StatisticsUtilities.h

Go to the documentation of this file.

//# 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
//#                        520 Edgemont Road
//#                        Charlottesville, VA 22903-2475 USA
//#

#ifndef SCIMATH_STATISTICSUTILITIES_H
#define SCIMATH_STATISTICSUTILITIES_H

#include <casacore/casa/Exceptions/Error.h>
#include <casacore/scimath/StatsFramework/StatisticsTypes.h>
#include <casacore/scimath/StatsFramework/StatsHistogram.h>
#include <casacore/casa/Utilities/DataType.h>
#include <casacore/casa/aips.h>

#include <iostream>
#include <casacore/casa/iosfwd.h>

namespace casacore {

template <class T> class PtrHolder;

CASA_STATD class StatsDataProvider;

// Various statistics related methods for the statistics framework.

template <class AccumType> class StatisticsUtilities {
public:

    StatisticsUtilities() = delete;

        ~StatisticsUtilities() {}

        // <group>
        // accumulate values. It is the responsibility of the caller to keep track
        // of the accumulated values after each call. This class does not since it
        // has no state. The accumulation derivation for mean and variance can be
        // found at
        // www.itl.nist.gov/div898/software/dataplot/refman2/ch2/weighvar.pdf
        // nvariance is an accumulated value. It is related to the variance via
        // variance = nvariance/npts or nvariance/(npts-1) depending on your
        // preferred definition in the non-weighted case and
        // wvariance = wnvariance/sumofweights or wnvariance/(sumofweights-1)
        // in the weighted case Its basic definition is
        // nvariance = sum((x_i - mean)**2),
        // wnvariance = sum((weight_i*(x_i - mean)**2)
        // npts is a Double rather than an Int64 because of compilation issues when
        // T is a Complex
        inline static void accumulate (
                Double& npts, AccumType& sum, AccumType& mean, const AccumType& datum
        );

        // in order to optimize performance, no checking is done for the
        // weight == 0 case callers should ensure that the weigth is not zero before
        // calling this method, and shouldn't call this method if the weight is 0.
        // Expect a segfault because of division by zero if sumweights and weight
        // are both zero.
        inline static void waccumulate (
                Double& npts, AccumType& sumweights, AccumType& wsum, AccumType& wmean,
                const AccumType& datum, const AccumType& weight
        );

        inline static void accumulate (
                Double& npts, AccumType& sum, AccumType& mean, AccumType& nvariance,
                AccumType& sumsq, const AccumType& datum
        );

        // wsumsq is the weighted sum of squares, sum(w_i*x_i*x_i)
        inline static void waccumulate (
                Double& npts, AccumType& sumweights, AccumType& wsum, AccumType& wmean,
                AccumType& wnvariance, AccumType& wsumsq, const AccumType& datum,
                const AccumType& weight
        );
        // </group>

        // <group>
        // The assignment operator of class LocationType should use copy, not
        // reference, semantics.
        template <class LocationType> inline static void accumulate (
                Double& npts, AccumType& sum, AccumType& mean, AccumType& nvariance,
                AccumType& sumsq, AccumType& datamin, AccumType& datamax,
                LocationType& minpos, LocationType& maxpos, const AccumType& datum,
                const LocationType& location
        );

        template <class LocationType, class DataType>
        inline static void accumulate (
            Double& npts, AccumType& sum, AccumType& mean, AccumType& nvariance,
            AccumType& sumsq, DataType& datamin, DataType& datamax,
            LocationType& minpos, LocationType& maxpos, const DataType& datum,
            const LocationType& location
        );

        template <class LocationType>
        inline static void waccumulate (
                Double& npts, AccumType& sumofweights, AccumType& sum, AccumType& mean,
                AccumType& nvariance, AccumType& sumsq, AccumType& datamin,
                AccumType& datamax, LocationType& minpos, LocationType& maxpos,
                const AccumType& datum, const AccumType& weight,
                const LocationType& location
        );
        // </group>

        // <group>
        // return True if the max or min was updated, False otherwise.
        template <class LocationType>
        inline static Bool doMax(
                AccumType& datamax, LocationType& maxpos, Bool isFirst,
                const AccumType& datum, const LocationType& location
        );

        template <class LocationType>
        inline static Bool doMin(
                AccumType& datamin, LocationType& minpos, Bool isFirst,
                const AccumType& datum, const LocationType& location
        );
        // </group>

        // <group>
        // These versions are for symmetric accumulation about a specified center
        // point. The actual point is accumulated, as is a "virtual" point that is
        // symmetric about the specified center. Of course, the trivial relationship
        // that the mean is the specified center is used to simplify things
        inline static void accumulateSym (
                Double& npts, AccumType& nvariance, AccumType& sumsq,
                const AccumType& datum, const AccumType& center
        );

        // wsumsq is the weighted sum of squares, sum(w_i*x_i*x_i)
        inline static void waccumulateSym (
                Double& npts, AccumType& sumweights, AccumType& wnvariance,
                AccumType& wsumsq, const AccumType& datum, const AccumType& weight,
                const AccumType& center
        );

        // <src>maxpos</src> and <src>minpos</src> refer to actual, not
        // virtually created, data only.
        template <class LocationType> inline static void accumulateSym (
                Double& npts, AccumType& nvariance,  AccumType& sumsq,
                AccumType& datamin, AccumType& datamax, LocationType& minpos,
                LocationType& maxpos, const AccumType& datum,
                const LocationType& location, const AccumType& center
        );

        template <class LocationType> inline static void waccumulateSym (
                Double& npts, AccumType& sumofweights, AccumType& nvariance,
                AccumType& sumsq, AccumType& datamin, AccumType& datamax,
                LocationType& minpos, LocationType& maxpos, const AccumType& datum,
                const AccumType& weight, const LocationType& location,
                const AccumType& center
        );

    // convert in place by taking the absolute value of the difference of the
        // std::vector and the median
    inline static void convertToAbsDevMedArray(
        DataArray& myArray, AccumType median
    );
        // </group>

        inline static Bool includeDatum(
                const AccumType& datum, typename DataRanges::const_iterator beginRange,
                typename DataRanges::const_iterator endRange, Bool isInclude
        );


    // The array can be changed by partially sorting it up to the largest index.
        // Return a map of index to value in the sorted array.
    static std::map<uInt64, AccumType> indicesToValues(
        std::vector<AccumType>& myArray, const std::set<uInt64>& indices
    );

    static void mergeResults(
        std::vector<BinCountArray>& bins,
        std::vector<CountedPtr<AccumType> >& sameVal,
        std::vector<Bool>& allSame,
        const PtrHolder<std::vector<BinCountArray>>& tBins,
        const PtrHolder<std::vector<CountedPtr<AccumType>>>& tSameVal,
        const PtrHolder<std::vector<Bool>>& tAllSame, uInt nThreadsMax
    );

    // use two statistics sets to get the statistics set that would
    // result in combining the two data sets used to produce the
    // individual statistics sets. The quantile related stats are
    // not considered, since it is not in general possible to determine
    // the resultant quantiles from the information provided; only
    // the aggregate statistics make sense.
    static StatsData<AccumType> combine(
        const std::vector<StatsData<AccumType>>& stats
    );

    template <class DataIterator, class MaskIterator, class WeightsIterator>
    static uInt nThreadsMax(
        const StatsDataProvider<CASA_STATP> *const dataProvider
    );

    static uInt threadIdx();

private:

        const static AccumType TWO;

};

}

#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/scimath/StatsFramework/StatisticsUtilities.tcc>
#endif //# CASACORE_NO_AUTO_TEMPLATES

#endif