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