Esempio n. 1
0
int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )
{
  if ( !mPolygonLayer || mPolygonLayer->geometryType() != QGis::Polygon )
  {
    return 1;
  }

  QgsVectorDataProvider* vectorProvider = mPolygonLayer->dataProvider();
  if ( !vectorProvider )
  {
    return 2;
  }

  //open the raster layer and the raster band
  GDALAllRegister();
  GDALDatasetH inputDataset = GDALOpen( mRasterFilePath.toLocal8Bit().data(), GA_ReadOnly );
  if ( inputDataset == NULL )
  {
    return 3;
  }

  if ( GDALGetRasterCount( inputDataset ) < ( mRasterBand - 1 ) )
  {
    GDALClose( inputDataset );
    return 4;
  }

  GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset, mRasterBand );
  if ( rasterBand == NULL )
  {
    GDALClose( inputDataset );
    return 5;
  }
  mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, NULL );

  //get geometry info about raster layer
  int nCellsX = GDALGetRasterXSize( inputDataset );
  int nCellsY = GDALGetRasterYSize( inputDataset );
  double geoTransform[6];
  if ( GDALGetGeoTransform( inputDataset, geoTransform ) != CE_None )
  {
    GDALClose( inputDataset );
    return 6;
  }
  double cellsizeX = geoTransform[1];
  if ( cellsizeX < 0 )
  {
    cellsizeX = -cellsizeX;
  }
  double cellsizeY = geoTransform[5];
  if ( cellsizeY < 0 )
  {
    cellsizeY = -cellsizeY;
  }
  QgsRectangle rasterBBox( geoTransform[0], geoTransform[3] - ( nCellsY * cellsizeY ), geoTransform[0] + ( nCellsX * cellsizeX ), geoTransform[3] );

  //add the new count, sum, mean fields to the provider
  QList<QgsField> newFieldList;
  QgsField countField( mAttributePrefix + "count", QVariant::Double );
  QgsField sumField( mAttributePrefix + "sum", QVariant::Double );
  QgsField meanField( mAttributePrefix + "mean", QVariant::Double );
  newFieldList.push_back( countField );
  newFieldList.push_back( sumField );
  newFieldList.push_back( meanField );
  if ( !vectorProvider->addAttributes( newFieldList ) )
  {
    return 7;
  }

  //index of the new fields
  int countIndex = vectorProvider->fieldNameIndex( mAttributePrefix + "count" );
  int sumIndex = vectorProvider->fieldNameIndex( mAttributePrefix + "sum" );
  int meanIndex = vectorProvider->fieldNameIndex( mAttributePrefix + "mean" );

  if ( countIndex == -1 || sumIndex == -1 || meanIndex == -1 )
  {
    return 8;
  }

  //progress dialog
  long featureCount = vectorProvider->featureCount();
  if ( p )
  {
    p->setMaximum( featureCount );
  }


  //iterate over each polygon
  vectorProvider->select( QgsAttributeList(), QgsRectangle(), true, false );
  vectorProvider->rewind();
  QgsFeature f;
  double count = 0;
  double sum = 0;
  double mean = 0;
  int featureCounter = 0;

  while ( vectorProvider->nextFeature( f ) )
  {
    qWarning( "%d", featureCounter );
    if ( p )
    {
      p->setValue( featureCounter );
    }

    if ( p && p->wasCanceled() )
    {
      break;
    }

    QgsGeometry* featureGeometry = f.geometry();
    if ( !featureGeometry )
    {
      ++featureCounter;
      continue;
    }

    int offsetX, offsetY, nCellsX, nCellsY;
    if ( cellInfoForBBox( rasterBBox, featureGeometry->boundingBox(), cellsizeX, cellsizeY, offsetX, offsetY, nCellsX, nCellsY ) != 0 )
    {
      ++featureCounter;
      continue;
    }

    statisticsFromMiddlePointTest_improved( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
                                            rasterBBox, sum, count );

    if ( count <= 1 )
    {
      //the cell resolution is probably larger than the polygon area. We switch to precise pixel - polygon intersection in this case
      statisticsFromPreciseIntersection( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
                                         rasterBBox, sum, count );
    }


    if ( count == 0 )
    {
      mean = 0;
    }
    else
    {
      mean = sum / count;
    }

    //write the statistics value to the vector data provider
    QgsChangedAttributesMap changeMap;
    QgsAttributeMap changeAttributeMap;
    changeAttributeMap.insert( countIndex, QVariant( count ) );
    changeAttributeMap.insert( sumIndex, QVariant( sum ) );
    changeAttributeMap.insert( meanIndex, QVariant( mean ) );
    changeMap.insert( f.id(), changeAttributeMap );
    vectorProvider->changeAttributeValues( changeMap );

    ++featureCounter;
  }

  if ( p )
  {
    p->setValue( featureCount );
  }

  GDALClose( inputDataset );
  return 0;
}
Esempio n. 2
0
int QgsZonalStatistics::calculateStatistics( QgsFeedback *feedback )
{
  if ( !mPolygonLayer || mPolygonLayer->geometryType() != QgsWkbTypes::PolygonGeometry )
  {
    return 1;
  }

  QgsVectorDataProvider *vectorProvider = mPolygonLayer->dataProvider();
  if ( !vectorProvider )
  {
    return 2;
  }

  if ( !mRasterLayer )
  {
    return 3;
  }

  if ( mRasterLayer->bandCount() < mRasterBand )
  {
    return 4;
  }

  mRasterProvider = mRasterLayer->dataProvider();
  mInputNodataValue = mRasterProvider->sourceNoDataValue( mRasterBand );

  //get geometry info about raster layer
  int nCellsXProvider = mRasterProvider->xSize();
  int nCellsYProvider = mRasterProvider->ySize();
  double cellsizeX = mRasterLayer->rasterUnitsPerPixelX();
  if ( cellsizeX < 0 )
  {
    cellsizeX = -cellsizeX;
  }
  double cellsizeY = mRasterLayer->rasterUnitsPerPixelY();
  if ( cellsizeY < 0 )
  {
    cellsizeY = -cellsizeY;
  }
  QgsRectangle rasterBBox = mRasterProvider->extent();

  //add the new fields to the provider
  QList<QgsField> newFieldList;
  QString countFieldName;
  if ( mStatistics & QgsZonalStatistics::Count )
  {
    countFieldName = getUniqueFieldName( mAttributePrefix + "count", newFieldList );
    QgsField countField( countFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( countField );
  }
  QString sumFieldName;
  if ( mStatistics & QgsZonalStatistics::Sum )
  {
    sumFieldName = getUniqueFieldName( mAttributePrefix + "sum", newFieldList );
    QgsField sumField( sumFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( sumField );
  }
  QString meanFieldName;
  if ( mStatistics & QgsZonalStatistics::Mean )
  {
    meanFieldName = getUniqueFieldName( mAttributePrefix + "mean", newFieldList );
    QgsField meanField( meanFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( meanField );
  }
  QString medianFieldName;
  if ( mStatistics & QgsZonalStatistics::Median )
  {
    medianFieldName = getUniqueFieldName( mAttributePrefix + "median", newFieldList );
    QgsField medianField( medianFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( medianField );
  }
  QString stdevFieldName;
  if ( mStatistics & QgsZonalStatistics::StDev )
  {
    stdevFieldName = getUniqueFieldName( mAttributePrefix + "stdev", newFieldList );
    QgsField stdField( stdevFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( stdField );
  }
  QString minFieldName;
  if ( mStatistics & QgsZonalStatistics::Min )
  {
    minFieldName = getUniqueFieldName( mAttributePrefix + "min", newFieldList );
    QgsField minField( minFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( minField );
  }
  QString maxFieldName;
  if ( mStatistics & QgsZonalStatistics::Max )
  {
    maxFieldName = getUniqueFieldName( mAttributePrefix + "max", newFieldList );
    QgsField maxField( maxFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( maxField );
  }
  QString rangeFieldName;
  if ( mStatistics & QgsZonalStatistics::Range )
  {
    rangeFieldName = getUniqueFieldName( mAttributePrefix + "range", newFieldList );
    QgsField rangeField( rangeFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( rangeField );
  }
  QString minorityFieldName;
  if ( mStatistics & QgsZonalStatistics::Minority )
  {
    minorityFieldName = getUniqueFieldName( mAttributePrefix + "minority", newFieldList );
    QgsField minorityField( minorityFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( minorityField );
  }
  QString majorityFieldName;
  if ( mStatistics & QgsZonalStatistics::Majority )
  {
    majorityFieldName = getUniqueFieldName( mAttributePrefix + "majority", newFieldList );
    QgsField majField( majorityFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( majField );
  }
  QString varietyFieldName;
  if ( mStatistics & QgsZonalStatistics::Variety )
  {
    varietyFieldName = getUniqueFieldName( mAttributePrefix + "variety", newFieldList );
    QgsField varietyField( varietyFieldName, QVariant::Int, QStringLiteral( "int" ) );
    newFieldList.push_back( varietyField );
  }
  QString varianceFieldName;
  if ( mStatistics & QgsZonalStatistics::Variance )
  {
    varianceFieldName = getUniqueFieldName( mAttributePrefix + "variance", newFieldList );
    QgsField varianceField( varianceFieldName, QVariant::Double, QStringLiteral( "double precision" ) );
    newFieldList.push_back( varianceField );
  }
  vectorProvider->addAttributes( newFieldList );

  //index of the new fields
  int countIndex = mStatistics & QgsZonalStatistics::Count ? vectorProvider->fieldNameIndex( countFieldName ) : -1;
  int sumIndex = mStatistics & QgsZonalStatistics::Sum ? vectorProvider->fieldNameIndex( sumFieldName ) : -1;
  int meanIndex = mStatistics & QgsZonalStatistics::Mean ? vectorProvider->fieldNameIndex( meanFieldName ) : -1;
  int medianIndex = mStatistics & QgsZonalStatistics::Median ? vectorProvider->fieldNameIndex( medianFieldName ) : -1;
  int stdevIndex = mStatistics & QgsZonalStatistics::StDev ? vectorProvider->fieldNameIndex( stdevFieldName ) : -1;
  int minIndex = mStatistics & QgsZonalStatistics::Min ? vectorProvider->fieldNameIndex( minFieldName ) : -1;
  int maxIndex = mStatistics & QgsZonalStatistics::Max ? vectorProvider->fieldNameIndex( maxFieldName ) : -1;
  int rangeIndex = mStatistics & QgsZonalStatistics::Range ? vectorProvider->fieldNameIndex( rangeFieldName ) : -1;
  int minorityIndex = mStatistics & QgsZonalStatistics::Minority ? vectorProvider->fieldNameIndex( minorityFieldName ) : -1;
  int majorityIndex = mStatistics & QgsZonalStatistics::Majority ? vectorProvider->fieldNameIndex( majorityFieldName ) : -1;
  int varietyIndex = mStatistics & QgsZonalStatistics::Variety ? vectorProvider->fieldNameIndex( varietyFieldName ) : -1;
  int varianceIndex = mStatistics & QgsZonalStatistics::Variance ? vectorProvider->fieldNameIndex( varianceFieldName ) : -1;

  if ( ( mStatistics & QgsZonalStatistics::Count && countIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Sum && sumIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Mean && meanIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Median && medianIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::StDev && stdevIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Min && minIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Max && maxIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Range && rangeIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Minority && minorityIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Majority && majorityIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Variety && varietyIndex == -1 )
       || ( mStatistics & QgsZonalStatistics::Variance && varianceIndex == -1 )
     )
  {
    //failed to create a required field
    return 8;
  }

  //progress dialog
  long featureCount = vectorProvider->featureCount();

  //iterate over each polygon
  QgsFeatureRequest request;
  request.setSubsetOfAttributes( QgsAttributeList() );
  QgsFeatureIterator fi = vectorProvider->getFeatures( request );
  QgsFeature f;

  bool statsStoreValues = ( mStatistics & QgsZonalStatistics::Median ) ||
                          ( mStatistics & QgsZonalStatistics::StDev ) ||
                          ( mStatistics & QgsZonalStatistics::Variance );
  bool statsStoreValueCount = ( mStatistics & QgsZonalStatistics::Minority ) ||
                              ( mStatistics & QgsZonalStatistics::Majority );

  FeatureStats featureStats( statsStoreValues, statsStoreValueCount );
  int featureCounter = 0;

  QgsChangedAttributesMap changeMap;
  while ( fi.nextFeature( f ) )
  {
    if ( feedback && feedback->isCanceled() )
    {
      break;
    }

    if ( feedback )
    {
      feedback->setProgress( 100.0 * static_cast< double >( featureCounter ) / featureCount );
    }

    if ( !f.hasGeometry() )
    {
      ++featureCounter;
      continue;
    }
    QgsGeometry featureGeometry = f.geometry();

