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5c42c7636b
in property assistant Makes it easier to set suitable curves. Populated in the background for a nice reponsive widget!
122 lines
3.1 KiB
C++
122 lines
3.1 KiB
C++
/***************************************************************************
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qgshistogram.cpp
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----------------
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begin : May 2015
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copyright : (C) 2015 by Nyall Dawson
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email : nyall dot dawson at gmail dot com
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#include "qgshistogram.h"
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#include "qgsstatisticalsummary.h"
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#include "qgsvectorlayer.h"
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#include <qmath.h>
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QgsHistogram::QgsHistogram()
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: mMax( 0 )
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, mMin( 0 )
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, mIQR( 0 )
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{
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}
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void QgsHistogram::prepareValues()
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{
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std::sort( mValues.begin(), mValues.end() );
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QgsStatisticalSummary s;
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s.setStatistics( QgsStatisticalSummary::Max | QgsStatisticalSummary::Min | QgsStatisticalSummary::InterQuartileRange );
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s.calculate( mValues );
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mMin = s.min();
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mMax = s.max();
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mIQR = s.interQuartileRange();
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}
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void QgsHistogram::setValues( const QList<double> &values )
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{
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mValues = values;
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prepareValues();
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}
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bool QgsHistogram::setValues( const QgsVectorLayer *layer, const QString &fieldOrExpression, QgsFeedback* feedback )
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{
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mValues.clear();
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if ( !layer )
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return false;
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bool ok;
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mValues = layer->getDoubleValues( fieldOrExpression, ok, false, nullptr, feedback );
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if ( !ok )
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return false;
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prepareValues();
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return true;
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}
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double QgsHistogram::optimalBinWidth() const
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{
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//Freedman-Diaconis rule
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return 2.0 * mIQR * qPow( mValues.count(), -1 / 3.0 );
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}
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int QgsHistogram::optimalNumberBins() const
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{
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return ceil(( mMax - mMin ) / optimalBinWidth() );
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}
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QList<double> QgsHistogram::binEdges( int bins ) const
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{
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double binWidth = ( mMax - mMin ) / bins;
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QList<double> edges;
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edges.reserve( bins + 1 );
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edges << mMin;
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double current = mMin;
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for ( int i = 0; i < bins; ++i )
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{
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current += binWidth;
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edges << current;
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}
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return edges;
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}
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QList<int> QgsHistogram::counts( int bins ) const
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{
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QList<double> edges = binEdges( bins );
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QList<int> binCounts;
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binCounts.reserve( bins );
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int currentValueIndex = 0;
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for ( int i = 0; i < bins; ++i )
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{
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int count = 0;
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while ( currentValueIndex < mValues.count() && mValues.at( currentValueIndex ) < edges.at( i + 1 ) )
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{
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count++;
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currentValueIndex++;
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if ( currentValueIndex >= mValues.count() )
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break;
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}
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binCounts << count;
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}
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if ( currentValueIndex < mValues.count() )
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{
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//last value needs to be added
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binCounts[ bins - 1 ] = binCounts.last() + 1;
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}
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return binCounts;
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}
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