MaskedLattice.h

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00001 //# MaskedLattice.h: Abstract base class for array-like classes with masks
00002 //# Copyright (C) 1998,1999,2000
00003 //# Associated Universities, Inc. Washington DC, USA.
00004 //#
00005 //# This library is free software; you can redistribute it and/or modify it
00006 //# under the terms of the GNU Library General Public License as published by
00007 //# the Free Software Foundation; either version 2 of the License, or (at your
00008 //# option) any later version.
00009 //#
00010 //# This library is distributed in the hope that it will be useful, but WITHOUT
00011 //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
00012 //# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
00013 //# License for more details.
00014 //#
00015 //# You should have received a copy of the GNU Library General Public License
00016 //# along with this library; if not, write to the Free Software Foundation,
00017 //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
00018 //#
00019 //# Correspondence concerning AIPS++ should be addressed as follows:
00020 //#        Internet email: aips2-request@nrao.edu.
00021 //#        Postal address: AIPS++ Project Office
00022 //#                        National Radio Astronomy Observatory
00023 //#                        520 Edgemont Road
00024 //#                        Charlottesville, VA 22903-2475 USA
00025 //#
00026 //# $Id$
00027 
00028 #ifndef LATTICES_MASKEDLATTICE_H
00029 #define LATTICES_MASKEDLATTICE_H
00030 
00031 
00032 //# Includes
00033 #include <casacore/casa/aips.h>
00034 #include <casacore/lattices/Lattices/Lattice.h>
00035 
00036 namespace casacore { //# NAMESPACE CASACORE - BEGIN
00037 
00038 //# Forward Declarations
00039 class LatticeRegion;
00040 
00041 
00042 // <summary>
00043 // A templated, abstract base class for array-like objects with masks.
00044 // </summary>
00045 
00046 // <use visibility=export>
00047 
00048 // <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="dLattice.cc">
00049 // </reviewed>
00050 
00051 // <prerequisite>
00052 //   <li> <linkto class="IPosition"> IPosition </linkto>
00053 //   <li> Abstract Base class Inheritance - try "Advanced C++" by James
00054 //        O. Coplien, Ch. 5.
00055 // </prerequisite>
00056 
00057 // <etymology>
00058 // Lattice: "A regular, periodic configuration of points, particles, 
00059 // or objects, throughout an area of a space..." (American Heritage Directory)
00060 // This definition matches our own: an n-dimensional arrangement of items,
00061 // on regular orthogonal axes.
00062 // </etymology>
00063 
00064 // <synopsis>
00065 // This pure abstract base class defines the operations which may be performed
00066 // on any concrete class derived from it.  It has only a few non-pure virtual 
00067 // member functions.
00068 // The fundamental contribution of this class, therefore, is that it 
00069 // defines the operations derived classes must provide:
00070 // <ul>
00071 //    <li> how to extract a "slice" (or sub-array, or subsection) from
00072 //         a Lattice.
00073 //    <li> how to copy a slice in.
00074 //    <li> how to get and put a single element 
00075 //    <li> how to apply a function to all elements
00076 //    <li> various shape related functions.
00077 // </ul>
00078 // <note role=tip> Lattices are always zero origined. </note>
00079 // </synopsis> 
00080 
00081 // <example>
00082 // Because Lattice is an abstract base class, an actual instance of this
00083 // class cannot be constructed. However the interface it defines can be used
00084 // inside a function. This is always recommended as it allows Functions
00085 // which have Lattices as arguments to work for any derived class.
00086 //
00087 // I will give a few examples here and then refer the reader to the 
00088 // <linkto class="ArrayLattice">ArrayLattice</linkto> class (a memory resident
00089 // Lattice) and the <linkto class="PagedArray">PagedArray</linkto> class (a
00090 // disk based Lattice) which contain further examples with concrete
00091 // classes (rather than an abstract one). All the examples shown below are used
00092 // in the <src>dLattice.cc</src> demo program.
00093 //
00094 // <h4>Example 1:</h4>
00095 // This example calculates the mean of the Lattice. Because Lattices can be too
00096 // large to fit into physical memory it is not good enough to simply use
00097 // <src>getSlice</src> to read all the elements into an Array. Instead the
00098 // Lattice is accessed in chunks which can fit into memory (the size is
00099 // determined by the <src>maxPixels</src> and <src>niceCursorShape</src>
00100 // functions). The <src>LatticeIterator::cursor()</src> function then returns
00101 // each of these chunks as an Array and the standard Array based functions are
00102 // used to calculate the mean on each of these chunks. Functions like this one
00103 // are the recommended way to access Lattices as the 
00104 // <linkto class="LatticeIterator">LatticeIterator</linkto> will correctly
00105 // setup any required caches.
00106 //
00107 // <srcblock>
00108 // Complex latMean(const Lattice<Complex>& lat) {
00109 //   const uInt cursorSize = lat.advisedMaxPixels();
00110 //   const IPosition cursorShape = lat.niceCursorShape(cursorSize);
00111 //   const IPosition latticeShape = lat.shape();
00112 //   Complex currentSum = 0.0f;
00113 //   size_t nPixels = 0;
00114 //   RO_LatticeIterator<Complex> iter(lat, 
00115 //                                 LatticeStepper(latticeShape, cursorShape));
00116 //   for (iter.reset(); !iter.atEnd(); iter++){
00117 //     currentSum += sum(iter.cursor());
00118 //     nPixels += iter.cursor().nelements();
00119 //   }
00120 //   return currentSum/nPixels;
00121 // }
00122 // </srcblock>
00123 //
00124 // <h4>Example 2:</h4>
00125 // Sometimes it will be neccesary to access slices of a Lattice in a nearly
00126 // random way. Often this can be done using the subSection commands in the
00127 // <linkto class="LatticeStepper">LatticeStepper</linkto> class. But it is also
00128 // possible to use the getSlice and putSlice functions. The following example
00129 // does a two-dimensional Real to Complex Fourier transform. This example is
00130 // restricted to four-dimensional Arrays (unlike the previous example) and does
00131 // not set up any caches (caching is currently only used with PagedArrays).  So
00132 // only use getSlice and putSlice when things cannot be done using
00133 // LatticeIterators.
00134 //
00135 // <srcblock>
00136 // void FFT2DReal2Complex(Lattice<Complex>& result, 
00137 //                     const Lattice<Float>& input){
00138 //   AlwaysAssert(input.ndim() == 4, AipsError);
00139 //   const IPosition shape = input.shape();
00140 //   const uInt nx = shape(0);
00141 //   AlwaysAssert (nx > 1, AipsError);
00142 //   const uInt ny = shape(1);
00143 //   AlwaysAssert (ny > 1, AipsError);
00144 //   const uInt npol = shape(2);
00145 //   const uInt nchan = shape(3); 
00146 //   const IPosition resultShape = result.shape();
00147 //   AlwaysAssert(resultShape.nelements() == 4, AipsError);
00148 //   AlwaysAssert(resultShape(3) == nchan, AipsError);
00149 //   AlwaysAssert(resultShape(2) == npol, AipsError);
00150 //   AlwaysAssert(resultShape(1) == ny, AipsError);
00151 //   AlwaysAssert(resultShape(0) == nx/2 + 1, AipsError);
00152 //
00153 //   const IPosition inputSliceShape(4,nx,ny,1,1);
00154 //   const IPosition resultSliceShape(4,nx/2+1,ny,1,1);
00155 //   COWPtr<Array<Float> > 
00156 //     inputArrPtr(new Array<Float>(inputSliceShape.nonDegenerate()));
00157 //   Array<Complex> resultArray(resultSliceShape.nonDegenerate());
00158 //   FFTServer<Float, Complex> FFT2D(inputSliceShape.nonDegenerate());
00159 //  
00160 //   IPosition start(4,0);
00161 //   Bool isARef;
00162 //   for (uInt c = 0; c < nchan; c++){
00163 //     for (uInt p = 0; p < npol; p++){
00164 //       isARef = input.getSlice(inputArrPtr,
00165 //                               Slicer(start,inputSliceShape), True);
00166 //       FFT2D.fft(resultArray, *inputArrPtr);
00167 //       result.putSlice(resultArray, start);
00168 //       start(2) += 1;
00169 //     }
00170 //     start(2) = 0;
00171 //     start(3) += 1;
00172 //   }
00173 // }
00174 // </srcblock>
00175 //
00176 // <h4>Example 3:</h4>
00177 // Occasionally you may want to access a few elements of a Lattice without
00178 // all the difficulty involved in setting up Iterators or calling getSlice
00179 // and putSlice. This is demonstrated in the example below and uses the
00180 // parenthesis operator, along with the LatticeValueRef companion
00181 // class. Using these functions to access many elements of a Lattice is not
00182 // recommended as this is the slowest access method.
00183 //
00184 // In this example an ideal point spread function will be inserted into an
00185 // empty Lattice. As with the previous examples all the action occurs
00186 // inside a function because Lattice is an interface (abstract) class.
00187 //
00188 // <srcblock>
00189 // void makePsf(Lattice<Float>& psf) {
00190 //   const IPosition centrePos = psf.shape()/2;
00191 //   psf.set(0.0f);       // this sets all the elements to zero
00192 //                        // As it uses a LatticeIterator it is efficient
00193 //   psf(centrePos) = 1;  // This sets just the centre element to one
00194 //   AlwaysAssert(near(psf(centrePos), 1.0f, 1E-6), AipsError);
00195 //   AlwaysAssert(near(psf(centrePos*0), 0.0f, 1E-6), AipsError);
00196 // }
00197 // </srcblock>
00198 // </example>
00199 
00200 // <motivation>
00201 // Creating an abstract base class which provides a common interface between
00202 // memory and disk based arrays has a number of advantages.
00203 // <ul>
00204 // <li> It allows functions common to all arrays to be written independent
00205 // of the way the data is stored. This is illustrated in the three examples
00206 // above. 
00207 // <li> It reduces the learning curve for new users who only have to become
00208 // familiar with one interface (ie. Lattice) rather than distinct interfaces
00209 // for different array types. 
00210 // </ul>
00211 // </motivation>
00212 
00213 //# <todo asof="1996/07/01">
00214 //#  <li>
00215 //# </todo>
00216 
00217 template <class T> class MaskedLattice : public Lattice<T>
00218 {
00219   //# Make members of parent class known.
00220 public:
00221   using Lattice<T>::ndim;
00222   using Lattice<T>::shape;
00223 
00224 public: 
00225   // Default constructor.
00226   MaskedLattice()
00227     : itsDefRegPtr(0) {;}
00228 
00229   // Copy constructor.
00230   MaskedLattice (const MaskedLattice<T>&);
00231 
00232   // a virtual destructor is needed so that it will use the actual destructor
00233   // in the derived class
00234   virtual ~MaskedLattice();
00235 
00236   // Make a copy of the object (reference semantics).
00237   // <group>
00238   virtual MaskedLattice<T>* cloneML() const = 0;
00239   virtual Lattice<T>* clone() const;
00240   // </group>
00241 
00242   // Has the object really a mask?
00243   // The default implementation returns True if the MaskedLattice has
00244   // a region with a mask.
00245   virtual Bool isMasked() const;
00246 
00247   // Does the lattice have a pixelmask?
00248   // The default implementation returns False.
00249   virtual Bool hasPixelMask() const;
00250 
00251   // Get access to the pixelmask.
00252   // An exception is thrown if the lattice does not have a pixelmask.
00253   // <group>
00254   virtual const Lattice<Bool>& pixelMask() const;
00255   virtual Lattice<Bool>& pixelMask();
00256   // </group>
00257 
00258   // Get the region used.
00259   // This is in principle the region pointed to by <src>getRegionPtr</src>.
00260   // However, if that pointer is 0, it returns a LatticeRegion for the
00261   // full image.
00262   const LatticeRegion& region() const;
00263 
00264   // Get the mask or a slice from the mask.
00265   // This is the mask formed by combination of the possible pixelmask of the
00266   // lattice and the possible mask of the region taken from the lattice.
00267   // If there is no mask, it still works fine.
00268   // In that case it sizes the buffer correctly and sets it to True.
00269   // <group>   
00270   Bool getMask (COWPtr<Array<Bool> >& buffer,
00271                 Bool removeDegenerateAxes=False) const;
00272   Bool getMaskSlice (COWPtr<Array<Bool> >& buffer, const Slicer& section,
00273                      Bool removeDegenerateAxes=False) const;
00274   Bool getMaskSlice (COWPtr<Array<Bool> >& buffer, const IPosition& start, 
00275                      const IPosition& shape,
00276                      Bool removeDegenerateAxes=False) const;
00277   Bool getMaskSlice (COWPtr<Array<Bool> >& buffer, const IPosition& start, 
00278                      const IPosition& shape, const IPosition& stride,
00279                      Bool removeDegenerateAxes=False) const;
00280   Bool getMask (Array<Bool>& buffer,
00281                 Bool removeDegenerateAxes=False);
00282   Bool getMaskSlice (Array<Bool>& buffer, const Slicer& section,
00283                      Bool removeDegenerateAxes=False);
00284   Bool getMaskSlice (Array<Bool>& buffer, const IPosition& start,
00285                      const IPosition& shape,
00286                      Bool removeDegenerateAxes=False);
00287   Bool getMaskSlice (Array<Bool>& buffer, const IPosition& start,
00288                      const IPosition& shape, const IPosition& stride,
00289                      Bool removeDegenerateAxes=False);
00290   Array<Bool> getMask (Bool removeDegenerateAxes=False) const;
00291   Array<Bool> getMaskSlice (const Slicer& section,
00292                             Bool removeDegenerateAxes=False) const;
00293   Array<Bool> getMaskSlice (const IPosition& start,
00294                             const IPosition& shape,
00295                             Bool removeDegenerateAxes=False) const;
00296   Array<Bool> getMaskSlice (const IPosition& start,
00297                             const IPosition& shape, const IPosition& stride,
00298                             Bool removeDegenerateAxes=False) const;
00299   // </group>
00300   
00301   // The function (in the derived classes) doing the actual work.
00302   // These functions are public, so they can be used internally in the
00303   // various Lattice classes.
00304   // <br>However, doGetMaskSlice does not call Slicer::inferShapeFromSource
00305   // to fill in possible unspecified section values. Therefore one
00306   // should normally use one of the getMask(Slice) functions. doGetMaskSlice
00307   // should be used with care and only when performance is an issue.
00308   // <br>The default implementation gets the mask from the region
00309   // and fills the buffer with True values if there is no region.
00310   virtual Bool doGetMaskSlice (Array<Bool>& buffer, const Slicer& section);
00311 
00312 protected:
00313   // Assignment can only be used by derived classes.
00314   MaskedLattice<T>& operator= (const MaskedLattice<T>&);
00315 
00316   // Get a pointer to the region used.
00317   // It can return 0 meaning that the MaskedLattice is the full lattice.
00318   virtual const LatticeRegion* getRegionPtr() const = 0;
00319 
00320 private:
00321   mutable LatticeRegion* itsDefRegPtr;
00322 };
00323 
00324 
00325 
00326 } //# NAMESPACE CASACORE - END
00327 
00328 #ifndef CASACORE_NO_AUTO_TEMPLATES
00329 #include <casacore/lattices/Lattices/MaskedLattice.tcc>
00330 #endif //# CASACORE_NO_AUTO_TEMPLATES
00331 #endif
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