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: aips2-request@nrao.edu.
//#        Postal address: AIPS++ Project Office
//#                        National Radio Astronomy Observatory
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//#

#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;
}

}

#ifndef CASACORE_NO_AUTO_TEMPLATES
#include "StatsHistogram.tcc"
#endif //# CASACORE_NO_AUTO_TEMPLATES

#endif