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 <sal/config.h>
  21
  22 #include <string_view>
  23
  24 #include <ExponentialRegressionCurveCalculator.hxx>
  25 #include <RegressionCalculationHelper.hxx>
  26 #include <SpecialCharacters.hxx>
  27
  28 #include <rtl/math.hxx>
  29 #include <rtl/ustrbuf.hxx>
  30
  31 using namespace ::com::sun::star;
  32
  33 namespace chart
  34 {
  35
  36 ExponentialRegressionCurveCalculator::ExponentialRegressionCurveCalculator()
  37     : m_fLogSlope(0.0)
  38     , m_fLogIntercept(0.0)
  39     , m_fSign(1.0)
  40 {
  41     ::rtl::math::setNan( & m_fLogSlope );
  42     ::rtl::math::setNan( & m_fLogIntercept );
  43 }
  44
  45 ExponentialRegressionCurveCalculator::~ExponentialRegressionCurveCalculator()
  46 {}
  47
  48 // ____ XRegressionCurveCalculator ____
  49 void SAL_CALL ExponentialRegressionCurveCalculator::recalculateRegression(
  50     const uno::Sequence< double >& aXValues,
  51     const uno::Sequence< double >& aYValues )
  52 {
  53     RegressionCalculationHelper::tDoubleVectorPair aValues(
  54         RegressionCalculationHelper::cleanup(
  55             aXValues, aYValues,
  56             RegressionCalculationHelper::isValidAndYPositive()));
  57     m_fSign = 1.0;
  58
  59     size_t nMax = aValues.first.size();
  60     if( nMax <= 1 ) // at least 2 points
  61     {
  62         aValues = RegressionCalculationHelper::cleanup(
  63                     aXValues, aYValues,
  64                     RegressionCalculationHelper::isValidAndYNegative());
  65         nMax = aValues.first.size();
  66         if( nMax <= 1 )
  67         {
  68             ::rtl::math::setNan( & m_fLogSlope );
  69             ::rtl::math::setNan( & m_fLogIntercept );
  70             ::rtl::math::setNan( & m_fCorrelationCoefficient );// actual it is coefficient of determination
  71             return;
  72         }
  73         m_fSign = -1.0;
  74     }
  75
  76     double fAverageX = 0.0, fAverageY = 0.0;
  77     double fLogIntercept = ( mForceIntercept && (m_fSign * mInterceptValue)>0 ) ? log(m_fSign * mInterceptValue) : 0.0;
  78     std::vector<double> yVector;
  79     yVector.resize(nMax, 0.0);
  80
  81     size_t i = 0;
  82     for( i = 0; i < nMax; ++i )
  83     {
  84         double yValue = log( m_fSign *aValues.second[i] );
  85         if (mForceIntercept)
  86         {
  87             yValue -= fLogIntercept;
  88         }
  89         else
  90         {
  91             fAverageX += aValues.first[i];
  92             fAverageY += yValue;
  93         }
  94         yVector[i] = yValue;
  95     }
  96
  97     const double fN = static_cast< double >( nMax );
  98     fAverageX /= fN;
  99     fAverageY /= fN;
 100
 101     double fQx = 0.0, fQy = 0.0, fQxy = 0.0;
 102     for( i = 0; i < nMax; ++i )
 103     {
 104         double fDeltaX = aValues.first[i] - fAverageX;
 105         double fDeltaY = yVector[i] - fAverageY;
 106
 107         fQx  += fDeltaX * fDeltaX;
 108         fQy  += fDeltaY * fDeltaY;
 109         fQxy += fDeltaX * fDeltaY;
 110     }
 111
 112     m_fLogSlope = fQxy / fQx;
 113     m_fLogIntercept = mForceIntercept ? fLogIntercept : fAverageY - m_fLogSlope * fAverageX;
 114     m_fCorrelationCoefficient = fQxy / sqrt( fQx * fQy );
 115 }
 116
 117 double SAL_CALL ExponentialRegressionCurveCalculator::getCurveValue( double x )
 118 {
 119     double fResult;
 120     ::rtl::math::setNan( & fResult );
 121
 122     if( ! ( std::isnan( m_fLogSlope ) ||
 123             std::isnan( m_fLogIntercept )))
 124     {
 125         fResult = m_fSign * exp(m_fLogIntercept + x * m_fLogSlope);
 126     }
 127
 128     return fResult;
 129 }
 130
 131 uno::Sequence< geometry::RealPoint2D > SAL_CALL ExponentialRegressionCurveCalculator::getCurveValues(
 132     double min, double max, ::sal_Int32 nPointCount,
 133     const uno::Reference< chart2::XScaling >& xScalingX,
 134     const uno::Reference< chart2::XScaling >& xScalingY,
 135     sal_Bool bMaySkipPointsInCalculation )
 136 {
 137     if( bMaySkipPointsInCalculation &&
 138         isLinearScaling( xScalingX ) &&
 139         isLogarithmicScaling( xScalingY ))
 140     {
 141         // optimize result
 142         uno::Sequence< geometry::RealPoint2D > aResult( 2 );
 143         aResult[0].X = min;
 144         aResult[0].Y = getCurveValue( min );
 145         aResult[1].X = max;
 146         aResult[1].Y = getCurveValue( max );
 147
 148         return aResult;
 149     }
 150
 151     return RegressionCurveCalculator::getCurveValues( min, max, nPointCount, xScalingX, xScalingY, bMaySkipPointsInCalculation );
 152 }
 153
 154 OUString ExponentialRegressionCurveCalculator::ImplGetRepresentation(
 155     const uno::Reference< util::XNumberFormatter >& xNumFormatter,
 156     sal_Int32 nNumberFormatKey, sal_Int32* pFormulaMaxWidth /* = nullptr */ ) const
 157 {
 158     double fIntercept = exp(m_fLogIntercept);
 159     bool bHasSlope = !rtl::math::approxEqual( exp(m_fLogSlope), 1.0 );
 160     bool bHasLogSlope = !rtl::math::approxEqual( fabs(m_fLogSlope), 1.0 );
 161     bool bHasIntercept = !rtl::math::approxEqual( fIntercept, 1.0 ) && fIntercept != 0.0;
 162
 163     OUStringBuffer aBuf( mYName + " = " );
 164     sal_Int32 nLineLength = aBuf.getLength();
 165     sal_Int32 nValueLength=0;
 166     if ( pFormulaMaxWidth && *pFormulaMaxWidth > 0 )
 167     {          // count characters different from coefficients
 168         sal_Int32 nCharMin = nLineLength + 10 + mXName.getLength();  // 10 = "exp( ", " x )" + 2 extra characters
 169         if ( m_fSign < 0.0 )
 170             nCharMin += 2;
 171         if ( fIntercept == 0.0 || ( !bHasSlope && m_fLogIntercept != 0.0 ) )
 172             nCharMin += 3; // " + " special case where equation is written exp( a + b x )
 173         if ( ( bHasIntercept || fIntercept == 0.0 || ( !bHasSlope && m_fLogIntercept != 0.0 ) ) &&
 174                bHasLogSlope )
 175             nValueLength = ( *pFormulaMaxWidth - nCharMin ) / 2;
 176         else
 177             nValueLength = *pFormulaMaxWidth - nCharMin;
 178         if ( nValueLength <= 0 )
 179             nValueLength = 1;
 180     }
 181                     // temporary buffer
 182     OUStringBuffer aTmpBuf("");
 183         // if nValueLength not calculated then nullptr
 184     sal_Int32* pValueLength = nValueLength ? &nValueLength : nullptr;
 185     if ( m_fSign < 0.0 )
 186         aTmpBuf.append( OUStringChar(aMinusSign) ).append( " " );
 187     if ( bHasIntercept )
 188     {
 189         OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fIntercept, pValueLength );
 190         if ( aValueString != "1" )  // aValueString may be rounded to 1 if nValueLength is small
 191         {
 192             aTmpBuf.append( aValueString ).append( " " );
 193             addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
 194             aTmpBuf.truncate();
 195         }
 196     }
 197     aTmpBuf.append( "exp( " );
 198     if ( !bHasIntercept )
 199     {
 200         if ( fIntercept == 0.0 ||  // underflow, a true zero is impossible
 201            ( !bHasSlope && m_fLogIntercept != 0.0 ) )   // show logarithmic output, if intercept and slope both are near one
 202         {                                               // otherwise drop output of intercept, which is 1 here
 203             OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, m_fLogIntercept, pValueLength );
 204             if ( aValueString != "0" )  // aValueString may be rounded to 0 if nValueLength is small
 205             {
 206                 aTmpBuf.append( aValueString ).append( (m_fLogSlope < 0.0) ? std::u16string_view(u" ") : std::u16string_view(u" + ") );
 207             }
 208         }
 209     }
 210     if ( m_fLogSlope < 0.0 )
 211         aTmpBuf.append( OUStringChar(aMinusSign) ).append( " " );
 212     if ( bHasLogSlope )
 213     {
 214         OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fLogSlope), pValueLength );
 215         if ( aValueString != "1" )  // aValueString may be rounded to 1 if nValueLength is small
 216         {
 217             aTmpBuf.append( aValueString ).append( " " );
 218         }
 219     }
 220     aTmpBuf.append( mXName ).append(" )");
 221     addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
 222
 223     return aBuf.makeStringAndClear();
 224 }
 225
 226 } //  namespace chart
 227
 228 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */