chart2/source/tools/ExponentialRegressionCurveCalculator.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
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   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #include "ExponentialRegressionCurveCalculator.hxx"
  21 #include "macros.hxx"
  22 #include "RegressionCalculationHelper.hxx"
  23
  24 #include <rtl/math.hxx>
  25 #include <rtl/ustrbuf.hxx>
  26
  27 using namespace ::com::sun::star;
  28
  29 namespace chart
  30 {
  31
  32 ExponentialRegressionCurveCalculator::ExponentialRegressionCurveCalculator() :
  33         m_fLogSlope( 0.0 ),
  34         m_fLogIntercept( 0.0 )
  35 {
  36     ::rtl::math::setNan( & m_fLogSlope );
  37     ::rtl::math::setNan( & m_fLogIntercept );
  38 }
  39
  40 ExponentialRegressionCurveCalculator::~ExponentialRegressionCurveCalculator()
  41 {}
  42
  43 // ____ XRegressionCurveCalculator ____
  44 void SAL_CALL ExponentialRegressionCurveCalculator::recalculateRegression(
  45     const uno::Sequence< double >& aXValues,
  46     const uno::Sequence< double >& aYValues )
  47     throw (uno::RuntimeException, std::exception)
  48 {
  49     RegressionCalculationHelper::tDoubleVectorPair aValues(
  50         RegressionCalculationHelper::cleanup(
  51             aXValues, aYValues,
  52             RegressionCalculationHelper::isValidAndYPositive()));
  53
  54     const size_t nMax = aValues.first.size();
  55     if( nMax == 0 )
  56     {
  57         ::rtl::math::setNan( & m_fLogSlope );
  58         ::rtl::math::setNan( & m_fLogIntercept );
  59         ::rtl::math::setNan( & m_fCorrelationCoeffitient );// actual it is coefficient of determination
  60         return;
  61     }
  62
  63     double fAverageX = 0.0, fAverageY = 0.0;
  64     double fLogIntercept = mForceIntercept ? log(mInterceptValue) : 0.0;
  65     std::vector<double> yVector;
  66     yVector.resize(nMax, 0.0);
  67
  68     size_t i = 0;
  69     for( i = 0; i < nMax; ++i )
  70     {
  71         double yValue = log(aValues.second[i]);
  72         if (mForceIntercept)
  73         {
  74             yValue -= fLogIntercept;
  75         }
  76         else
  77         {
  78             fAverageX += aValues.first[i];
  79             fAverageY += yValue;
  80         }
  81         yVector[i] = yValue;
  82     }
  83
  84     const double fN = static_cast< double >( nMax );
  85     fAverageX /= fN;
  86     fAverageY /= fN;
  87
  88     double fQx = 0.0, fQy = 0.0, fQxy = 0.0;
  89     for( i = 0; i < nMax; ++i )
  90     {
  91         double fDeltaX = aValues.first[i] - fAverageX;
  92         double fDeltaY = yVector[i] - fAverageY;
  93
  94         fQx  += fDeltaX * fDeltaX;
  95         fQy  += fDeltaY * fDeltaY;
  96         fQxy += fDeltaX * fDeltaY;
  97     }
  98
  99     m_fLogSlope = fQxy / fQx;
 100     m_fLogIntercept = mForceIntercept ? fLogIntercept : fAverageY - m_fLogSlope * fAverageX;
 101     m_fCorrelationCoeffitient = fQxy / sqrt( fQx * fQy );
 102 }
 103
 104 double SAL_CALL ExponentialRegressionCurveCalculator::getCurveValue( double x )
 105     throw (lang::IllegalArgumentException,
 106            uno::RuntimeException, std::exception)
 107 {
 108     double fResult;
 109     ::rtl::math::setNan( & fResult );
 110
 111     if( ! ( ::rtl::math::isNan( m_fLogSlope ) ||
 112             ::rtl::math::isNan( m_fLogIntercept )))
 113     {
 114         fResult = exp(m_fLogIntercept + x * m_fLogSlope);
 115     }
 116
 117     return fResult;
 118 }
 119
 120 uno::Sequence< geometry::RealPoint2D > SAL_CALL ExponentialRegressionCurveCalculator::getCurveValues(
 121     double min, double max, ::sal_Int32 nPointCount,
 122     const uno::Reference< chart2::XScaling >& xScalingX,
 123     const uno::Reference< chart2::XScaling >& xScalingY,
 124     sal_Bool bMaySkipPointsInCalculation )
 125     throw (lang::IllegalArgumentException,
 126            uno::RuntimeException, std::exception)
 127 {
 128     if( bMaySkipPointsInCalculation &&
 129         isLinearScaling( xScalingX ) &&
 130         isLogarithmicScaling( xScalingY ))
 131     {
 132         // optimize result
 133         uno::Sequence< geometry::RealPoint2D > aResult( 2 );
 134         aResult[0].X = min;
 135         aResult[0].Y = this->getCurveValue( min );
 136         aResult[1].X = max;
 137         aResult[1].Y = this->getCurveValue( max );
 138
 139         return aResult;
 140     }
 141
 142     return RegressionCurveCalculator::getCurveValues( min, max, nPointCount, xScalingX, xScalingY, bMaySkipPointsInCalculation );
 143 }
 144
 145 OUString ExponentialRegressionCurveCalculator::ImplGetRepresentation(
 146     const uno::Reference< util::XNumberFormatter >& xNumFormatter,
 147     ::sal_Int32 nNumberFormatKey ) const
 148 {
 149     double fIntercept = exp(m_fLogIntercept);
 150     double fSlope = exp(m_fLogSlope);
 151     bool bHasSlope = !rtl::math::approxEqual( fSlope, 1.0 );
 152     bool bHasIntercept = !rtl::math::approxEqual( fIntercept, 1.0 );
 153
 154     OUStringBuffer aBuf( "f(x) = ");
 155
 156     if ( fIntercept == 0.0)
 157     {
 158         // underflow, a true zero is impossible
 159         aBuf.append( "exp( ");
 160         aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogIntercept) );
 161         aBuf.append( (m_fLogSlope < 0.0) ? " - " : " + ");
 162         aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fLogSlope)) );
 163         aBuf.append( " x )");
 164     }
 165     else
 166     {
 167         if (bHasIntercept)
 168         {
 169             aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, fIntercept) );
 170             aBuf.append( " exp( ");
 171             aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogSlope) );
 172             aBuf.append( " x )");
 173         }
 174         else
 175         {
 176             // show logarithmic output, if intercept and slope both are near one
 177             // otherwise drop output of intercept, which is 1 here
 178             aBuf.append( " exp( ");
 179             if (!bHasSlope)
 180             {
 181                 aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogIntercept) );
 182                 aBuf.append( (m_fLogSlope < 0.0) ? " - " : " + ");
 183                 aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fLogSlope)) );
 184             }
 185             else
 186             {
 187                 aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogSlope) );
 188             }
 189             aBuf.append( " x )");
 190         }
 191     }
 192
 193     return aBuf.makeStringAndClear();
 194 }
 195
 196 } //  namespace chart
 197
 198 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */