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.
   4  *
   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
  30 namespace chart
  31 {
  32
  33 ExponentialRegressionCurveCalculator::ExponentialRegressionCurveCalculator() :
  34         m_fLogSlope( 0.0 ),
  35         m_fLogIntercept( 0.0 )
  36 {
  37     ::rtl::math::setNan( & m_fLogSlope );
  38     ::rtl::math::setNan( & m_fLogIntercept );
  39 }
  40
  41 ExponentialRegressionCurveCalculator::~ExponentialRegressionCurveCalculator()
  42 {}
  43
  44 // ____ XRegressionCurveCalculator ____
  45 void SAL_CALL ExponentialRegressionCurveCalculator::recalculateRegression(
  46     const uno::Sequence< double >& aXValues,
  47     const uno::Sequence< double >& aYValues )
  48     throw (uno::RuntimeException)
  49 {
  50     RegressionCalculationHelper::tDoubleVectorPair aValues(
  51         RegressionCalculationHelper::cleanup(
  52             aXValues, aYValues,
  53             RegressionCalculationHelper::isValidAndYPositive()));
  54
  55     const size_t nMax = aValues.first.size();
  56     if( nMax == 0 )
  57     {
  58         ::rtl::math::setNan( & m_fLogSlope );
  59         ::rtl::math::setNan( & m_fLogIntercept );
  60         ::rtl::math::setNan( & m_fCorrelationCoeffitient );// actual it is coefficient of determination
  61         return;
  62     }
  63
  64     double fAverageX = 0.0, fAverageY = 0.0;
  65     size_t i = 0;
  66     for( i = 0; i < nMax; ++i )
  67     {
  68         fAverageX += aValues.first[i];
  69         fAverageY += log( aValues.second[i] );
  70     }
  71
  72     const double fN = static_cast< double >( nMax );
  73     fAverageX /= fN;
  74     fAverageY /= fN;
  75
  76     double fQx = 0.0, fQy = 0.0, fQxy = 0.0;
  77     for( i = 0; i < nMax; ++i )
  78     {
  79         double fDeltaX = aValues.first[i] - fAverageX;
  80         double fDeltaY = log( aValues.second[i] ) - fAverageY;
  81
  82         fQx  += fDeltaX * fDeltaX;
  83         fQy  += fDeltaY * fDeltaY;
  84         fQxy += fDeltaX * fDeltaY;
  85     }
  86
  87     m_fLogSlope = fQxy / fQx;
  88     m_fLogIntercept = fAverageY - m_fLogSlope * fAverageX;
  89     m_fCorrelationCoeffitient = fQxy / sqrt( fQx * fQy );
  90
  91 }
  92
  93 double SAL_CALL ExponentialRegressionCurveCalculator::getCurveValue( double x )
  94     throw (lang::IllegalArgumentException,
  95            uno::RuntimeException)
  96 {
  97     double fResult;
  98     ::rtl::math::setNan( & fResult );
  99
 100     if( ! ( ::rtl::math::isNan( m_fLogSlope ) ||
 101             ::rtl::math::isNan( m_fLogIntercept )))
 102     {
 103         fResult = exp(m_fLogIntercept + x * m_fLogSlope);
 104     }
 105
 106     return fResult;
 107 }
 108
 109 uno::Sequence< geometry::RealPoint2D > SAL_CALL ExponentialRegressionCurveCalculator::getCurveValues(
 110     double min, double max, ::sal_Int32 nPointCount,
 111     const uno::Reference< chart2::XScaling >& xScalingX,
 112     const uno::Reference< chart2::XScaling >& xScalingY,
 113     ::sal_Bool bMaySkipPointsInCalculation )
 114     throw (lang::IllegalArgumentException,
 115            uno::RuntimeException)
 116 {
 117     if( bMaySkipPointsInCalculation &&
 118         isLinearScaling( xScalingX ) &&
 119         isLogarithmicScaling( xScalingY ))
 120     {
 121         // optimize result
 122         uno::Sequence< geometry::RealPoint2D > aResult( 2 );
 123         aResult[0].X = min;
 124         aResult[0].Y = this->getCurveValue( min );
 125         aResult[1].X = max;
 126         aResult[1].Y = this->getCurveValue( max );
 127
 128         return aResult;
 129     }
 130
 131     return RegressionCurveCalculator::getCurveValues( min, max, nPointCount, xScalingX, xScalingY, bMaySkipPointsInCalculation );
 132 }
 133
 134
 135 OUString ExponentialRegressionCurveCalculator::ImplGetRepresentation(
 136     const uno::Reference< util::XNumberFormatter >& xNumFormatter,
 137     ::sal_Int32 nNumberFormatKey ) const
 138 {
 139     double fIntercept = exp(m_fLogIntercept);
 140     double fSlope = exp(m_fLogSlope);
 141     bool bHasSlope = !rtl::math::approxEqual( fSlope, 1.0 );
 142     bool bHasIntercept = !rtl::math::approxEqual( fIntercept, 1.0 );
 143
 144     OUStringBuffer aBuf( "f(x) = ");
 145
 146     if ( fIntercept == 0.0)
 147     {
 148         // underflow, a true zero is impossible
 149         aBuf.append( "exp( ");
 150         aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogIntercept) );
 151         aBuf.append( (m_fLogSlope < 0.0) ? " - " : " + ");
 152         aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fLogSlope)) );
 153         aBuf.append( " x )");
 154     }
 155     else
 156     {
 157         if (bHasIntercept)
 158         {
 159             aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, fIntercept) );
 160             aBuf.append( " exp( ");
 161             aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogSlope) );
 162             aBuf.append( " x )");
 163         }
 164         else
 165         {
 166             // show logarithmic output, if intercept and slope both are near one
 167             // otherwise drop output of intercept, which is 1 here
 168             aBuf.append( " exp( ");
 169             if (!bHasSlope)
 170             {
 171                 aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogIntercept) );
 172                 aBuf.append( (m_fLogSlope < 0.0) ? " - " : " + ");
 173                 aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fLogSlope)) );
 174             }
 175             else
 176             {
 177                 aBuf.append( getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogSlope) );
 178             }
 179             aBuf.append( " x )");
 180         }
 181     }
 182
 183     return aBuf.makeStringAndClear();
 184 }
 185
 186 } //  namespace chart
 187
 188 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */