casacore
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casacore::LatticeExpr< T > Class Template Reference

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#include <LatticeExpr.h>

Public Member Functions

 LatticeExpr ()
 Default constructor. More...
 
 LatticeExpr (const LatticeExprNode &expr)
 Constructor from an arbitrary LatticeExprNode expression object. More...
 
 LatticeExpr (const LatticeExprNode &expr, const IPosition &latticeShape)
 
 LatticeExpr (const LatticeExpr< T > &other)
 Copy constructor (reference semantics) More...
 
virtual ~LatticeExpr ()
 Destructor, does nothing. More...
 
LatticeExpr< T > & operator= (const LatticeExpr< T > &other)
 Assignment (reference semantics) More...
 
virtual MaskedLattice< T > * cloneML () const
 Make a copy of the derived object (reference semantics). More...
 
virtual Bool isMasked () const
 Has the object really a mask? More...
 
virtual const LatticeRegiongetRegionPtr () const
 Get the region used (always returns 0). More...
 
virtual Bool isWritable () const
 Returns False, as the LatticeExpr lattice is not writable. More...
 
virtual Bool lock (FileLocker::LockType, uInt nattempts)
 Handle locking of the LatticeExpr which is delegated to all of its parts. More...
 
virtual void unlock ()
 
virtual Bool hasLock (FileLocker::LockType) const
 
virtual void resync ()
 Resynchronize the Lattice object with the lattice file. More...
 
virtual IPosition shape () const
 Returns the shape of the Lattice including all degenerate axes (i.e. More...
 
virtual IPosition doNiceCursorShape (uInt maxPixels) const
 Return the best cursor shape. More...
 
virtual LELCoordinates lelCoordinates () const
 Returns the coordinates of the lattice expression. More...
 
virtual Bool doGetSlice (Array< T > &buffer, const Slicer &section)
 Do the actual get of the data. More...
 
virtual Bool doGetMaskSlice (Array< Bool > &buffer, const Slicer &section)
 Do the actual get of the mask data. More...
 
virtual void doPutSlice (const Array< T > &sourceBuffer, const IPosition &where, const IPosition &stride)
 An expression is not writable so this functions throws an exception. More...
 
virtual void copyDataTo (Lattice< T > &to) const
 Copy the data from this lattice to the given lattice. More...
 
virtual void handleMathTo (Lattice< T > &to, int oper) const
 Handle the Math operators (+=, -=, *=, /=). More...
 
void handleMathTo (Lattice< Bool > &, int) const
 

Private Member Functions

void init (const LatticeExprNode &expr)
 Initialize the object from the expression. More...
 

Private Attributes

LatticeExprNode expr_p
 
IPosition shape_p
 
LELArray< T > * lastChunkPtr_p
 
Slicer lastSlicer_p
 

Detailed Description

template<class T>
class casacore::LatticeExpr< T >

Class to allow C++ expressions involving lattices

Intended use:

Public interface

Review Status

Date Reviewed:
yyyy/mm/dd

Prerequisite

Etymology

The name is derived from the fact that this class provides an expression interface to the user which s/he may use to write C++ expressions involving Lattices.

Synopsis

This class provides an interface which allows the C++ programmer to enter expressions such as "sin(a)+b" where "a" and "b" are Lattices.

This class is termed an envelope class, and inside it are the letter classes which do the real work. In reality, the letter classes are actually accessed via a bridging class called LatticeExprNode, which exists to handle type conversions. The letter classes iterate through the Lattices and evaluate the expression for each chunk of the iteration (usually a tile shape).

It is in the LatticeExprNode class that all the available expression operations are defined, so you should look there to see what functionality is available.

A description of the implementation details of these classes can be found in Note 216

Example

ArrayLattice<Float> f1(IPosition (2,nx,ny));
ArrayLattice<Float> f2(IPosition (2,nx,ny));
f2.set(2.0);
f1.copyData(2*f2+f2);

In this example, the values of the pixels in Lattice f1 are set to the values resulting from the expression "2*f2 + f2" I.e. the expression is evaluated for each pixel in the Lattices

Note that : 1) the Lattice::copyData function is expecting a Lattice argument.
2) LatticeExpr inherits from Lattice and therefore a LatticeExpr object is a valid argument object type 3) The expression in the copyData call is automatically converted to a LatticeExprNode by the constructors and operators in LatticeExprNode 4) The LatticeExprNode object so created is automatically converted to a LatticeExpr by casting functions in LatticeExprNode.

Example

ArrayLattice<Float> f1(IPosition (2,nx,ny));
ArrayLattice<Float> f2(IPosition (2,nx,ny));
ArrayLattice<Double> d(IPosition (2,nx,ny));
ArrayLattice<Complex> c(IPosition (2,nx,ny));
ArrayLattice<Bool> b(IPosition (2,nx,ny));
f2.set(1.0); d.set(2.0); c.set(Complex(2.0,3.0)); b.set(True);
f1.copyData((3.5*f2) + (cos(d)) - (10/min(d,f2)*(-abs(c))*ntrue(b)) - (C::pi));

In this rather silly example, we fill Lattice "f1" with the result of the expression. The expression shows the use of constants, unary operations, binary operations, 1D and 2D functions. It also shows how mixed types can be handled. The output Lattice is a Float, whereas mixed into the expression are subexpressions involving Float, Double, Complex and Bool Lattices.

Motivation

The Lattice expression classes enable the C++ programmer much simpler handling of mathematical expressions involving lattices. In addition, these classes provide the infrastructure on top of which we can build an image calculator for Glish users

To Do

Definition at line 142 of file LatticeExpr.h.

Constructor & Destructor Documentation

◆ LatticeExpr() [1/4]

template<class T >
casacore::LatticeExpr< T >::LatticeExpr ( )

Default constructor.

◆ LatticeExpr() [2/4]

template<class T >
casacore::LatticeExpr< T >::LatticeExpr ( const LatticeExprNode expr)

Constructor from an arbitrary LatticeExprNode expression object.

An exception is thrown if the expression data type cannot be converted to the template data type. The shape argument is mandatory if the expression has no shape. If the expression has a shape and if shape is given, it is checked if they are equal.

◆ LatticeExpr() [3/4]

template<class T >
casacore::LatticeExpr< T >::LatticeExpr ( const LatticeExprNode expr,
const IPosition latticeShape 
)

◆ LatticeExpr() [4/4]

template<class T >
casacore::LatticeExpr< T >::LatticeExpr ( const LatticeExpr< T > &  other)

Copy constructor (reference semantics)

◆ ~LatticeExpr()

template<class T >
virtual casacore::LatticeExpr< T >::~LatticeExpr ( )
virtual

Destructor, does nothing.

Member Function Documentation

◆ cloneML()

template<class T >
virtual MaskedLattice<T>* casacore::LatticeExpr< T >::cloneML ( ) const
virtual

Make a copy of the derived object (reference semantics).

◆ copyDataTo()

template<class T >
virtual void casacore::LatticeExpr< T >::copyDataTo ( Lattice< T > &  to) const
virtual

Copy the data from this lattice to the given lattice.

◆ doGetMaskSlice()

template<class T >
virtual Bool casacore::LatticeExpr< T >::doGetMaskSlice ( Array< Bool > &  buffer,
const Slicer section 
)
virtual

Do the actual get of the mask data.

The return value is always False, thus the buffer does not reference another array.

◆ doGetSlice()

template<class T >
virtual Bool casacore::LatticeExpr< T >::doGetSlice ( Array< T > &  buffer,
const Slicer section 
)
virtual

Do the actual get of the data.

The return value is always False, thus the buffer does not reference another array.

◆ doNiceCursorShape()

template<class T >
virtual IPosition casacore::LatticeExpr< T >::doNiceCursorShape ( uInt  maxPixels) const
virtual

Return the best cursor shape.


◆ doPutSlice()

template<class T >
virtual void casacore::LatticeExpr< T >::doPutSlice ( const Array< T > &  sourceBuffer,
const IPosition where,
const IPosition stride 
)
virtual

An expression is not writable so this functions throws an exception.

◆ getRegionPtr()

template<class T >
virtual const LatticeRegion* casacore::LatticeExpr< T >::getRegionPtr ( ) const
virtual

Get the region used (always returns 0).

◆ handleMathTo() [1/2]

void casacore::LatticeExpr< Bool >::handleMathTo ( Lattice< Bool > &  ,
int   
) const
inline

Definition at line 245 of file LatticeExpr.h.

◆ handleMathTo() [2/2]

template<class T >
virtual void casacore::LatticeExpr< T >::handleMathTo ( Lattice< T > &  to,
int  oper 
) const
virtual

Handle the Math operators (+=, -=, *=, /=).

They work similarly to copyData(To). However, they are not defined for Bool types, thus specialized below.

◆ hasLock()

template<class T >
virtual Bool casacore::LatticeExpr< T >::hasLock ( FileLocker::LockType  ) const
virtual

◆ init()

template<class T >
void casacore::LatticeExpr< T >::init ( const LatticeExprNode expr)
private

Initialize the object from the expression.

◆ isMasked()

template<class T >
virtual Bool casacore::LatticeExpr< T >::isMasked ( ) const
virtual

Has the object really a mask?

◆ isWritable()

template<class T >
virtual Bool casacore::LatticeExpr< T >::isWritable ( ) const
virtual

Returns False, as the LatticeExpr lattice is not writable.

◆ lelCoordinates()

template<class T >
virtual LELCoordinates casacore::LatticeExpr< T >::lelCoordinates ( ) const
virtual

Returns the coordinates of the lattice expression.

◆ lock()

template<class T >
virtual Bool casacore::LatticeExpr< T >::lock ( FileLocker::LockType  ,
uInt  nattempts 
)
virtual

Handle locking of the LatticeExpr which is delegated to all of its parts.


hasLock() is True if all parts of the expression return True.
It is strongly recommended to use class LatticeLocker to handle lattice locking. It also contains a more detailed explanation of the locking process.

◆ operator=()

template<class T >
LatticeExpr<T>& casacore::LatticeExpr< T >::operator= ( const LatticeExpr< T > &  other)

Assignment (reference semantics)

◆ resync()

template<class T >
virtual void casacore::LatticeExpr< T >::resync ( )
virtual

Resynchronize the Lattice object with the lattice file.

This function is only useful if no read-locking is used, ie. if the table lock option is UserNoReadLocking or AutoNoReadLocking. In that cases the table system does not acquire a read-lock, thus does not synchronize itself automatically.
By default the function does not do anything at all.

◆ shape()

template<class T >
virtual IPosition casacore::LatticeExpr< T >::shape ( ) const
virtual

Returns the shape of the Lattice including all degenerate axes (i.e.

axes with a length of one)

◆ unlock()

template<class T >
virtual void casacore::LatticeExpr< T >::unlock ( )
virtual

Member Data Documentation

◆ expr_p

template<class T >
LatticeExprNode casacore::LatticeExpr< T >::expr_p
private

Definition at line 237 of file LatticeExpr.h.

◆ lastChunkPtr_p

template<class T >
LELArray<T>* casacore::LatticeExpr< T >::lastChunkPtr_p
private

Definition at line 239 of file LatticeExpr.h.

◆ lastSlicer_p

template<class T >
Slicer casacore::LatticeExpr< T >::lastSlicer_p
private

Definition at line 240 of file LatticeExpr.h.

◆ shape_p

template<class T >
IPosition casacore::LatticeExpr< T >::shape_p
private

Definition at line 238 of file LatticeExpr.h.


The documentation for this class was generated from the following files:
casacore::abs
LatticeExprNode abs(const LatticeExprNode &expr)
Numerical 1-argument functions which result in a real number regardless of input expression type.
casacore::C::pi
const Double pi
Pi and functions thereof:
casacore::cos
LatticeExprNode cos(const LatticeExprNode &expr)
casacore::min
LatticeExprNode min(const LatticeExprNode &left, const LatticeExprNode &right)
casacore::ntrue
LatticeExprNode ntrue(const LatticeExprNode &expr)
casacore::C::c
const Double c
Fundamental physical constants (SI units):
casacore::True
const Bool True
Definition: aipstype.h:43
Complexfwd_global_functions_Complexfwd::casacore::Complex
std::complex< Float > Complex
Definition: Complexfwd.h:49