Use doubles, not float values, within zonal stats

Author: nyalldawson

src/analysis/vector/qgszonalstatistics.cpp

@@ -328,12 +328,12 @@ int QgsZonalStatistics::calculateStatistics( QgsFeedback *feedback )
         std::sort( vals.begin(), vals.end() );
         if ( mStatistics & QgsZonalStatistics::Minority )
         {
-          float minorityKey = featureStats.valueCount.key( vals.first() );
+          double minorityKey = featureStats.valueCount.key( vals.first() );
           changeAttributeMap.insert( minorityIndex, QVariant( minorityKey ) );
         }
         if ( mStatistics & QgsZonalStatistics::Majority )
         {
-          float majKey = featureStats.valueCount.key( vals.last() );
+          double majKey = featureStats.valueCount.key( vals.last() );
           changeAttributeMap.insert( majorityIndex, QVariant( majKey ) );
         }
       }
@@ -422,15 +422,16 @@ void QgsZonalStatistics::statisticsFromMiddlePointTest( const QgsGeometry &poly,
     cellCenterX = rasterBBox.xMinimum() + pixelOffsetX * cellSizeX + cellSizeX / 2;
     for ( int j = 0; j < nCellsX; ++j )
     {
-      if ( validPixel( block->value( i, j ) ) )
+      double pixelValue = block->value( i, j );
+      if ( validPixel( pixelValue ) )
       {
         cellCenterCoords = GEOSCoordSeq_create_r( geosctxt, 1, 2 );
         GEOSCoordSeq_setX_r( geosctxt, cellCenterCoords, 0, cellCenterX );
         GEOSCoordSeq_setY_r( geosctxt, cellCenterCoords, 0, cellCenterY );
         currentCellCenter.reset( GEOSGeom_createPoint_r( geosctxt, cellCenterCoords ) );
         if ( GEOSPreparedContains_r( geosctxt, polyGeosPrepared.get(), currentCellCenter.get() ) )
         {
-          stats.addValue( block->value( i, j ) );
+          stats.addValue( pixelValue );
         }
       }
       cellCenterX += cellSizeX;
@@ -461,7 +462,8 @@ void QgsZonalStatistics::statisticsFromPreciseIntersection( const QgsGeometry &p
     double currentX = rasterBBox.xMinimum() + cellSizeX / 2.0 + pixelOffsetX * cellSizeX;
     for ( int j = 0; j < nCellsX; ++j )
     {
-      if ( !validPixel( block->value( i, j ) ) )
+      double pixelValue = block->value( i, j );
+      if ( !validPixel( pixelValue ) )
       {
         continue;
       }
@@ -477,7 +479,7 @@ void QgsZonalStatistics::statisticsFromPreciseIntersection( const QgsGeometry &p
           if ( intersectionArea >= 0.0 )
           {
             weight = intersectionArea / pixelArea;
-            stats.addValue( block->value( i, j ), weight );
+            stats.addValue( pixelValue, weight );
           }
         }
         pixelRectGeometry = QgsGeometry();

src/analysis/vector/qgszonalstatistics.h

@@ -84,10 +84,19 @@ class ANALYSIS_EXPORT QgsZonalStatistics
           : mStoreValues( storeValues )
           , mStoreValueCounts( storeValueCounts )
         {
-          reset();
         }
-        void reset() { sum = 0; count = 0; max = -FLT_MAX; min = FLT_MAX; valueCount.clear(); values.clear(); }
-        void addValue( float value, double weight = 1.0 )
+
+        void reset()
+        {
+          sum = 0;
+          count = 0;
+          max = std::numeric_limits<double>::lowest();
+          min = std::numeric_limits<double>::max();
+          valueCount.clear();
+          values.clear();
+        }
+
+        void addValue( double value, double weight = 1.0 )
         {
           if ( weight < 1.0 )
           {
@@ -106,16 +115,16 @@ class ANALYSIS_EXPORT QgsZonalStatistics
           if ( mStoreValues )
             values.append( value );
         }
-        double sum;
-        double count;
-        float max;
-        float min;
-        QMap< float, int > valueCount;
-        QList< float > values;
+        double sum = 0.0;
+        double count = 0.0;
+        double max = std::numeric_limits<double>::lowest();
+        double min = std::numeric_limits<double>::max();
+        QMap< double, int > valueCount;
+        QList< double > values;
 
       private:
-        bool mStoreValues;
-        bool mStoreValueCounts;
+        bool mStoreValues = false;
+        bool mStoreValueCounts = false;
     };
 
     /**