ScalarQuantColumn.h

Go to the documentation of this file.
00001 //# ScalarQuantColumn.h: Access to a Scalar Quantum Column in a table.
00002 //# Copyright (C) 1997,1998,1999,2000,2001
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 MEASURES_SCALARQUANTCOLUMN_H
00029 #define MEASURES_SCALARQUANTCOLUMN_H
00030 
00031 //# Includes
00032 #include <casacore/casa/aips.h>
00033 #include <casacore/casa/Quanta/Quantum.h>
00034 
00035 namespace casacore { //# NAMESPACE CASACORE - BEGIN
00036 
00037 //# Forward Declarations
00038 class Table;
00039 template <class T> class ScalarColumn;
00040 class String;
00041 class Unit;
00042 
00043 
00044 // <summary>
00045 // Provides access to Scalar Quantum Columns in Tables.
00046 // </summary>
00047 
00048 // <use visibility=export>
00049 
00050 // <reviewed reviewer="Bob Garwood" date="1999/12/23" tests="tTableQuantum.cc">
00051 // </reviewed>
00052 
00053 // <prerequisite>
00054 //# Classes you should understand before using this one.
00055 //   <li> <linkto class=TableQuantumDesc>TableQuantumDesc</linkto>
00056 //   <li> <linkto class=Table>Table</linkto>
00057 //   <li> <linkto class=ScalarColumn>ScalarColumn</linkto>
00058 //   <li> <linkto class=Quantum>Quantum</linkto>
00059 // </prerequisite>
00060 
00061 // <synopsis>
00062 // The ScalarQuantColumn class provides read/write access to quanta
00063 // stored in a scalar Quantum Table column.  The Quantum column should
00064 // already exist in the table and would have been defined by means of a
00065 // <linkto class=TableQuantumDesc>TableQuantumDesc object</linkto>.
00066 // In addition,
00067 // for a ScalarQuantColumn object to be useful the column should
00068 // contain Quanta.
00069 //
00070 // A ScalarQuantColumn object is used much in the same way as a
00071 // <linkto class=ScalarColumn>ScalarColumn</linkto> object.
00072 //
00073 // <h3>Quantum Units</h3></A>
00074 // Quanta retrieved from the column will normally have the Unit that was
00075 // specified when the Quantum column was defined.
00076 // However, it is possible to override the default column Unit by
00077 // supplying a Unit in the ScalarQuantColumn constructor.
00078 // When constructed in this fashion the retrieved Quanta will by
00079 // default be retrieved in this unit, i.e. they will by default be
00080 // converted to this unit.
00081 // <br>
00082 // By giving a unit (as a Unit or Quantum object) to a get function,
00083 // the data can be retrieved in another unit than the default.
00084 // </synopsis>
00085 
00086 // <example>
00087 // <srcblock>
00088 //     Quantum<Double> q(5.3, "keV");
00089 //     // "QuantScalar" has previously been defined as a Quantum column
00090 //     // by means of a TableQuantumDesc. This example assumes the column
00091 //     // already contains quanta.
00092 //     ScalarQuantColumn<Double> qCol(qtab, "QuantScalar");
00093 //     // return and print quanta as stored in the column
00094 //     for (i = 0; i < qtab.nrow(); i++) {
00095 //         cout << qCol(i) << endl;
00096 //     }
00097 //     // The following retrieves and converts the quanta to GHz.  They
00098 //     // are then divided by the Quantum constant QC::h (Planck).
00099 //     for (i=0; i < qtab.nrow(); i++) {
00100 //         cout << (qCol(i, "GHz"))/(QC::h);
00101 //     }
00102 // </srcblock>
00103 // </example>
00104 
00105 // <motivation>
00106 // Add support for Quanta in the Tables system.
00107 // </motivation>
00108 
00109 // <thrown>
00110 //    <li>TableInvOper if the Table column is null.
00111 // </thrown>
00112 
00113 // <todo asof="$DATE:$">
00114 //# A List of bugs, limitations, extensions or planned refinements.
00115 // <li> Functions like getColumn
00116 // </todo>
00117 
00118 
00119 template<class T> class ScalarQuantColumn
00120 {
00121 public:
00122   // The default constructor creates a null object. It is useful for creating
00123   // arrays of ScalarQuantColumn objects. Attempting to use a null object
00124   // will produce a segmentation fault so care needs to be taken to
00125   // initialise the objects by using the attach() member before any attempt
00126   // is made to use the object.  The isNull() member can be used to test
00127   // if a ScalarQuantColumn object is null.
00128   ScalarQuantColumn();
00129 
00130   // Create the ScalarQuantColumn from the specified table and column name.
00131   // The default unit for data retrieved is the unit in which they were stored.
00132   ScalarQuantColumn (const Table& tab, const String& columnName);
00133 
00134   // Create the ScalarQuantColumn from the specified table and column name.
00135   // The default unit for data retrieved is the given unit (the data is
00136   // converted as needed).
00137   ScalarQuantColumn (const Table& tab, const String& columnName,
00138                      const Unit&);
00139 
00140   // Copy constructor (copy semantics).
00141   ScalarQuantColumn (const ScalarQuantColumn<T>& that);
00142 
00143   ~ScalarQuantColumn();
00144 
00145   // Change the reference to another column.
00146   void reference (const ScalarQuantColumn<T>& that);
00147 
00148   // Attach a column to the object. Optionally supply a default unit
00149   // which has the same meaning as the constructor unit argument.
00150   // <group name="attach">
00151   void attach (const Table& tab, const String& columnName);
00152   void attach (const Table& tab, const String& columnName, const Unit&);
00153   // </group>
00154 
00155   // Get the quantum stored in the specified row.
00156   // <group name="get">
00157   void get (uInt rownr, Quantum<T>& q) const;
00158   // Get the quantum in the specified row, converted to the given unit.
00159   void get (uInt rownr, Quantum<T>& q, const Unit&) const;
00160   // Get the quantum in the specified row, converted to the unit in other.
00161   void get (uInt rownr, Quantum<T>& q, const Quantum<T>& other) const;
00162   // </group>
00163 
00164   // Return the quantum stored in the specified row.
00165   // <group>
00166   Quantum<T> operator() (uInt rownr) const;
00167   // Return the quantum stored in the specified row, converted to the
00168   // given unit.
00169   Quantum<T> operator() (uInt rownr, const Unit&) const;
00170   // Return the quantum in the specified row, converted to the unit in
00171   // other.
00172   Quantum<T> operator() (uInt rownr, const Quantum<T>& other) const;
00173   // </group>
00174 
00175   // Put a quantum into the table.  If the column supports variable units
00176   // the q's unit is stored into the unit column defined in the
00177   // TableQuantumDesc object.  If units are fixed for the column, the
00178   // quantum is converted as needed.
00179   void put (uInt rownr, const Quantum<T>& q);
00180 
00181   // Test whether the Quantum column has variable units
00182   Bool isUnitVariable() const
00183     { return (itsUnitsCol != 0); }
00184 
00185   // Returns the column's value for Units as a string.
00186   // An empty string is returned if the column has variable units.
00187   const String& getUnits() const
00188     { return itsUnit.getName(); }
00189 
00190   // Test if the object is null.
00191   Bool isNull() const
00192     { return (itsDataCol == 0); }
00193 
00194   // Throw an exception if the object is null.
00195   void throwIfNull() const;
00196 
00197   // get the column as a Quantum<Vector<T> >. If <src>unit</src> is
00198   // not empty, the returned Quantum will have that unit. Else if
00199   // the units are variable, the values in the returned Vector
00200   // have been converted to the unit of the 0th row entry. Otherwise,
00201   // the units of the returned Quantum are the units specified in
00202   // the column descriptor.
00203   SHARED_PTR<Quantum<Vector<T> > > getColumn(const Unit& unit="") const;
00204 
00205 protected:
00206   //# Quantum column's units (if units not variable)
00207   Unit itsUnit;
00208 
00209   // Get access to itsUnitsCol.
00210   const ScalarColumn<String>* unitsCol() const
00211     { return itsUnitsCol; }
00212 
00213 private:
00214   //# The underlying data column stores the quantum column's data.
00215   ScalarColumn<T>* itsDataCol;
00216   //# Variable units column if applicable.
00217   ScalarColumn<String>* itsUnitsCol;
00218   //# Unit to retrieve the data in.
00219   Unit itsUnitOut;
00220   //# Convert unit when getting data?
00221   Bool itsConvOut;
00222 
00223 
00224   // Assignment makes no sense in a read only class.
00225   // Declaring this operator private makes it unusable.
00226   ScalarQuantColumn& operator= (const ScalarQuantColumn<T>& that);
00227 
00228   // Comparison is not defined, since its semantics are unclear.
00229   Bool operator== (const ScalarQuantColumn<T>& that);
00230 
00231   // Initialize the ScalarQuantColumn from the specified table and column.
00232   void init (const Table& tab, const String& columnName);
00233 
00234   // Deletes allocated memory etc. Called by destructor and any member
00235   // which needs to reallocate data.
00236   void cleanUp();
00237 
00238   // Get the data without possible conversion.
00239   void getData (uInt rownr, Quantum<T>& q) const;
00240 };
00241 
00242 } //# NAMESPACE CASACORE - END
00243 
00244 
00245 //# Make old name ROScalarMeasColumn still available.
00246 #define ROScalarQuantColumn ScalarQuantColumn
00247 
00248 
00249 #ifndef CASACORE_NO_AUTO_TEMPLATES
00250 #include <casacore/measures/TableMeasures/ScalarQuantColumn.tcc>
00251 #endif //# CASACORE_NO_AUTO_TEMPLATES
00252 #endif
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Defines

Generated on 31 Aug 2016 for casa by  doxygen 1.6.1