chart2/source/tools/PotentialRegressionCurveCalculator.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 <PotentialRegressionCurveCalculator.hxx>
  21 #include <RegressionCalculationHelper.hxx>
  22 #include <SpecialCharacters.hxx>
  23
  24 #include <limits>
  25 #include <rtl/math.hxx>
  26 #include <rtl/ustrbuf.hxx>
  27
  28 using namespace ::com::sun::star;
  29
  30 namespace chart
  31 {
  32
  33 PotentialRegressionCurveCalculator::PotentialRegressionCurveCalculator()
  34     : m_fSlope(std::numeric_limits<double>::quiet_NaN())
  35     , m_fIntercept(std::numeric_limits<double>::quiet_NaN())
  36     , m_fSign(1.0)
  37 {
  38 }
  39
  40 PotentialRegressionCurveCalculator::~PotentialRegressionCurveCalculator()
  41 {}
  42
  43 // ____ XRegressionCurveCalculator ____
  44 void SAL_CALL PotentialRegressionCurveCalculator::recalculateRegression(
  45     const uno::Sequence< double >& aXValues,
  46     const uno::Sequence< double >& aYValues )
  47 {
  48     RegressionCalculationHelper::tDoubleVectorPair aValues(
  49         RegressionCalculationHelper::cleanup(
  50             aXValues, aYValues,
  51             RegressionCalculationHelper::isValidAndBothPositive()));
  52     m_fSign = 1.0;
  53
  54     size_t nMax = aValues.first.size();
  55     if( nMax <= 1 )  // at least 2 points
  56     {
  57         aValues = RegressionCalculationHelper::cleanup(
  58                     aXValues, aYValues,
  59                     RegressionCalculationHelper::isValidAndXPositiveAndYNegative());
  60         nMax = aValues.first.size();
  61         if( nMax <= 1 )
  62         {
  63             m_fSlope = std::numeric_limits<double>::quiet_NaN();
  64             m_fIntercept = std::numeric_limits<double>::quiet_NaN();
  65             m_fCorrelationCoefficient = std::numeric_limits<double>::quiet_NaN();
  66             return;
  67         }
  68         m_fSign = -1.0;
  69     }
  70
  71     double fAverageX = 0.0, fAverageY = 0.0;
  72     size_t i = 0;
  73     for( i = 0; i < nMax; ++i )
  74     {
  75         fAverageX += log( aValues.first[i] );
  76         fAverageY += log( m_fSign * aValues.second[i] );
  77     }
  78
  79     const double fN = static_cast< double >( nMax );
  80     fAverageX /= fN;
  81     fAverageY /= fN;
  82
  83     double fQx = 0.0, fQy = 0.0, fQxy = 0.0;
  84     for( i = 0; i < nMax; ++i )
  85     {
  86         double fDeltaX = log( aValues.first[i] ) - fAverageX;
  87         double fDeltaY = log( m_fSign * aValues.second[i] ) - fAverageY;
  88
  89         fQx  += fDeltaX * fDeltaX;
  90         fQy  += fDeltaY * fDeltaY;
  91         fQxy += fDeltaX * fDeltaY;
  92     }
  93
  94     m_fSlope = fQxy / fQx;
  95     m_fIntercept = fAverageY - m_fSlope * fAverageX;
  96     m_fCorrelationCoefficient = fQxy / sqrt( fQx * fQy );
  97
  98     m_fIntercept = m_fSign * exp( m_fIntercept );
  99 }
 100
 101 double SAL_CALL PotentialRegressionCurveCalculator::getCurveValue( double x )
 102 {
 103     if( ! ( std::isnan( m_fSlope ) ||
 104             std::isnan( m_fIntercept )))
 105     {
 106         return m_fIntercept * pow( x, m_fSlope );
 107     }
 108
 109     return std::numeric_limits<double>::quiet_NaN();
 110 }
 111
 112 uno::Sequence< geometry::RealPoint2D > SAL_CALL PotentialRegressionCurveCalculator::getCurveValues(
 113     double min, double max, ::sal_Int32 nPointCount,
 114     const uno::Reference< chart2::XScaling >& xScalingX,
 115     const uno::Reference< chart2::XScaling >& xScalingY,
 116     sal_Bool bMaySkipPointsInCalculation )
 117 {
 118     if( bMaySkipPointsInCalculation &&
 119         isLogarithmicScaling( xScalingX ) &&
 120         isLogarithmicScaling( xScalingY ))
 121     {
 122         // optimize result
 123         uno::Sequence< geometry::RealPoint2D > aResult{ { min, getCurveValue( min ) },
 124                                                         { max, getCurveValue( max ) } };
 125
 126         return aResult;
 127     }
 128     return RegressionCurveCalculator::getCurveValues( min, max, nPointCount, xScalingX, xScalingY, bMaySkipPointsInCalculation );
 129 }
 130
 131 OUString PotentialRegressionCurveCalculator::ImplGetRepresentation(
 132     const uno::Reference< util::XNumberFormatter >& xNumFormatter,
 133     sal_Int32 nNumberFormatKey, sal_Int32* pFormulaMaxWidth /* = nullptr */ ) const
 134 {
 135     bool bHasIntercept = !rtl::math::approxEqual( fabs(m_fIntercept), 1.0 );
 136     OUStringBuffer aBuf( mYName + " = " );
 137     sal_Int32 nLineLength = aBuf.getLength();
 138     sal_Int32 nValueLength=0;
 139     if ( pFormulaMaxWidth && *pFormulaMaxWidth > 0 ) // count nValueLength
 140     {
 141         sal_Int32 nCharMin = nLineLength + mXName.getLength() + 3;  // 3 = "^" + 2 extra characters
 142         if ( m_fIntercept != 0.0 && m_fSlope != 0.0 )
 143         {
 144             if ( m_fIntercept < 0.0 )
 145                 nCharMin += 2;  // "- "
 146             if ( bHasIntercept )
 147                 nValueLength = (*pFormulaMaxWidth - nCharMin) / 2;
 148         }
 149         if ( nValueLength == 0 ) // not yet calculated
 150             nValueLength = *pFormulaMaxWidth - nCharMin;
 151         if ( nValueLength <= 0 )
 152             nValueLength = 1;
 153     }
 154
 155     if( m_fIntercept == 0.0 )
 156     {
 157         aBuf.append( '0' );
 158     }
 159     else
 160     {
 161         // temporary buffer
 162         OUStringBuffer aTmpBuf("");
 163         // if nValueLength not calculated then nullptr
 164         sal_Int32* pValueLength = nValueLength ? &nValueLength : nullptr;
 165         if ( m_fIntercept < 0.0 )    // add intercept value
 166              aTmpBuf.append( OUStringChar(aMinusSign) + " " );
 167         if( bHasIntercept )
 168         {
 169             OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fIntercept), pValueLength );
 170             if ( aValueString != "1" )  // aValueString may be rounded to 1 if nValueLength is small
 171             {
 172                 aTmpBuf.append( aValueString + " " );
 173             }
 174         }
 175         if( m_fSlope != 0.0 )  // add slope value
 176         {
 177             aTmpBuf.append( mXName + "^" +
 178                  getFormattedString( xNumFormatter, nNumberFormatKey, m_fSlope, pValueLength ));
 179         }
 180         addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
 181     }
 182
 183     return aBuf.makeStringAndClear();
 184 }
 185
 186 } //  namespace chart
 187
 188 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */