StatsHistogram.h

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// # Copyright (C) 2000,2001
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library is distributed in the hope that it will be useful, but WITHOUT
// # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
// #
 
#ifndef SCIMATH_STATSHISTOGRAM_H
#define SCIMATH_STATSHISTOGRAM_H
 
#include <casacore/casa/Utilities/DataType.h>
#include <casacore/casa/aips.h>
#include <casacore/casa/Exceptions/Error.h>
 
#include <iostream>
#include <casacore/casa/iosfwd.h>
 
#include <vector>
 
namespace casacore {
 
// Represents an unfilled histogram with equal width bins for binning used for
// quantile computations. It is necessary to store the min/max values of the bin
// limits, because machine precision issues when the bin width is sufficiently
// small can cause slightly different results for these when different methods
// are used to compute them, leading to accounting errors when the histogram is
// filled with data.
 
template <class AccumType>
class StatsHistogram {
 public:
  StatsHistogram() = delete;
 
  // Construct a histogram by specifying its minimum and maximum values and
  // the number of desired bins. No padding of the min/max values is done
  // internally, so the caller should do that prior to construction if
  // necessary.
  StatsHistogram(AccumType minLimit, AccumType maxLimit, uInt nBins);
 
  ~StatsHistogram();
 
  // get the binWidth.
  AccumType getBinWidth() const;
 
  // get the index of the bin containing the specified value
  uInt getIndex(AccumType value) const;
 
  // max limit values for all bins
  const std::vector<AccumType>& getMaxBinLimits() const;
 
  // max limit value of entire histogram (ie max limit value of last bin)
  AccumType getMaxHistLimit() const;
 
  // min limit value of entire histogram (ie min limit value of first bin)
  AccumType getMinHistLimit() const;
 
  // get the number of bins
  uInt getNBins() const;
 
 private:
  AccumType _binWidth{0}, _minHistLimit{0}, _maxHistLimit{0};
  uInt _nBins{0};
  // maximum values for all bins
  std::vector<AccumType> _maxBinLimits{};
 
  // This does the obvious conversions. The Complex and DComplex
  // specializations (implemented below after the close of the class
  // definition) are used solely to permit compilation. In general, those
  // versions should never actually be called
  inline static uInt _getUInt(const AccumType& v) { return (uInt)v; }
 
  void _minMaxIdxRange(Int& minIdx, Int& maxIdx, AccumType value, Bool higher) const;
};
 
// <group>
// The Complex and DComplex versions are used solely to permit compilation. In
// general, these versions should never actually be called
 
template <>
inline uInt StatsHistogram<casacore::Complex>::_getUInt(const casacore::Complex&) {
  ThrowCc(
      "Logic Error: This version for complex "
      "data types should never be called");
}
 
template <>
inline uInt StatsHistogram<casacore::DComplex>::_getUInt(const casacore::DComplex&) {
  ThrowCc(
      "Logic Error: This version for complex "
      "data types should never be called");
}
// </group>
 
// for use in debugging
template <class AccumType>
ostream& operator<<(ostream& os, const StatsHistogram<AccumType>& hist) {
  os << "min limit " << hist.getMinHistLimit() << " max limit " << hist.getMaxHistLimit()
     << "  bin width " << hist.getBinWidth() << " nbins " << hist.getNBins();
  return os;
}
 
}  // namespace casacore
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include "StatsHistogram.tcc"
#endif  // # CASACORE_NO_AUTO_TEMPLATES
 
#endif