chart2/source/tools/LogarithmicRegressionCurveCalculator.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 <LogarithmicRegressionCurveCalculator.hxx>
  21 #include <RegressionCalculationHelper.hxx>
  22 #include <SpecialCharacters.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 LogarithmicRegressionCurveCalculator::LogarithmicRegressionCurveCalculator() :
  33         m_fSlope( 0.0 ),
  34         m_fIntercept( 0.0 )
  35 {
  36     ::rtl::math::setNan( & m_fSlope );
  37     ::rtl::math::setNan( & m_fIntercept );
  38 }
  39
  40 LogarithmicRegressionCurveCalculator::~LogarithmicRegressionCurveCalculator()
  41 {}
  42
  43 // ____ XRegressionCurve ____
  44 void SAL_CALL LogarithmicRegressionCurveCalculator::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::isValidAndXPositive()));
  52
  53     const size_t nMax = aValues.first.size();
  54     if( nMax <= 1 )  // at least 2 points
  55     {
  56         ::rtl::math::setNan( & m_fSlope );
  57         ::rtl::math::setNan( & m_fIntercept );
  58         ::rtl::math::setNan( & m_fCorrelationCoeffitient );
  59         return;
  60     }
  61
  62     double fAverageX = 0.0, fAverageY = 0.0;
  63     size_t i = 0;
  64     for( i = 0; i < nMax; ++i )
  65     {
  66         fAverageX += log( aValues.first[i] );
  67         fAverageY += aValues.second[i];
  68     }
  69
  70     const double fN = static_cast< double >( nMax );
  71     fAverageX /= fN;
  72     fAverageY /= fN;
  73
  74     double fQx = 0.0, fQy = 0.0, fQxy = 0.0;
  75     for( i = 0; i < nMax; ++i )
  76     {
  77         double fDeltaX = log( aValues.first[i] ) - fAverageX;
  78         double fDeltaY = aValues.second[i] - fAverageY;
  79
  80         fQx  += fDeltaX * fDeltaX;
  81         fQy  += fDeltaY * fDeltaY;
  82         fQxy += fDeltaX * fDeltaY;
  83     }
  84
  85     m_fSlope = fQxy / fQx;
  86     m_fIntercept = fAverageY - m_fSlope * fAverageX;
  87     m_fCorrelationCoeffitient = fQxy / sqrt( fQx * fQy );
  88 }
  89
  90 double SAL_CALL LogarithmicRegressionCurveCalculator::getCurveValue( double x )
  91 {
  92     double fResult;
  93     ::rtl::math::setNan( & fResult );
  94
  95     if( ! ( ::rtl::math::isNan( m_fSlope ) ||
  96             ::rtl::math::isNan( m_fIntercept )))
  97     {
  98         fResult = m_fSlope * log( x ) + m_fIntercept;
  99     }
 100
 101     return fResult;
 102 }
 103
 104 uno::Sequence< geometry::RealPoint2D > SAL_CALL LogarithmicRegressionCurveCalculator::getCurveValues(
 105     double min, double max, ::sal_Int32 nPointCount,
 106     const uno::Reference< chart2::XScaling >& xScalingX,
 107     const uno::Reference< chart2::XScaling >& xScalingY,
 108     sal_Bool bMaySkipPointsInCalculation )
 109 {
 110     if( bMaySkipPointsInCalculation &&
 111         isLogarithmicScaling( xScalingX ) &&
 112         isLinearScaling( xScalingY ))
 113     {
 114         // optimize result
 115         uno::Sequence< geometry::RealPoint2D > aResult( 2 );
 116         aResult[0].X = min;
 117         aResult[0].Y = getCurveValue( min );
 118         aResult[1].X = max;
 119         aResult[1].Y = getCurveValue( max );
 120
 121         return aResult;
 122     }
 123     return RegressionCurveCalculator::getCurveValues( min, max, nPointCount, xScalingX, xScalingY, bMaySkipPointsInCalculation );
 124 }
 125
 126 OUString LogarithmicRegressionCurveCalculator::ImplGetRepresentation(
 127     const uno::Reference< util::XNumberFormatter >& xNumFormatter,
 128     sal_Int32 nNumberFormatKey, sal_Int32* pFormulaMaxWidth /* = nullptr */ ) const
 129 {
 130     bool bHasSlope = !rtl::math::approxEqual( fabs( m_fSlope ), 1.0 );
 131     OUStringBuffer aBuf( mYName + " = " );
 132     sal_Int32 nLineLength = aBuf.getLength();
 133     sal_Int32 nValueLength=0;
 134     if ( pFormulaMaxWidth && *pFormulaMaxWidth > 0 ) // count nValueLength
 135     {
 136         sal_Int32 nCharMin = nLineLength + 6 + mXName.getLength();  // 6 = "ln(x)" + 2 extra characters
 137         if( m_fSlope < 0.0 )
 138             nCharMin += 2;  // "- "
 139         if( m_fSlope != 0.0 && m_fIntercept != 0.0 )
 140         {
 141             nCharMin += 3; // " + "
 142             if ( bHasSlope )
 143                 nValueLength = (*pFormulaMaxWidth - nCharMin) / 2;
 144         }
 145         if ( nValueLength == 0 ) // not yet calculated
 146             nValueLength = *pFormulaMaxWidth - nCharMin;
 147         if ( nValueLength <= 0 )
 148             nValueLength = 1;
 149     }
 150
 151     // temporary buffer
 152     OUStringBuffer aTmpBuf("");
 153     // if nValueLength not calculated then nullptr
 154     sal_Int32* pValueLength = nValueLength ? &nValueLength : nullptr;
 155     if( m_fSlope != 0.0 )  // add slope value
 156     {
 157         if( m_fSlope < 0.0 )
 158         {
 159             aTmpBuf.append( OUStringChar(aMinusSign) ).append( " " );
 160         }
 161         if( bHasSlope )
 162         {
 163             OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fSlope), pValueLength );
 164             if ( aValueString != "1" )  // aValueString may be rounded to 1 if nValueLength is small
 165             {
 166                 aTmpBuf.append( aValueString ).append( " " );
 167             }
 168         }
 169         aTmpBuf.append( "ln(" ).append( mXName ).append( ") " );
 170         addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
 171         aTmpBuf.truncate();
 172
 173         if( m_fIntercept > 0.0 )
 174             aTmpBuf.append( "+ " );
 175     }
 176              // add intercept value
 177     if( m_fIntercept < 0.0 )
 178         aTmpBuf.append( OUStringChar(aMinusSign) ).append( " " );
 179     OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fIntercept), pValueLength );
 180     if ( aValueString != "0" )  // aValueString may be rounded to 0 if nValueLength is small
 181     {
 182         aTmpBuf.append( aValueString );
 183         addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
 184     }
 185
 186     if ( aBuf.toString() == (mYName + " = ") )
 187         aBuf.append( "0" );
 188
 189     return aBuf.makeStringAndClear();
 190 }
 191
 192 } //  namespace chart
 193
 194 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */