescale (sec) More... | |
| double | getEpoch () const |
| Get Epoch: Epoch of observation. More... | |
| std::string | getFormat (int axis) const |
| Get Format for one axis: format specification for axis values. More... | |
| std::string | getInternalUnit (int axis) const |
| Get InternalUnit(axis) read-only attribute for one axis: physical units for unformated axis values. More... | |
| std::string | getLabel (int axis) const |
| Get Label(axis) for one axis: axis label. More... | |
| bool | getMatchEnd () const |
| Get MatchEnd: match trailing axes? More... | |
| int | getMaxAxes () const |
| Get MaxAxes: the maximum axes a frame found by findFrame may have. More... | |
| int | getMinAxes () const |
| Get MinAxes: the maximum axes a frame found by findFrame may have. More... | |
| int | getNAxes () const |
| Get NAxes: the number of axes in the frame (i.e. More... | |
| std::string | getNormUnit (int axis) const |
| Get NormUnit(axis) read-only attribute for one frame: normalised physical units for formatted axis values. More... | |
| double | getObsAlt () const |
| Get ObsAlt: Geodetic altitude of observer (m). More... | |
| std::string | getObsLat () const |
| Get ObsLat: Geodetic latitude of observer. More... | |
| std::string | getObsLon () const |
| Get ObsLon: Geodetic longitude of observer. More... | |
| bool | getPermute () const |
| Get Permute: allow axis permutation when used as a template? More... | |
| bool | getPreserveAxes () const |
| Get PreserveAxes: preserve axes? More... | |
| std::string | getSymbol (int axis) const |
| Get Symbol(axis) for one axis: axis symbol. More... | |
| std::string | getSystem () const |
| Get System: coordinate system used to describe positions within the domain. More... | |
| std::string | getTitle () const |
| Get Title: frame title. More... | |
| double | getTop (int axis) const |
| Get Top: the highest axis value to display. More... | |
| std::string | getUnit (int axis) const |
| Get Unit(axis) for one axis: physical units for formatted axis values. More... | |
| std::vector< double > | intersect (std::vector< double > const &a1, std::vector< double > const &a2, std::vector< double > const &b1, std::vector< double > const &b2) const |
| Find the point of intersection between two geodesic curves. More... | |
| std::vector< int > | matchAxes (Frame const &other) const |
| Look for corresponding axes between this frame and another. More... | |
| CmpFrame | under (Frame const &next) const |
Combine this frame with another to form a compound frame (CmpFrame), with the axes of this frame followed by the axes of the next frame. More... | |
| ParallelMap | under (Mapping const &next) const |
| Return a parallel compound mapping containing shallow copies of the original. More... | |
| PointD | norm (PointD value) const |
| Normalise a set of Frame coordinate values which might be unsuitable for display (e.g. More... | |
| PointD | offset (PointD point1, PointD point2, double offset) const |
| Find the point which is offset a specified distance along the geodesic curve between two other points. More... | |
| DirectionPoint | offset2 (PointD const &point1, double angle, double offset) const |
| Find the point which is offset a specified distance along the geodesic curve at a given angle from a specified starting point. More... | |
| void | permAxes (std::vector< int > perm) |
| Permute the order in which a Frame's axes occur. More... | |
| FrameMapping | pickAxes (std::vector< int > const &axes) const |
| Create a new Frame whose axes are copied from an existing Frame along with other Frame attributes, such as its Title. More... | |
| ResolvedPoint | resolve (std::vector< double > const &point1, std::vector< double > const &point2, std::vector< double > const &point3) const |
| Resolve a vector into two orthogonal components. More... | |
| void | setAlignSystem (std::string const &system) |
| Set AlignSystem: the coordinate system used by convert and findFrame to align Frames. More... | |
| void | setBottom (int axis, double bottom) |
| Set Bottom: the lowest axis value to display. More... | |
| void | setDigits (int digits) |
| Set Digits for all axes: number of digits of precision. More... | |
| void | setDigits (int axis, int digits) |
| Set Digits for one axis: number of digits of precision. More... | |
| void | setDirection (bool direction, int axis) |
| Set Direction for one axis: display axis in conventional direction? More... | |
| virtual void | setDomain (std::string const &domain) |
| Set Domain: coordinate system domain. More... | |
| void | setDut1 (double dut1) |
| Set Dut1: difference between the UT1 and UTC timescale (sec) More... | |
| void | setEpoch (double epoch) |
| Set Epoch: Epoch of observation as a double (years) More... | |
| void | setEpoch (std::string const &epoch) |
| Set Epoch: Epoch of observation as a string. More... | |
| void | setFormat (int axis, std::string const &format) |
| Set Format for one axis: format specification for axis values. More... | |
| void | setLabel (int axis, std::string const &label) |
| Set Label(axis) for one axis: axis label. More... | |
| void | setMatchEnd (bool match) |
| Set MatchEnd: match trailing axes? More... | |
| void | setMaxAxes (int maxAxes) |
| Get MaxAxes: the maximum number of axes a frame found by findFrame may have. More... | |
| void | setMinAxes (int minAxes) |
| Get MinAxes: the minimum number of axes a frame found by findFrame may have. More... | |
| void | setObsAlt (double alt) |
| Set ObsAlt: Geodetic altitude of observer (m). More... | |
| void | setObsLat (std::string const &lat) |
| Set ObsLat: frame title. More... | |
| void | setObsLon (std::string const &lon) |
| Set ObsLon: Geodetic longitude of observer. More... | |
| void | setActiveUnit (bool enable) |
| Set ActiveUnit: pay attention to units when one Frame is used to match another? More... | |
| void | setPermute (bool permute) |
| Set Permute: allow axis permutation when used as a template? More... | |
| void | setPreserveAxes (bool preserve) |
| Set PreserveAxes: preserve axes? More... | |
| void | setSymbol (int axis, std::string const &symbol) |
| Set Symbol(axis) for one axis: axis symbol. More... | |
| void | setSystem (std::string const &system) |
| Set System: coordinate system used to describe positions within the domain. More... | |
| void | setTitle (std::string const &title) |
| Set Title: frame title. More... | |
| void | setTop (int axis, double top) |
| Set Top for one axis: the highest axis value to display. More... | |
| void | setUnit (int axis, std::string const &unit) |
| Set Unit(axis) for one axis: physical units for formatted axis values. More... | |
| NReadValue | unformat (int axis, std::string const &str) const |
| Read a formatted coordinate value (given as a character string) for a Frame axis and return the number of characters read and the value. More... | |
| int | getNIn () const |
| Get NIn: the number of input axes. More... | |
| int | getNOut () const |
| Get NOut: the number of output axes. More... | |
| bool | getIsSimple () const |
| Get IsSimple: has the mapping been simplified? More... | |
| bool | isInverted () const |
| Is this an inverted mapping? More... | |
| bool | getIsLinear () const |
| Get IsLinear: is the Mapping linear? More... | |
| bool | getReport () const |
| Get Report: report transformed coordinates to stdout? More... | |
| bool | hasForward () const |
| Is the forward transform available? More... | |
| bool | hasInverse () const |
| Is the inverse transform available? More... | |
| std::shared_ptr< Mapping > | inverted () const |
| Get an inverse mapping. More... | |
| Array2D | linearApprox (PointD const &lbnd, PointD const &ubnd, double tol) const |
| Compute a linear approximation to the forward transformation. More... | |
| SeriesMap | then (Mapping const &next) const |
| Return a series compound mapping this(first(input)) containing shallow copies of the original. More... | |
| double | rate (PointD const &at, int ax1, int ax2) const |
| Evaluate the rate of change of the Mapping with respect to a specified input, at a specified position. More... | |
| void | setReport (bool report) |
| Set Report: report transformed coordinates to stdout? More... | |
| std::shared_ptr< Mapping > | simplified () const |
| Return a simplied version of the mapping (which may be a compound Mapping such as a CmpMap). More... | |
| void | applyForward (ConstArray2D const &from, Array2D const &to) const |
| Perform a forward transformation on 2-D array, putting the results into a pre-allocated 2-D array. More... | |
| Array2D | applyForward (ConstArray2D const &from) const |
| Perform a forward transformation on a 2-D array, returning the results as a new array. More... | |
| std::vector< double > | applyForward (std::vector< double > const &from) const |
| Perform a forward transformation on a vector, returning the results as a new vector. More... | |
| void | applyInverse (ConstArray2D const &from, Array2D const &to) const |
| Perform an inverse transformation on a 2-D array, putting the results into a pre-allocated 2-D array. More... | |
| Array2D | applyInverse (ConstArray2D const &from) const |
| Perform an inverse transformation on a 2-D array, returning the results as a new 2-D array. More... | |
| std::vector< double > | applyInverse (std::vector< double > const &from) const |
| Perform an inverse transformation on a vector, returning the results as a new vector. More... | |
| void | tranGridForward (PointI const &lbnd, PointI const &ubnd, double tol, int maxpix, Array2D const &to) const |
| Transform a grid of points in the forward direction. More... | |
| Array2D | tranGridForward (PointI const &lbnd, PointI const &ubnd, double tol, int maxpix, int nPts) const |
| Transform a grid of points in the inverse direction, returning the results as a new Array2D. More... | |
| void | tranGridInverse (PointI const &lbnd, PointI const &ubnd, double tol, int maxpix, Array2D const &to) const |
| Transform a grid of points in the inverse direction. More... | |
| Array2D | tranGridInverse (PointI const &lbnd, PointI const &ubnd, double tol, int maxpix, int nPts) const |
| Transform a grid of points in the inverse direction. More... | |
| bool | operator== (Object const &rhs) const |
Return True if this and rhs are the equal. More... | |
| bool | operator!= (Object const &rhs) const |
Return True if this and rhs are not equal. More... | |
| void | clear (std::string const &attrib) |
| Clear the values of a specified set of attributes for an Object. More... | |
| bool | hasAttribute (std::string const &attrib) const |
| Does this object have an attribute with the specified name? More... | |
| std::string | getClassName () const |
| Get Class: the name of the class (e.g. More... | |
| std::string | getID () const |
| Get ID: object identification string that is not copied. More... | |
| std::string | getIdent () const |
| Get Ident: object identification string that is copied. More... | |
| int | getNObject () const |
| Get NObject: number of AST objects in existence of the same type as the underlying AST class. More... | |
| int | getObjSize () const |
| Get ObjSize: the in-memory size of the AST object in bytes. More... | |
| int | getRefCount () const |
| Get RefCount: number of active pointers to the underlying AST object. More... | |
| bool | getUseDefs () const |
| Get UseDefs: allow use of default values for Object attributes? More... | |
| void | lock (bool wait) |
| Lock this object for exclusive use by the calling thread. More... | |
| bool | same (Object const &other) const |
| Does this contain the same AST object as another? More... | |
| void | setID (std::string const &id) |
| Set ID: object identification string that is not copied. More... | |
| void | setIdent (std::string const &ident) |
| Set Ident: object identification string that is copied. More... | |
| void | setUseDefs (bool usedefs) |
| Set UseDefs: allow use of default values for Object attributes? More... | |
| void | show (std::ostream &os, bool showComments=true) const |
| Print a textual description the object to an ostream. More... | |
| std::string | show (bool showComments=true) const |
| Return a textual description the object as a string. More... | |
| bool | test (std::string const &attrib) const |
| Has this attribute been explicitly set (and not subsequently cleared)? More... | |
| void | unlock (bool report=false) |
| Unlock this object previously locked using lock, so that other threads can use this object. More... | |
| AstObject const * | getRawPtr () const |
| Get the raw AST pointer. More... | |
| AstObject * | getRawPtr () |
| Get the raw AST pointer. More... | |
Static Public Member Functions | |
| static std::shared_ptr< Object > | fromString (std::string const &str) |
| Construct an Object from a string, using astFromString. More... | |
| template<typename Class > | |
| static std::shared_ptr< Class > | fromAstObject (AstObject *rawObj, bool copy) |
| Given a bare AST object pointer return a shared pointer to an ast::Object of the correct type. More... | |
Protected Member Functions | |
| virtual std::shared_ptr< Object > | copyPolymorphic () const override |
| Return a deep copy of this object. More... | |
| TimeFrame (AstTimeFrame *rawptr) | |
| Construct a TimeFrame from a raw AST pointer. More... | |
| template<typename Class > | |
| std::shared_ptr< Class > | decompose (int i, bool copy) const |
| Return a deep copy of one of the two component mappings. More... | |
| template<typename T , typename AstT > | |
| std::shared_ptr< T > | copyImpl () const |
| Implementation of deep copy. More... | |
| bool | getB (std::string const &attrib) const |
| Get the value of an attribute as a bool. More... | |
| std::string const | getC (std::string const &attrib) const |
| Get the value of an attribute as a string. More... | |
| double | getD (std::string const &attrib) const |
| Get the value of an attribute as a double. More... | |
| float | getF (std::string const &attrib) const |
| Get the value of an attribute as a float. More... | |
| int | getI (std::string const &attrib) const |
| Get the value of an attribute as an int. More... | |
| long int | getL (std::string const &attrib) const |
| Get the value of an attribute as a long int. More... | |
| void | set (std::string const &setting) |
| Assign a set of attribute values, over-riding any previous values. More... | |
| void | setB (std::string const &attrib, bool value) |
| Set the value of an attribute as a bool. More... | |
| void | setC (std::string const &attrib, std::string const &value) |
| Set the value of an attribute as a string. More... | |
| void | setD (std::string const &attrib, double value) |
| Set the value of an attribute as a double. More... | |
| void | setF (std::string const &attrib, float value) |
| Set the value of an attribute as a float. More... | |
| void | setI (std::string const &attrib, int value) |
| Set the value of an attribute as an int. More... | |
| void | setL (std::string const &attrib, long int value) |
| Set the value of an attribute as a long int. More... | |
Static Protected Member Functions | |
| template<typename ShimT , typename AstT > | |
| static std::shared_ptr< ShimT > | makeShim (AstObject *p) |
| Functor to make an astshim instance from a raw AST pointer of the corresponding type. More... | |
Friends | |
| class | Object |
Detailed Description
A TimeFrame is a specialised form of one-dimensional Frame which represents various coordinate systems used to describe positions in time.
A TimeFrame represents a moment in time as either an Modified Julian Date (MJD), a Julian Date (JD), a Besselian epoch or a Julian epoch, as determined by the System attribute. Optionally, a zero point can be specified (using attribute TimeOrigin) which results in the TimeFrame representing time offsets from the specified zero point.
Even though JD and MJD are defined as being in units of days, the TimeFrame class allows other units to be used (via the Unit attribute) on the basis of simple scalings (60 seconds = 1 minute, 60 minutes = 1 hour, 24 hours = 1 day, 365.25 days = 1 year). Likewise, Julian epochs can be described in units other than the usual years. Besselian epoch are always represented in units of (tropical) years.
The TimeScale attribute allows the time scale to be specified (that is, the physical process used to define the rate of flow of time). MJD, JD and Julian epoch can be used to represent a time in any supported time scale. However, Besselian epoch may only be used with the "TT" (Terrestrial Time) time scale. The list of supported time scales includes universal time and siderial time. Strictly, these represent angles rather than time scales, but are included in the list since they are in common use and are often thought of as time scales. When a time value is formatted it can be formated either as a simple floating point value, or as a Gregorian date (see the Format attribute).
Attributes
TimeFrame has the following attributes in addition to those provided by Frame, Mapping and Object
- AlignTimeScale: time scale in which to align TimeFrames.
- LTOffset: the offset of Local Time from UTC, in hours.
- TimeOrigin: the zero point for TimeFrame axis values.
- TimeScale: the timescale used by the TimeFrame.
Several of the Frame attributes inherited by the TimeFrame class refer to a specific axis of the Frame (for instance Unit(axis), Label(axis), etc). Since a TimeFrame is strictly one-dimensional, it allows these attributes to be specified without an axis index. So for instance, "Unit" is allowed in place of "Unit(1)".
Definition at line 80 of file TimeFrame.h.
Member Typedef Documentation
◆ ObjectPtr
|
inherited |
Constructor & Destructor Documentation
◆ TimeFrame() [1/4]
|
inlineexplicit |
Construct a TimeFrame.
- Parameters
-
[in] options Comma-separated list of attribute assignments.
Definition at line 89 of file TimeFrame.h.
◆ ~TimeFrame()
|
inlinevirtual |
Definition at line 94 of file TimeFrame.h.
◆ TimeFrame() [2/4]
|
default |
Copy constructor: make a deep copy.
◆ TimeFrame() [3/4]
|
default |
◆ TimeFrame() [4/4]
|
inlineexplicitprotected |
Construct a TimeFrame from a raw AST pointer.
Definition at line 159 of file TimeFrame.h.
Member Function Documentation
◆ angle()
|
inlineinherited |
Find the angle at point B between the line joining points A and B, and the line joining points C and B.
These lines will in fact be geodesic curves appropriate to the Frame in use. For instance, in SkyFrame, they will be great circles.
- Parameters
-
[in] a the coordinates of the first point [in] b the coordinates of the first second [in] c the coordinates of the first third
- Returns
- The angle in radians, from the line AB to the line CB. If the Frame is 2-dimensional, it will be in the range [-pi, pi], and positive rotation is in the same sense as rotation from the positive direction of axis 2 to the positive direction of axis 1. If the Frame has more than 2 axes, a positive value will always be returned in the range (0, pi].
- Exceptions
-
std::invalid_argument if a,borchave the wrong length
Definition at line 201 of file Frame.h.
◆ applyForward() [1/3]
|
inlineinherited |
Perform a forward transformation on a 2-D array, returning the results as a new array.
- Parameters
-
[in] from input coordinates, with dimensions (nPts, nIn)
- Returns
- the results as a new array with dimensions (nPts, nOut)
Definition at line 268 of file Mapping.h.
◆ applyForward() [2/3]
|
inlineinherited |
◆ applyForward() [3/3]
|
inlineinherited |
Perform a forward transformation on a vector, returning the results as a new vector.
- Parameters
-
[in] from input coordinates as a vector, with axes adjacent, e.g. x0, y0, x1, y1...xn, yn
- Returns
- the results as a new vector
Definition at line 280 of file Mapping.h.
◆ applyInverse() [1/3]
|
inlineinherited |
Perform an inverse transformation on a 2-D array, returning the results as a new 2-D array.
- Parameters
-
[in] from output coordinates, with dimensions (nPts, nOut)
- Returns
- the results as a new array with dimensions (nPts, nIn)
◆ applyInverse() [2/3]
|
inlineinherited |
Perform an inverse transformation on a 2-D array, putting the results into a pre-allocated 2-D array.
- Parameters
-
[in] from input coordinates, with dimensions (nPts, nOut) [out] to transformed coordinates, with dimensions (nPts, nIn)
◆ applyInverse() [3/3]
|
inlineinherited |
◆ axAngle()
Find the angle, as seen from point A, between the positive direction of a specified axis, and the geodesic curve joining point A to point B.
- Parameters
-
[in] a the coordinates of the first point [in] b the coordinates of the second point [in] axis the index of the axis from which the angle is to be measured, where 1 is the first axis
- Returns
- The angle in radians, from the positive direction of the specified axis, to the line AB. If the Frame is 2-dimensional, it will be in the range [-pi/2, +pi/2], and positive rotation is in the same sense as rotation from the positive direction of axis 2 to the positive direction of axis 1. If the Frame has more than 2 axes, a positive value will always be returned in the range (0, pi]
- Exceptions
-
std::invalid_argument if aorbhave the wrong length
Notes:
- The geodesic curve used by this function is the path of shortest distance between two points, as defined by the
distancemethod.
◆ axDistance()
|
inlineinherited |
Return a signed value representing the axis increment from axis value v1 to axis value v2.
For a simple Frame, this is a trivial operation returning the difference between the two axis values. But for other derived classes of Frame (such as a SkyFrame) this is not the case.
- Parameters
-
[in] axis The index of the axis to which the supplied values refer. The first axis has index 1. [in] v1 The first axis value. [in] v2 The second axis value.
- Returns
- The distance from the first to the second axis value.
◆ axOffset()
|
inlineinherited |
Return an axis value formed by adding a signed axis increment onto a supplied axis value.
For a simple Frame, this is a trivial operation returning the sum of the two supplied values. But for other derived classes of Frame (such as a SkyFrame) this is not the case.
- Parameters
-
[in] axis The index of the axis to which the supplied values refer. The first axis has index 1. [in] v1 The original axis value. [in] dist The axis increment to add to the original axis value.
- Returns
- The incremented axis value
◆ clear()
|
inlineinherited |
Clear the values of a specified set of attributes for an Object.
Clearing an attribute cancels any value that has previously been explicitly set for it, so that the standard default attribute value will subsequently be used instead. This also causes the astTest function to return the value zero for the attribute, indicating that no value has been set.
◆ convert()
|
inherited |
Compute a frameset that describes the conversion between this frame and another frame.
If conversion is possible, it returns a shared pointer to a FrameSet which describes the conversion and which may be used (as a Mapping) to transform coordinate values in either direction. Otherwise it returns an empty shared pointer.
The same function may also be used to determine how to convert between two FrameSets (or between a Frame and a FrameSet, or vice versa). This mode is intended for use when (for example) two images have been calibrated by attaching a FrameSet to each. convert might then be used to search for a celestial coordinate system that both images have in common, and the result could then be used to convert between the pixel coordinates of both images – having effectively used their celestial coordinate systems to align them.
When using FrameSets, there may be more than one possible intermediate coordinate system in which to perform the conversion (for instance, two FrameSets might both have celestial coordinates, detector coordinates, pixel coordinates, etc.). A comma-separated list of coordinate system domains may therefore be given which defines a priority order to use when selecting the intermediate coordinate system. The path used for conversion must go via an intermediate coordinate system whose Domain attribute matches one of the domains given. If conversion cannot be achieved using the first domain, the next one is considered, and so on, until success is achieved.
Applicability
-
If the AlignSideBand attribute is non-zero, alignment occurs in the upper sideband expressed within the spectral system and standard of rest given by attributes AlignSystem and
AlignStdOfRest. IfAlignSideBandis zero, the two DSBSpecFrames are aligned as if they were simple SpecFrames (i.e. the SideBand is ignored). -
This function applies to all Frames. Alignment occurs within the coordinate system given by attribute AlignSystem.
-
If either this object or
tois a FrameSet, then this method will attempt to convert from the coordinate system described by the current Frame of the "from" FrameSet to that described by the current Frame of the "to" FrameSet.To achieve this, it will consider all of the Frames within each FrameSet as a possible way of reaching an intermediate coordinate system that can be used for the conversion. There is then the possibility that more than one conversion path may exist and, unless the choice is sufficiently restricted by the "domainlist" string, the sequence in which the Frames are considered can be important. In this case, the search for a conversion path proceeds as follows:
- Each field in the "domainlist" string is considered in turn.
- The Frames within each FrameSet are considered in a specific order: (1) the base Frame is always considered first, (2) after this come all the other Frames in Frame-index order (but omitting the base and current Frames), (3) the current Frame is always considered last. However, if either FrameSet's Invert attribute is set to a non-zero value (so that the FrameSet is inverted), then its Frames are considered in reverse order. (Note that this still means that the base Frame is considered first and the current Frame last, because the Invert value will also cause these Frames to swap places.)
- All source Frames are first considered (in the appropriate order) for conversion to the first destination Frame. If no suitable intermediate coordinate system emerges, they are then considered again for conversion to the second destination Frame (in the appropriate order), and so on.
- Generally, the first suitable intermediate coordinate system found is used. However, the overall Mapping between the source and destination coordinate systems is also examined. Preference is given to cases where both the forward and inverse transformations are defined. If only one transformation is defined, the forward one is preferred.
- If the domain of the intermediate coordinate system matches the current "domainlist" field, the conversion path is accepted. Otherwise, the next "domainlist" field is considered and the process repeated.
If conversion is possible, the Base attributes of the two FrameSets will be modified on exit to identify the Frames used to access the intermediate coordinate system which was finally accepted.
Note that it is possible to force a particular Frame within a FrameSet to be used as the basis for the intermediate coordinate system, if it is suitable, by (a) focussing attention on it by specifying its domain in the "domainlist" string, or (b) making it the base Frame, since this is always considered first.
-
Alignment occurs within the spectral system and standard of rest given by attributes AlignSystem and
AlignStdOfRest. -
Alignment occurs within the time system and time scale given by attributes AlignSystem and
AlignTimeScale.
Examples
auto cvt = a.convert(b)Obtain a FrameSet that converts between the coordinate systems represented by "a" and "b" (assumed to be Frames).
auto cvt = SkyFrame().convert(SkyFrame("Equinox=2005"))Create a FrameSet which describes precession in the default FK5 celestial coordinate system between equinoxes J2000 (also the default) and J2005. The returned "cvt" FrameSet may be used to apply this precession correction to any number of coordinate values given in radians.
Note that the returned FrameSet also contains information about how to format coordinate values. This means that setting its Report attribute to 1 is a simple way to obtain printed output (formatted in sexagesimal notation) to show the coordinate values before and after conversion.
auto cvt = a.convert(b, "sky,detector,")Create a FrameSet that converts between the coordinate systems represented by the current Frames of "a" and "b" (now assumed to be FrameSets), via the intermediate "SKY" coordinate system. This, by default, is the Domain associated with a celestial coordinate system represented by a SkyFrame.
If this fails (for example, because either FrameSet lacks celestial coordinate information), then the user-defined "DETECTOR" coordinate system is used instead. If this also fails, then all other possible ways of achieving conversion are considered before giving up.
The returned "cvt" FrameSet describes the conversion.
The Base attributes of the two FrameSet will be set by `ref convert to indicate which of their Frames was used for the intermediate coordinate system. This means that you can subsequently determine which coordinate system was used by enquiring the Domain attribute of either base Frame.
- Parameters
-
[in,out] to A Frame which represents the "destination" coordinate system. This is the coordinate system into which you wish to convert your coordinates. If a FrameSet is given, its current Frame (as determined by its Current attribute) is taken to describe the destination coordinate system. Note that the Base attribute of this FrameSet may be modified by this function to indicate which intermediate coordinate system was used. [in] domainlist A string containing a comma-separated list of Frame domains. This may be used to define a priority order for the different intermediate coordinate systems that might be used to perform the conversion. The function will first try to obtain a conversion by making use only of an intermediate coordinate system whose Domain attribute matches the first domain in this list. If this fails, the second domain in the list will be used, and so on, until conversion is achieved. A blank domain (e.g. two consecutive commas) indicates that all coordinate systems should be considered, regardless of their domains.
- Returns
- A FrameSet which describes the conversion and contains two Frames, or an empty shared pointer if the conversion is not possible. Frame number 1 (its base Frame) will describe the source coordinate system, corresponding to the "from" parameter. Frame number 2 (its current Frame) will describe the destination coordinate system, corresponding to the "to" parameter. The Mapping which inter-relates these two Frames will perform the required conversion between their respective coordinate systems. Note that a FrameSet may be used both as a Mapping and as a Frame. If the result is used as a Mapping then it provides a means of converting coordinates from the source to the destination coordinate system (or vice versa if its inverse transformation is selected). If it is used as a Frame, its attributes will describe the destination coordinate system.
Notes
- The Mapping represented by the returned FrameSet results in alignment taking place in the coordinate system specified by the AlignSystem attribute of the "to" Frame. See the description of the AlignSystem attribute for further details.
- When aligning (say) two images, which have been calibrated by attaching FrameSets to them, it is usually necessary to convert between the base Frames (representing "native" pixel coordinates) of both FrameSets. This may be achieved by obtaining the inverses of the FrameSets (using inverted).
Definition at line 31 of file Frame.cc.
◆ copy()
|
inline |
Return a deep copy of this object.
Definition at line 103 of file TimeFrame.h.
◆ copyImpl()
|
inlineprotectedinherited |
◆ copyPolymorphic()
|
inlineoverrideprotectedvirtual |
Return a deep copy of this object.
This is called by copy.
Each subclass must override this method. The standard implementation is:
for example Frame implements this as:
Reimplemented from ast::Frame.
Definition at line 154 of file TimeFrame.h.
◆ currentTime()
|
inline |
Get the current system time.
- Returns
- the current system time, as specified by the frame's attributes
System,TimeOrigin,LTOffset,TimeScale, andUnit.
- Exceptions
-
std::runtime_error if the frame has a TimeScalevalue which cannot be converted to TAI (e.g. " angular" systems such as UT1, GMST, LMST and LAST).
Notes:
- Resolution is one second.
- This method assumes that the system time (returned by the C
time()function) follows the POSIX standard, representing a continuous monotonic increasing count of SI seconds since the epoch00:00:00 UTC 1 January 1970 AD(equivalent to TAI with a constant offset). - Any inaccuracy in the system clock will be reflected in the value returned by this function.
Definition at line 123 of file TimeFrame.h.
◆ decompose()
|
protectedinherited |
Return a deep copy of one of the two component mappings.
This is intended to be exposed by classes that need it (e.g. CmpMap, CmpFrame and TranMap) as operator[].
- Parameters
-
[in] i Index: 0 for the first mapping, 1 for the second [in] copy If true make a deep copy, else a shallow copy
- Exceptions
-
std::invalid_argument if iis not 0 or 1.std::runtime_error if this mapping is not a compound mapping.
Definition at line 64 of file Mapping.cc.
◆ distance()
Find the distance between two points whose Frame coordinates are given.
The distance calculated is that along the geodesic curve that joins the two points. For example, in a basic Frame, the distance calculated will be the Cartesian distance along the straight line joining the two points. For a more specialised Frame describing a sky coordinate system, however, it would be the distance along the great circle passing through two sky positions.
- Parameters
-
[in] point1 The coordinates of the first point. [in] point2 The coordinates of the second point.
- Returns
- The distance between the two points.
Definition at line 474 of file Frame.h.
◆ findFrame()
|
inherited |
Find a coordinate system with specified characteristics.
Use a "template" Frame to search another Frame (or FrameSet) to identify a coordinate system which has a specified set of characteristics. If a suitable coordinate system can be found, the function returns a pointer to a FrameSet which describes the required coordinate system and how to convert coordinates to and from it.
This function is provided to help answer general questions about coordinate systems, such as typically arise when coordinate information is imported into a program as part of an initially unknown dataset. For example:
- Is there a wavelength scale?
- Is there a 2-dimensional coordinate system?
- Is there a celestial coordinate system?
- Can I plot the data in ecliptic coordinates?
You can also use this function as a means of reconciling a user's preference for a particular coordinate system (for example, what type of axes to draw) with what is actually possible given the coordinate information available.
To perform a search, you supply a "target" Frame (or FrameSet) which represents the set of coordinate systems to be searched. If a basic Frame is given as the target, this set of coordinate systems consists of the one described by this Frame, plus all other "virtual" coordinate systems which can potentially be reached from it by applying built-in conversions (for example, any of the celestial coordinate conversions known to the AST library would constitute a "built-in" conversion). If a FrameSet is given as the target, the set of coordinate systems to be searched consists of the union of those represented by all the individual Frames within it.
To select from this large set of possible coordinate systems, you supply a "template" Frame which is an instance of the type of Frame you are looking for. Effectively, you then ask the function to "find a coordinate system that looks like this".
You can make your request more or less specific by setting attribute values for the template Frame. If a particular attribute is set in the template, then the function will only find coordinate systems which have exactly the same value for that attribute. If you leave a template attribute un-set, however, then the function has discretion about the value the attribute should have in any coordinate system it finds. The attribute will then take its value from one of the actual (rather than virtual) coordinate systems in the target. If the target is a FrameSet, its Current attribute will be modified to indicate which of its Frames was used for this purpose.
The result of this process is a coordinate system represented by a hybrid Frame which acquires some attributes from the template (but only if they were set) and the remainder from the target. This represents the "best compromise" between what you asked for and what was available. A Mapping is then generated which converts from the target coordinate system to this hybrid one, and the returned FrameSet encapsulates all of this information.
Applicability to Subclasses
-
If the target is a FrameSet, the possibility exists that several of the Frames within it might be matched by the template. Unless the choice is sufficiently restricted by the "domainlist" string, the sequence in which Frames are searched can then become important. In this case, the search proceeds as follows:
- Each field in the "domainlist" string is considered in turn.
- An attempt is made to match the template to each of the target's Frames in the order: (1) the current Frame (2) the base Frame (3) each remaining Frame in the order of being added to the target FrameSet
- Generally, the first match found is used. However, the Mapping between the target coordinate system and the resulting Frame is also examined. Preference is given to cases where both the forward and inverse transformations are defined. If only one transformation is defined, the forward one is preferred.
- If a match is found and the domain of the resulting Frame also matches the current "domainlist" field, it is accepted. Otherwise, the next "domainlist" field is considered and the process repeated.
If a suitable coordinate system is found, then the FrameSet's Current attribute will be modified to indicate which Frame was used to obtain attribute values which were not specified by the template. This Frame will, in some sense, represent the "closest" non-virtual coordinate system to the one you requested.
Examples
auto result = target.findFrame(ast::Frame(3))Search for a 3-dimensional coordinate system in the target Frame (or FrameSet). No attributes have been set in the template Frame (created by ast::Frame), so no restriction has been placed on the required coordinate system, other than that it should have 3 dimensions. The first suitable Frame found will be returned as part of the "result" FrameSet.
auto result = target.findFrame(astSkyFrame())Search for a celestial coordinate system in the target Frame (or FrameSet). The type of celestial coordinate system is unspecified, so astFindFrame will return the first one found as part of the "result" FrameSet. If the target is a FrameSet, then its Current attribute will be updated to identify the Frame that was used.
auto result = target.findFrame(astSkyFrame("MaxAxes=100"))This is like the last example, except that in the event of the target being a CmpFrame, the component Frames encapsulated by the CmpFrame will be searched for a SkyFrame. If found, the returned Mapping will included a PermMap which selects the required axes from the target CmpFrame.
This is acomplished by setting the MaxAxes attribute of the template SkyFrame to a large number (larger than or equal to the number of axes in the target CmpFrame). This allows the SkyFrame to be used as a match for Frames containing from 2 to 100 axes.
auto result = target.findFrame(astSkyFrame("System=FK5"))Search for an equatorial (FK5) coordinate system in the target. The
Equinoxvalue for the coordinate system has not been specified, so will be obtained from the target. If the target is a FrameSet, itsCurrentattribute will be updated to indicate which SkyFrame was used to obtain this value.auto result = target.findFrame(astFrame(2), "sky,pixel,")Search for a 2-dimensional coordinate system in the target. Initially, a search is made for a suitable coordinate system whose Domain attribute has the value "SKY". If this search fails, a search is then made for one with the domain "PIXEL". If this also fails, then any 2-dimensional coordinate system is returned as part of the "result" FrameSet.
Only if no 2-dimensional coordinate systems can be reached by applying built-in conversions to any of the Frames in the target will the search fail.
auto result = target.findFrame(astFrame(1, "Domain=WAVELENGTH"))Searches for any 1-dimensional coordinate system in the target which has the domain "WAVELENGTH".
auto result = target.findFrame(astFrame(1), "wavelength")This example has exactly the same effect as that above. It illustrates the equivalence of the template's Domain attribute and the fields in the "domainlist" string.
auto result = target.findFrame(Frame(1, "MaxAxes=3"))This is a more advanced example which will search for any coordinate system in the target having 1, 2 or 3 dimensions. The Frame returned (as part of the "result" FrameSet) will always be 1-dimensional, but will be related to the coordinate system that was found by a suitable Mapping (e.g. a PermMap) which simply extracts the first axis.
If we had wanted a Frame representing the actual (1, 2 or 3-dimensional) coordinate system found, we could set the PreserveAxes attribute to a non-zero value in the template.
auto result = target.findFrame(SkyFrame("Permute=0"))Search for any celestial coordinate system in the target, but only finds one if its axes are in the conventional (longitude,latitude) order and have not been permuted (e.g. with astPermAxes).
More on Using Templates
A Frame (describing a coordinate system) will be found by this function if (a) it is "matched" by the template you supply, and (b) the value of its Domain attribute appears in the "domainlist" string (except that a blank field in this string permits any domain). A successful match by the template depends on a number of criteria, as outlined below:
- In general, a template will only match another Frame which belongs to the same class as the template, or to a derived (more specialised) class. For example, a SkyFrame template will match any other SkyFrame, but will not match a basic Frame. Conversely, a basic Frame template will match any class of Frame.
- The exception to this is that a Frame of any class can be used to match a CmpFrame, if that CmpFrame contains a Frame of the same class as the template. Note however, the MaxAxes and MinAxes attributes of the template must be set to suitable values to allow it to match the CmpFrame. That is, the MinAxes attribute must be less than or equal to the number of axes in the target, and the MaxAxes attribute must be greater than or equal to the number of axes in the target.
- If using a CmpFrame as a template frame, the MinAxes and MaxAxes for the template are determined by the MinAxes and MaxAxes values of the component Frames within the template. So if you want a template CmpFrame to be able to match Frames with different numbers of axes, then you must set the MaxAxes and/or MinAxes attributes in the component template Frames, before combining them together into the template CmpFrame.
- If a template has a value set for any of its main attributes, then it will only match Frames which have an identical value for that attribute (or which can be transformed, using a built-in conversion, so that they have the required value for that attribute). If any attribute in the template is un-set, however, then Frames are matched regardless of the value they may have for that attribute. You may therefore make a template more or less specific by choosing the attributes for which you set values. This requirement does not apply to 'descriptive' attributes such as titles, labels, symbols, etc.
- An important application of this principle involves the Domain attribute. Setting the Domain attribute of the template has the effect of restricting the search to a particular type of Frame (with the domain you specify). Conversely, if the Domain attribute is not set in the template, then the domain of the Frame found is not relevant, so all Frames are searched. Note that the "domainlist" string provides an alternative way of restricting the search in the same manner, but is a more convenient interface if you wish to search automatically for another domain if the first search fails.
- Normally, a template will only match a Frame which has the same number of axes as itself. However, for some classes of template, this default behaviour may be changed by means of the MinAxes, MaxAxes and MatchEnd attributes. In addition, the behaviour of a template may be influenced by its Permute and PreserveAxes attributes, which control whether it matches Frames whose axes have been permuted, and whether this permutation is retained in the Frame which is returned (as opposed to returning the axes in the order specified in the template, which is the default behaviour). You should consult the descriptions of these attributes for details of this more advanced use of templates.
- Parameters
-
[in,out] tmplt Template Frame, which should be an instance of the type of Frame you wish to find. If you wanted to find a Frame describing a celestial coordinate system, for example, then you might use a SkyFrame here. See the "Examples" section for more ideas. [in] domainlist String containing a comma-separated list of Frame domains. This may be used to establish a priority order for the different types of coordinate system that might be found. The function will first try to find a suitable coordinate system whose Domain attribute equals the first domain in this list. If this fails, the second domain in the list will be used, and so on, until a result is obtained. A blank domain (e.g. two consecutive commas) indicates that any coordinate system is acceptable (subject to the template) regardless of its domain. This list is case-insensitive and all white space is ignored. If you do not wish to restrict the domain in this way, you should supply an empty string.
- Returns
- A std::shared_ptr<FrameSet> which contains the Frame found and a description of how to convert to (and from) the coordinate system it represents. If the Frame is not found then return a null pointer.
This FrameSet will contain two Frames. Frame number 1 (its base Frame) represents the target coordinate system and will be the same as the (base Frame of the) target. Frame number 2 (its current Frame) will be a Frame representing the coordinate system which the function found. The Mapping which inter-relates these two Frames will describe how to convert between their respective coordinate systems. Note that a FrameSet may be used both as a Mapping and as a Frame. If the result is used as a Mapping, then it provides a means of converting coordinates from the target coordinate system into the new coordinate system that was found (and vice versa if its inverse transformation is selected). If it is used as a Frame, its attributes will describe the new coordinate system.
Notes
- This method is not const because if called on a FrameSet then the BASE frame of the FrameSet may be changed. No other kind of frame will be altered.
- Similarly the
tmplargument is not const because if it is a FrameSet then the BASE frame of the template may be changed. No other kind of frame will be altered. - The Mapping represented by the returned FrameSet results in alignment taking place in the coordinate system specified by the AlignSystem attribute of the "template" Frame. See the description of the AlignSystem for further details.
- Beware of setting the
Domainattribute of the template and then using a "domainlist" string which does not include the template's domain (or a blank field). If you do so, no coordinate system will be found.
Definition at line 41 of file Frame.cc.
◆ format()
|
inlineinherited |
Return a string containing the formatted (character) version of a coordinate value for a Frame axis.
The formatting applied is determined by the Frame's attributes and, in particular, by any Format attribute string that has been set for the axis. A suitable default format (based on the Digits attribute value) will be applied if necessary.
- Parameters
-
[in] axis The number of the Frame axis for which formatting is to be performed (axis numbering starts at 1 for the first axis). [in] value The coordinate value to be formatted.
Definition at line 782 of file Frame.h.
◆ fromAstObject()
|
staticinherited |
Given a bare AST object pointer return a shared pointer to an ast::Object of the correct type.
The returned object takes ownership of the pointer. This is almost always what you want, for instance astDecompose returns shallow copies of the internal pointers.
- Template Parameters
-
Class The class of the returned shared pointer. (The actual class will be the correct class of rawPtr.)
- Parameters
-
[in] rawObj A bare AST object pointer [in] copy If True then make a deep copy of the pointer (and free the original)
Definition at line 138 of file Object.cc.
◆ fromString()
|
inlinestaticinherited |
◆ getActiveUnit()
|
inlineinherited |
◆ getAlignSystem()
|
inlineinherited |
Get AlignSystem: the coordinate system used by convert and findFrame to align Frames.
Definition at line 802 of file Frame.h.
◆ getAlignTimeScale()
|
inline |
Get AlignTimeScale: time scale in which to align TimeFrames.
Definition at line 130 of file TimeFrame.h.
◆ getB()
|
inlineprotectedinherited |
Get the value of an attribute as a bool.
If possible, the attribute value is converted to the type you request.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ getBottom()
|
inlineinherited |
Get Bottom for one axis: the lowest axis value to display.
Definition at line 807 of file Frame.h.
◆ getC()
|
inlineprotectedinherited |
Get the value of an attribute as a string.
If possible, the attribute value is converted to the type you request.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
Definition at line 361 of file Object.h.
◆ getClassName()
|
inlineinherited |
Get Class: the name of the class (e.g.
Note: if AST returns "CmpMap" then the name will be changed to "SeriesMap" or "ParallelMap", as appropriate.
Definition at line 139 of file Object.h.
◆ getD()
|
inlineprotectedinherited |
Get the value of an attribute as a double.
If possible, the attribute value is converted to the type you request.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ getDigits() [1/2]
|
inlineinherited |
Get Digits: the default used if no specific value specified for an axis.
Definition at line 812 of file Frame.h.
◆ getDigits() [2/2]
|
inlineinherited |
◆ getDirection()
|
inlineinherited |
Get Direction for one axis: display axis in conventional direction?
Definition at line 822 of file Frame.h.
◆ getDomain()
|
inlineinherited |
◆ getDut1()
|
inlineinherited |
◆ getEpoch()
|
inlineinherited |
◆ getF()
|
inlineprotectedinherited |
Get the value of an attribute as a float.
If possible, the attribute value is converted to the type you request.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ getFormat()
|
inlineinherited |
◆ getI()
|
inlineprotectedinherited |
Get the value of an attribute as an int.
If possible, the attribute value is converted to the type you request.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ getID()
|
inlineinherited |
◆ getIdent()
|
inlineinherited |
◆ getInternalUnit()
|
inlineinherited |
Get InternalUnit(axis) read-only attribute for one axis: physical units for unformated axis values.
Definition at line 848 of file Frame.h.
◆ getIsLinear()
|
inlineinherited |
◆ getIsSimple()
|
inlineinherited |
◆ getL()
|
inlineprotectedinherited |
Get the value of an attribute as a long int.
If possible, the attribute value is converted to the type you request.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ getLabel()
|
inlineinherited |
◆ getLTOffset()
|
inline |
Get LTOffset: the offset of Local Time from UTC, in hours.
Definition at line 133 of file TimeFrame.h.
◆ getMatchEnd()
|
inlineinherited |
◆ getMaxAxes()
|
inlineinherited |
◆ getMinAxes()
|
inlineinherited |
◆ getNAxes()
|
inlineinherited |
◆ getNIn()
|
inlineinherited |
◆ getNObject()
|
inlineinherited |
◆ getNormUnit()
|
inlineinherited |
Get NormUnit(axis) read-only attribute for one frame: normalised physical units for formatted axis values.
Definition at line 882 of file Frame.h.
◆ getNOut()
|
inlineinherited |
◆ getObjSize()
|
inlineinherited |
◆ getObsAlt()
|
inlineinherited |
◆ getObsLat()
|
inlineinherited |
◆ getObsLon()
|
inlineinherited |
◆ getPermute()
|
inlineinherited |
◆ getPreserveAxes()
|
inlineinherited |
◆ getRawPtr() [1/2]
|
inlineinherited |
◆ getRawPtr() [2/2]
|
inlineinherited |
◆ getRefCount()
|
inlineinherited |
◆ getReport()
|
inlineinherited |
◆ getSymbol()
|
inlineinherited |
◆ getSystem()
|
inlineinherited |
◆ getTimeOrigin()
|
inline |
Get TimeOrigin: the zero point for TimeFrame axis values.
Definition at line 136 of file TimeFrame.h.
◆ getTimeScale()
|
inline |
◆ getTitle()
|
inlineinherited |
◆ getTop()
|
inlineinherited |
◆ getUnit()
|
inlineinherited |
Get Unit(axis) for one axis: physical units for formatted axis values.
Definition at line 933 of file Frame.h.
◆ getUseDefs()
|
inlineinherited |
◆ hasAttribute()
|
inlineinherited |
◆ hasForward()
|
inlineinherited |
Is the forward transform available?
- Note
- This gets the TranForward attribute, but is named
hasForwardinstead ofgetTranForwardfor clarity, since it does not return a transform.
Definition at line 114 of file Mapping.h.
◆ hasInverse()
|
inlineinherited |
Is the inverse transform available?
- Note
- This gets the TranInverse attribute, but is named
hasInverseinstead ofgetTranInversefor clarity, since it does not return a transform.
Definition at line 123 of file Mapping.h.
◆ intersect()
|
inherited |
Find the point of intersection between two geodesic curves.
For example, in a basic Frame, it will find the point of intersection between two straight lines. But for a SkyFrame it will find an intersection of two great circles.
- Warning
- This method can only be used with 2-dimensional Frames.
- Parameters
-
[in] a1 Coordinates of the first point on the first geodesic curve. [in] a2 Coordinates of the second point on the first geodesic curve. [in] b1 Coordinates of the first point on the second geodesic curve. [in] b2 Coordinates of the second point on the second geodesic curve.
- Returns
- the point of intersection between the two geodesic curves.
- Exceptions
-
std::runtime_error if the frame is not 2-dimensional
Notes
- For a SkyFrame each curve will be a great circle, and in general each pair of curves will intersect at two diametrically opposite points on the sky. The returned position is the one which is closest to point
a1. - This method will return
nancoordinate values if any of the input coordinates is invalid, or if the two points defining either geodesic are coincident, or if the two curves do not intersect. - The geodesic curve used by this method is the path of shortest distance between two points, as defined by distance
Definition at line 51 of file Frame.cc.
◆ inverted()
|
inherited |
Get an inverse mapping.
An inverse mapping is a deep copy of a mapping whose Invert attribute has been toggled, as indicated by isInverted. This swaps the meaning of "input" and "output", and of "forward" and "inverse". Thus it swaps the behavior of applyForward and applyInverse, getNIn and getNOut, hasForward and hasInverse and so on.
Note that the inverse mapping contains exactly the same model coefficients as the original, but they are used by applyInverse instead of applyForward. Thus for example if a ZoomMap has a zoom factor of 4.0 then its inverse also reports a zoom factor of 4.0 (despite behaving like an uninverted ZoomMap with zoom factor of 0.25).
Definition at line 41 of file Mapping.cc.
◆ isInverted()
|
inlineinherited |
◆ linearApprox()
|
inherited |
Compute a linear approximation to the forward transformation.
- Parameters
-
[in] lbnd Input point defining the lower bounds of the box over which the linear approximation is computed. [in] ubnd Input point defining the upper bounds of the box over which the linear approximation is computed. [in] tol The maximum permitted deviation from linearity, expressed as apositive Cartesian displacement in the output coordinate space. If a linear fit to the forward transformation of the Mapping deviates from the true transformation by more than this amount at any point which is tested, then raise an exception.
- Returns
- The co-efficients of the linear approximation to the specified transformation, as an 1 + nIn x nOut array. The first index is [constant, gradiant for input 1, gradiant for input 2...] and the second index is [output 1, output 2, ...]. For example, if the Mapping has 2 inputs and 3 outputs then the coefficients are:
X_out = fit[0, 0] + fit[1, 0] X_in + fit[2, 0] Y_in Y_out = fit[0, 1] + fit[1, 1] X_in + fit[2, 1] Y_in Z_out = fit[0, 2] + fit[1, 2] X_in + fit[2, 2] Y_in
- Exceptions
-
std::runtime_error if the forward transformation cannot be modeled to within the specified tol.
Definition at line 49 of file Mapping.cc.
◆ lock()
|
inlineinherited |
Lock this object for exclusive use by the calling thread.
The thread-safe public interface to AST is designed so that an error is reported if any thread attempts to use an Object that it has not previously locked for its own exclusive use using this function. When an Object is created, it is initially locked by the thread that creates it, so newly created objects do not need to be explicitly locked. However, if an Object pointer is passed to another thread, the original thread must first unlock it (using astUnlock) and the new thread must then lock it (using astLock) before the new thread can use the Object.
- Parameters
-
[in] wait If the Object is curently locked by another thread then this function will either report an error or block. If a non-zero value is supplied for "wait", the calling thread waits until the object is available for it to use. Otherwise, an error is reported and the function returns immediately without locking the Object.
Notes
- The Locked object will belong to the current AST context.
- This function returns without action if the Object is already locked by the calling thread.
- If simultaneous use of the same object is required by two or more threads, Object::copy should be used to to produce a deep copy of the Object for each thread. Each copy should then be unlocked by the parent thread (i.e. the thread that created the copy), and then locked by the child thread (i.e. the thread that wants to use the copy).
- This function returns without action if the AST library has been built without POSIX thread support (i.e. the "-with-pthreads" option was not specified when running the "configure" script).
◆ makeShim()
|
inlinestaticprotectedinherited |
Functor to make an astshim instance from a raw AST pointer of the corresponding type.
- Template Parameters
-
ShimT Output astshim class AstT Output AST class
◆ matchAxes()
|
inlineinherited |
Look for corresponding axes between this frame and another.
- Parameters
-
[in] other The other frame
- Returns
- The indices of the axes (within this Frame) that correspond to each axis within
other. Axis indices start at 1. A value of zero will be stored in the returned array for each axis inotherthat has no corresponding axis in this frame. The number of elements in the array will be the number of axes inother.
Notes
- Corresponding axes are identified by the fact that a
Mappingcan be found between them usingfindFrameorconvert. Thus, "corresponding axes" are not necessarily identical. For instance,SkyFrameaxes will match even if they describe different celestial coordinate systems.
Definition at line 985 of file Frame.h.
◆ norm()
Normalise a set of Frame coordinate values which might be unsuitable for display (e.g.
may lie outside the expected range) into a set of acceptable values suitable for display.
- Parameters
-
[in] value A point in the space which the Frame describes.
- Returns
- Normalized version of
value. If any axes ofvaluelie outside the expected range for the Frame, the corresponding returned value is changed to a acceptable (normalised) value. Otherwise, the axes ofvalueare returned unchanged.
Notes
- For some classes of Frame, whose coordinate values are not constrained, this function will always return the input unchanged. However, for Frames whose axes represent cyclic quantities (such as angles or positions on the sky), the output coordinates will typically be wrapped into an appropriate standard range, such as [0, 2 pi].
- The NormMap class is a Mapping which can be used to normalise a set of points using the
normfunction of a specified Frame. - It is intended to be possible to put any set of coordinates into a form suitable for display by using this function to normalise them, followed by appropriate formatting (using astFormat).
Definition at line 1045 of file Frame.h.
◆ offset()
Find the point which is offset a specified distance along the geodesic curve between two other points.
For example, in a basic Frame, this offset will be along the straight line joining two points. For a more specialised Frame describing a sky coordinate system, however, it would be along the great circle passing through two sky positions.
- Parameters
-
[in] point1 The point marking the start of the geodesic curve. [in] point2 The point marking the end of the geodesic curve. [in] offset The required offset from the first point along the geodesic curve. If this is positive, it will be towards the second point. If it is negative, it will be in the opposite direction. This offset need not imply a position lying between the two points given, as the curve will be extrapolated if necessary.
- Returns
- the offset point
Notes:
- The geodesic curve used by this function is the path of shortest distance between two points, as defined by the
distancefunction.
- Exceptions
-
std::invalid_argument if: - point1 or point2 is the wrong length
Definition at line 1075 of file Frame.h.
◆ offset2()
|
inlineinherited |
Find the point which is offset a specified distance along the geodesic curve at a given angle from a specified starting point.
This can only be used with 2-dimensional Frames.
For example, in a basic Frame, this offset will be along the straight line joining two points. For a more specialised Frame describing a sky coordinate system, however, it would be along the great circle passing through two sky positions.
- Parameters
-
[in] point1 The point marking the start of the geodesic curve. [in] angle The angle (in radians) from the positive direction of the second axis, to the direction of the required position, as seen from the starting position. Positive rotation is in the sense of rotation from the positive direction of axis 2 to the positive direction of axis 1. [in] offset The required offset from the first point along the geodesic curve. If this is positive, it will be in the direction of the given angle. If it is negative, it will be in the opposite direction.
- Returns
- a DirectionPoint containing:
- The direction of the geodesic curve at the end point. That is, the angle (in radians) between the positive direction of the second axis and the continuation of the geodesic curve at the requested end point. Positive rotation is in the sense of rotation from the positive direction of axis 2 to the positive direction of axis 1.
- The offset point.
- Exceptions
-
std::invalid_argument if - frame does not have naxes = 2
- point1 or point2 are the wrong length, or point1 has any
AST__BADvalues
Notes
- The geodesic curve used by this function is the path of shortest distance between two points, as defined by the astDistance function
Definition at line 1117 of file Frame.h.
◆ operator!=()
|
inlineinherited |
◆ operator=() [1/2]
◆ operator=() [2/2]
◆ operator==()
|
inherited |
Return True if this and rhs are the equal.
For two objects be equal, they both must have the same attributes and all contained objects must be equal.
Definition at line 85 of file Object.cc.
◆ permAxes()
|
inlineinherited |
Permute the order in which a Frame's axes occur.
- Parameters
-
[in] perm A list of axes in their new order, using the current axis numbering. Axis numbers start at 1 for the first axis. Only genuine permutations of the axis order are permitted, so each axis must be referenced exactly once.
When used on a FrameSet, the axes of the current frame are permuted and all connecting mappings are updated accordingly, so that current behavior is preserved (except for the new axis order for output data).
Definition at line 1138 of file Frame.h.
◆ pickAxes()
|
inherited |
Create a new Frame whose axes are copied from an existing Frame along with other Frame attributes, such as its Title.
Any number (zero or more) of the original Frame's axes may be copied, in any order, and additional axes with default attributes may also be included in the new Frame.
- Parameters
-
[in] axes the axes to be copied. These should be given in the order required in the new Frame, using the axis numbering in the original Frame (which starts at 1 for the first axis). Axes may be selected in any order, but each may only be used once. If additional (default) axes are also to be included, the corresponding elements of this array should be set to zero.
- Returns
- a FrameMapping containing:
Definition at line 68 of file Frame.cc.
◆ rate()
|
inlineinherited |
Evaluate the rate of change of the Mapping with respect to a specified input, at a specified position.
The result is estimated by interpolating the function using a fourth order polynomial in the neighbourhood of the specified position. The size of the neighbourhood used is chosen to minimise the RMS residual per unit length between the interpolating polynomial and the supplied Mapping function. This method produces good accuracy but can involve evaluating the Mapping 100 or more times.
- Parameters
-
[in] at The input position at which the rate of change is to be evaluated. [in] ax1 The index of the output for which the rate of change is to be found (1 for first output). [in] ax2 The index of the input which is to be varied in order to find the rate of change (1 for the first input).
- Returns
- The rate of change of Mapping output
ax1with respect to inputax2, evaluated atat, ornanif the value cannot be calculated.
Definition at line 215 of file Mapping.h.
◆ resolve()
|
inherited |
Resolve a vector into two orthogonal components.
The vector from point 1 to point 2 is used as the basis vector. The vector from point 1 to point 3 is resolved into components parallel and perpendicular to this basis vector. The lengths of the two components are returned, together with the position of closest aproach of the basis vector to point 3.
- Parameters
-
[in] point1 The start of the basis vector, and of the vector to be resolved. [in] point2 The end of the basis vector. [in] point3 The end of the vector to be resolved.
- Returns
- a ResolvedPoint containing:
- point The point of closest approach of the basis vector to point 3.
- d1 The distance from point 1 to the returned point (that is, the length of the component parallel to the basis vector). Positive values are in the same sense as movement from point 1 to point 2.
- d2 The distance from the returned point to point 3 (that is, the length of the component perpendicular to the basis vector). The value is always positive.
Notes
- Each vector used in this method is the path of shortest distance between two points, as defined by distance
- This method will return
nancoordinate values if any of the input coordinates are invalid, or if the required output values are undefined.
◆ same()
|
inlineinherited |
◆ set()
|
inlineprotectedinherited |
Assign a set of attribute values, over-riding any previous values.
The attributes and their new values are specified via a character string, which should contain a comma-separated list of the form: "attribute_1 = value_1, attribute_2 = value_2, ... " where "attribute_n" specifies an attribute name, and the value to the right of each " =" sign should be a suitable textual representation of the value to be assigned. This value will be interpreted according to the attribute's data type.
Notes
- Attribute names are not case sensitive and may be surrounded by white space
- Attribute names are not case sensitive and may be surrounded by white space.
- White space may also surround attribute values, where it will generally be ignored (except for string-valued attributes where it is significant and forms part of the value to be assigned).
- To include a literal comma or percent sign in the value assigned to an attribute, the whole attribute value should be enclosed in quotation markes.
- Exceptions
-
std::runtime_error if the attribute is read-only
◆ setActiveUnit()
|
inlineinherited |
◆ setAlignSystem()
|
inlineinherited |
Set AlignSystem: the coordinate system used by convert and findFrame to align Frames.
Definition at line 1203 of file Frame.h.
◆ setAlignTimeScale()
|
inline |
Set AlignTimeScale: time scale in which to align TimeFrames.
Definition at line 142 of file TimeFrame.h.
◆ setB()
|
inlineprotectedinherited |
Set the value of an attribute as a bool.
If possible, the type you provide is converted to the actual type of the attribute.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ setBottom()
|
inlineinherited |
Set Bottom: the lowest axis value to display.
Definition at line 1208 of file Frame.h.
◆ setC()
|
inlineprotectedinherited |
Set the value of an attribute as a string.
If possible, the type you provide is converted to the actual type of the attribute.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ setD()
|
inlineprotectedinherited |
Set the value of an attribute as a double.
If possible, the type you provide is converted to the actual type of the attribute.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ setDigits() [1/2]
|
inlineinherited |
◆ setDigits() [2/2]
|
inlineinherited |
Set Digits for all axes: number of digits of precision.
Definition at line 1213 of file Frame.h.
◆ setDirection()
|
inlineinherited |
Set Direction for one axis: display axis in conventional direction?
Definition at line 1223 of file Frame.h.
◆ setDomain()
|
inlinevirtualinherited |
Set Domain: coordinate system domain.
Reimplemented in ast::FrameDict.
Definition at line 1230 of file Frame.h.
◆ setDut1()
|
inlineinherited |
◆ setEpoch() [1/2]
|
inlineinherited |
◆ setEpoch() [2/2]
|
inlineinherited |
◆ setF()
|
inlineprotectedinherited |
Set the value of an attribute as a float.
If possible, the type you provide is converted to the actual type of the attribute.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ setFormat()
|
inlineinherited |
Set Format for one axis: format specification for axis values.
Definition at line 1250 of file Frame.h.
◆ setI()
|
inlineprotectedinherited |
Set the value of an attribute as an int.
If possible, the type you provide is converted to the actual type of the attribute.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ setID()
|
inlineinherited |
◆ setIdent()
|
inlineinherited |
◆ setL()
|
inlineprotectedinherited |
Set the value of an attribute as a long int.
If possible, the type you provide is converted to the actual type of the attribute.
- Exceptions
-
std::runtime_error if the attribute does not exist or the value cannot be converted
◆ setLabel()
|
inlineinherited |
◆ setLTOffset()
|
inline |
Set LTOffset: the offset of Local Time from UTC, in hours.
Definition at line 145 of file TimeFrame.h.
◆ setMatchEnd()
|
inlineinherited |
◆ setMaxAxes()
|
inlineinherited |
◆ setMinAxes()
|
inlineinherited |
◆ setObsAlt()
|
inlineinherited |
◆ setObsLat()
|
inlineinherited |
◆ setObsLon()
|
inlineinherited |
◆ setPermute()
|
inlineinherited |
◆ setPreserveAxes()
|
inlineinherited |
◆ setReport()
|
inlineinherited |
◆ setSymbol()
|
inlineinherited |
Set Symbol(axis) for one axis: axis symbol.
◆ setSystem()
|
inlineinherited |
◆ setTimeOrigin()
|
inline |
Set TimeOrigin: the zero point for TimeFrame axis values.
Definition at line 148 of file TimeFrame.h.
◆ setTimeScale()
|
inline |
◆ setTitle()
|
inlineinherited |
◆ setTop()
|
inlineinherited |
◆ setUnit()
|
inlineinherited |
Set Unit(axis) for one axis: physical units for formatted axis values.
Definition at line 1336 of file Frame.h.
◆ setUseDefs()
|
inlineinherited |
◆ show() [1/2]
|
inherited |
◆ show() [2/2]
|
inherited |
Print a textual description the object to an ostream.
- Parameters
-
[in,out] os The stream to which to write the string representation. [in] showComments Show comments?
◆ simplified()
|
inlineinherited |
Return a simplied version of the mapping (which may be a compound Mapping such as a CmpMap).
Simplification eliminates redundant computational steps and merges separate steps which can be performed more efficiently in a single operation. As a simple example, a Mapping which multiplied coordinates by 5, and then multiplied the result by 10, could be simplified to a single step which multiplied by 50. Similarly, a Mapping which multiplied by 5, and then divided by 5, could be reduced to a simple copying operation.
This function should typically be applied to Mappings which have undergone substantial processing or have been formed by merging other Mappings. It is of potential benefit, for example, in reducing execution time if applied before using a Mapping to transform a large number of coordinates.
- Note
- If the supplied Mapping is a FrameSet, the returned Mapping will be a deep copy of the supplied FrameSet in which all the inter-Frame Mappings have been simplified. Mappings that have a set value for their ref Object_Ident "Ident" attribute are unchanged by simplification. This is so that their individual identity is preserved. This restriction does not apply to the simplification of Frames. The returned mapping is always independent of the original (a deep copy), unlike astSimplify.
◆ test()
|
inlineinherited |
Has this attribute been explicitly set (and not subsequently cleared)?
- Warning
- Unlike the underlying astTest function, throws an exception if an error results
Notes
- Attribute names are not case sensitive and may be surrounded by white space.
- As you might expect, the returned value for a read-only attribute is always
false.
- Exceptions
-
std::runtime_error if an error results.
◆ then()
Return a series compound mapping this(first(input)) containing shallow copies of the original.
- Parameters
-
[in] next the mapping whose input is the output of this mapping
- Exceptions
-
std::invalid_argument if the number of input axes of nextdoes not match the number of output axes of this mapping.
- Warning
- The contained mappings are shallow copies (just like AST); if you want deep copies then make them manually.
Definition at line 37 of file Mapping.cc.
◆ tranGridForward() [1/2]
|
inlineinherited |
Transform a grid of points in the forward direction.
- Parameters
-
[in] lbnd The coordinates of the centre of the first pixel in the input grid along each dimension, size = nIn [in] ubnd The coordinates of the centre of the last pixel in the input grid along each dimension, size = nIn [in] tol The maximum tolerable geometrical distortion which may be introduced as a result of approximating non-linear Mappings by a set of piece-wise linear transformations. This should be expressed as a displacement within the output coordinate system of the Mapping.
If piece-wise linear approximation is not required, a value of zero may be given. This will ensure that the Mapping is used without any approximation, but may increase execution time.
If the value is too high, discontinuities between the linear approximations used in adjacent panel will be higher. If this is a problem, reduce the tolerance value used.
- Parameters
-
[in] maxpix A value which specifies an initial scale size (in input grid points) for the adaptive algorithm which approximates non-linear Mappings with piece-wise linear transformations. Normally, this should be a large value (larger than any dimension of the region of the input grid being used). In this case, a first attempt to approximate the Mapping by a linear transformation will be made over the entire input region. If a smaller value is used, the input region will first be divided into sub-regions whose size does not exceed " maxpix" grid points in any dimension. Only at this point will attempts at approximation commence. This value may occasionally be useful in preventing false convergence of the adaptive algorithm in cases where the Mapping appears approximately linear on large scales, but has irregularities (e.g. holes) on smaller scales. A value of, say, 50 to 100 grid points can also be employed as a safeguard in general-purpose software, since the effect on performance is minimal. If too small a value is given, it will have the effect of inhibiting linear approximation altogether (equivalent to setting " tol" to zero). Although this may degrade performance, accurate results will still be obtained. [in] to Computed points, with dimensions (nPts, nOut), where nPts the desired number of points
◆ tranGridForward() [2/2]
|
inlineinherited |
Transform a grid of points in the inverse direction, returning the results as a new Array2D.
See the overload of tranGridForward that outputs the data as the last argument for more information
◆ tranGridInverse() [1/2]
◆ tranGridInverse() [2/2]
◆ under() [1/2]
Combine this frame with another to form a compound frame (CmpFrame), with the axes of this frame followed by the axes of the next frame.
A compound frame allows two component Frames (of any class) to be merged together to form a more complex Frame. The axes of the two component Frames then appear together in the resulting CmpFrame (those of this Frame, followed by those of next).
Since a CmpFrame is itself a Frame, it can be used as a component in forming further CmpFrames. Frames of arbitrary complexity may be built from simple individual Frames in this way.
Also since a Frame is a Mapping, a CmpFrame can also be used as a Mapping. Normally, a CmpFrame is simply equivalent to a UnitMap, but if either of the component Frames within a CmpFrame is a Region (a sub-class of Frame), then the CmpFrame will use the Region as a Mapping when transforming values for axes described by the Region. Thus input axis values corresponding to positions which are outside the Region will result in bad output axis values.
The name comes the way vectors are sometimes shown for matrix multiplication: vertically, with the first axis at the bottom and the last axis at the top.
- Parameters
-
[in] next The next frame in the compound frame (the final next.getNAxes() axes)
- Returns
- a new CmpFrame
- Warning
- The contained frames are shallow copies (just like AST); if you want deep copies then make them manually.
Definition at line 66 of file Frame.cc.
◆ under() [2/2]
|
inherited |
Return a parallel compound mapping containing shallow copies of the original.
The resulting mapping has getNIn() + next.getNIn() inputs and getNOut() + next.getNOut() outputs. The first getNIn() axes of input are transformed by this mapping, producing the first getNOut() axes of output. The remaining axes of input are processed by next, resulting in the remaining axes of output.
The name comes the way vectors are sometimes shown for matrix multiplication: vertically, with the first axis at the bottom and the last axis at the top.
- Parameters
-
[in] next the mapping that processes the final next.getNin()axes of input to produce the finalnext.getNout()axes of output.
- Warning
- The contained mappings are shallow copies (just like AST); if you want deep copies then make them manually.
Definition at line 39 of file Mapping.cc.
◆ unformat()
|
inlineinherited |
Read a formatted coordinate value (given as a character string) for a Frame axis and return the number of characters read and the value.
The principle use of this function is in decoding user-supplied input which contains formatted coordinate values. Free-format input is supported as far as possible. If input is ambiguous, it is interpreted with reference to the Frame's attributes (in particular, the Format string associated with the Frame's axis).
This function is, in essence, the inverse of astFormat.
Applicability:
Frame This function applies to all Frames. See the "Frame Input Format" section below for details of the input formats accepted by a basic Frame.
SkyFrame The SkyFrame class re-defines the input format to be suitable for representing angles and times, with the resulting coordinate value returned in radians. See the "SkyFrame Input Format" section below for details of the formats accepted.
FrameSet The input formats accepted by a FrameSet are determined by its current Frame (as specified by the Current attribute).
Frame Input Format:
The input format accepted for a basic Frame axis is as follows:
- An optional sign, followed by:
- A sequence of one or more digits possibly containing a decimal point, followed by:
- An optional exponent field.
- The exponent field, if present, consists of "E" or "e" followed by a possibly signed integer.
Examples of acceptable Frame input formats include:
991.25-1.61E8-.99e-17<bad>
SkyFrame Input Format:
The input format accepted for a SkyFrame axis is as follows:
- An optional sign, followed by between one and three fields representing either degrees, arc-minutes, arc-seconds or hours, minutes, seconds (e.g. "-12 42 03").
- Each field should consist of a sequence of one or more digits, which may include leading zeros. At most one field may contain a decimal point, in which case it is taken to be the final field (e.g. decimal degrees might be given as "124.707", while degrees and decimal arc-minutes might be given as "-13 33.8").
- The first field given may take any value, allowing angles and times outside the conventional ranges to be represented. However, subsequent fields must have values of less than 60 (e.g. "720 45 31" is valid, whereas "11 45 61" is not).
- Fields may be separated by white space or by ":" (colon), but the choice of separator must be used consistently throughout the value. Additional white space may be present around fields and separators (e.g. "- 2: 04 : 7.1").
- The following field identification characters may be used as separators to replace either of those above (or may be appended to the final field), in order to identify the field to which they are appended: "d"—degrees; "h"—hours; "m"—minutes of arc or time; "s"—seconds of arc or time; "'" (single quote)—minutes of arc; """ (double quote)—seconds of arc. Either lower or upper case may be used. Fields must be given in order of decreasing significance (e.g. "-11D 3' 14.4"" or "22h14m11.2s").
- The presence of any of the field identification characters "d", "'" (single quote) or """ (double quote) indicates that the value is to be interpreted as an angle. Conversely, the presence of "h" indicates that it is to be interpreted as a time (with 24 hours corresponding to 360 degrees). Incompatible angle/time identification characters may not be mixed (e.g. "10h14'3"" is not valid). The remaining field identification characters and separators do not specify a preference for an angle or a time and may be used with either.
- If no preference for an angle or a time is expressed anywhere within the value, it is interpreted as an angle if the Format attribute string associated with the SkyFrame axis generates an angle and as a time otherwise. This ensures that values produced by astFormat are correctly interpreted by Frame.unformat.
- If no preference for an angle or a time is expressed anywhere within the value, it is interpreted as an angle if the Format attribute string associated with the SkyFrame axis generates an angle and as a time otherwise. This ensures that values produced by Frame.format are correctly interpreted by Frame.unformat.
- Fields may be omitted, in which case they default to zero. The remaining fields may be identified by using appropriate field identification characters (see above) and/or by adding extra colon separators (e.g. "-05m13s" is equivalent to "-:05:13"). If a field is not identified explicitly, it is assumed that adjacent fields have been given, after taking account of any extra separator characters (e.g. "14:25.4s" specifies minutes and seconds, while "14::25.4s" specifies degrees and seconds).
- If fields are omitted in such a way that the remaining ones cannot be identified uniquely (e.g. "01:02"), then the first field (either given explicitly or implied by an extra leading colon separator) is taken to be the most significant field that astFormat would produce when formatting a value (using the Format attribute associated with the SkyFrame axis). By default, this means that the first field will normally be interpreted as degrees or hours. However, if this does not result in consistent field identification, then the last field (either given explicitly or implied by an extra trailing colon separator) is taken to to be the least significant field that astFormat would produce.
- If fields are omitted in such a way that the remaining ones cannot be identified uniquely (e.g. "01:02"), then the first field (either given explicitly or implied by an extra leading colon separator) is taken to be the most significant field that Frame.format would produce when formatting a value (using the Format attribute associated with the SkyFrame axis). By default, this means that the first field will normally be interpreted as degrees or hours. However, if this does not result in consistent field identification, then the last field (either given explicitly or implied by an extra trailing colon separator) is taken to to be the least significant field that Frame.format would produce.
This final convention is intended to ensure that values formatted by Frame.format which contain less than three fields will be correctly interpreted if read back using Frame.unformat, even if they do not contain field identification characters.
Examples of acceptable SkyFrame input formats (with interpretation in parentheses) include:
- ‘-14d 13m 22.2s (-14d 13’ 22.2")` - `+ 12:34:56.7` (12d 34' 56.7" or 12h 34m 56.7s)
001 : 02 : 03.4(1d 02' 03.4" or 1h 02m 03.4s)22h 30(22h 30m 00s)136::10"</tt> (136d 00' 10" or 136h 00m 10s)`-14M 27S` (-0d 14' 27" or -0h 14m 27s) - <tt>-:14:</tt> (-0d 14' 00" or -0h 14m 00s)`-::4.1` (-0d 00' 04.1" or -0h 00m 04.1s) - <tt>.9"(0d 00' 00.9") - `d12m` (0d 12' 00")H 12:22.3s(0h 12m 22.3s)<bad>(AST__BAD)
Where alternative interpretations are shown, the choice of angle or time depends on the associated Format(axis) attribute.
- Parameters
-
[in] axis The number of the Frame axis for which the coordinate value is to be read (axis numbering starts at zero for the first axis). [in] str String containing the formatted coordinate value.
- Returns
- an NReadValue containing the number of characters read and the value; if nread is 0 then the value is certainly invalid.
Notes
- Any white space at the beginning of the string will be skipped, as also will any trailing white space following the coordinate value read. The number of characters read will reflect this.
- The number of characters will be 0 and the value undefined if the string supplied does not contain a suitably formatted value.
- The string "<bad>" is recognised as a special case and will generate the value AST__BAD, without error. The test for this string is case-insensitive and permits embedded white space.
Definition at line 1502 of file Frame.h.
◆ unlock()
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inlineinherited |
Unlock this object previously locked using lock, so that other threads can use this object.
See lock for further details.
- Parameters
-
[in] report If true, an error will be reported if the supplied Object, or any Object contained within the supplied Object, is not currently locked by the running thread. If false, such Objects will be left unchanged, and no error will be reported.
Notes
- This function attempts to execute even if AST's global error status is set, but no further error report will be made if it subsequently fails under these circumstances.
- All unlocked Objects are excluded from AST context handling until they are re-locked using astLock.
- This function returns without action if the Object is not currently locked by any thread. If it is locked by the running thread, it is unlocked. If it is locked by another thread, an error will be reported if "error" is non-zero.
- This function returns without action if the AST library has been built without POSIX thread support (i.e. the "-with-pthreads" option was not specified when running the "configure" script).
Friends And Related Function Documentation
◆ Object
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friend |
Definition at line 81 of file TimeFrame.h.
The documentation for this class was generated from the following file:
- /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/astshim/22.0.1-1-geca5380+7fa3b7d9b6/include/astshim/TimeFrame.h