    QgsRectangle featureRect = featureGeometry.boundingBox().intersect( &rasterBBox );
    if ( featureRect.isEmpty() )
    {
      ++featureCounter;
      continue;
    }

    int offsetX, offsetY, nCellsX, nCellsY;
    if ( cellInfoForBBox( rasterBBox, featureRect, cellsizeX, cellsizeY, offsetX, offsetY, nCellsX, nCellsY ) != 0 )
    {
      ++featureCounter;
      continue;
    }

    //avoid access to cells outside of the raster (may occur because of rounding)
    if ( ( offsetX + nCellsX ) > nCellsXProvider )
    {
      nCellsX = nCellsXProvider - offsetX;
    }
    if ( ( offsetY + nCellsY ) > nCellsYProvider )
    {
      nCellsY = nCellsYProvider - offsetY;
    }

    statisticsFromMiddlePointTest( featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
                                   rasterBBox, featureStats );

    if ( featureStats.count <= 1 )
    {
      //the cell resolution is probably larger than the polygon area. We switch to precise pixel - polygon intersection in this case
      statisticsFromPreciseIntersection( featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
                                         rasterBBox, featureStats );
    }

    //write the statistics value to the vector data provider
    QgsAttributeMap changeAttributeMap;
    if ( mStatistics & QgsZonalStatistics::Count )
      changeAttributeMap.insert( countIndex, QVariant( featureStats.count ) );
    if ( mStatistics & QgsZonalStatistics::Sum )
      changeAttributeMap.insert( sumIndex, QVariant( featureStats.sum ) );
    if ( featureStats.count > 0 )
    {
      double mean = featureStats.sum / featureStats.count;
      if ( mStatistics & QgsZonalStatistics::Mean )
        changeAttributeMap.insert( meanIndex, QVariant( mean ) );
      if ( mStatistics & QgsZonalStatistics::Median )
      {
        std::sort( featureStats.values.begin(), featureStats.values.end() );
        int size =  featureStats.values.count();
        bool even = ( size % 2 ) < 1;
        double medianValue;
        if ( even )
        {
          medianValue = ( featureStats.values.at( size / 2 - 1 ) + featureStats.values.at( size / 2 ) ) / 2;
        }
        else //odd
        {
          medianValue = featureStats.values.at( ( size + 1 ) / 2 - 1 );
        }
        changeAttributeMap.insert( medianIndex, QVariant( medianValue ) );
      }
      if ( mStatistics & QgsZonalStatistics::StDev || mStatistics & QgsZonalStatistics::Variance )
      {
        double sumSquared = 0;
        for ( int i = 0; i < featureStats.values.count(); ++i )
        {
          double diff = featureStats.values.at( i ) - mean;
          sumSquared += diff * diff;
        }
        double variance = sumSquared / featureStats.values.count();
        if ( mStatistics & QgsZonalStatistics::StDev )
        {
          double stdev = std::pow( variance, 0.5 );
          changeAttributeMap.insert( stdevIndex, QVariant( stdev ) );
        }
        if ( mStatistics & QgsZonalStatistics::Variance )
          changeAttributeMap.insert( varianceIndex, QVariant( variance ) );
      }
      if ( mStatistics & QgsZonalStatistics::Min )
        changeAttributeMap.insert( minIndex, QVariant( featureStats.min ) );
      if ( mStatistics & QgsZonalStatistics::Max )
        changeAttributeMap.insert( maxIndex, QVariant( featureStats.max ) );
      if ( mStatistics & QgsZonalStatistics::Range )
        changeAttributeMap.insert( rangeIndex, QVariant( featureStats.max - featureStats.min ) );
      if ( mStatistics & QgsZonalStatistics::Minority || mStatistics & QgsZonalStatistics::Majority )
      {
        QList<int> vals = featureStats.valueCount.values();
        std::sort( vals.begin(), vals.end() );
        if ( mStatistics & QgsZonalStatistics::Minority )
        {
          float minorityKey = featureStats.valueCount.key( vals.first() );
          changeAttributeMap.insert( minorityIndex, QVariant( minorityKey ) );
        }
        if ( mStatistics & QgsZonalStatistics::Majority )
        {
          float majKey = featureStats.valueCount.key( vals.last() );
          changeAttributeMap.insert( majorityIndex, QVariant( majKey ) );
        }
      }
      if ( mStatistics & QgsZonalStatistics::Variety )
        changeAttributeMap.insert( varietyIndex, QVariant( featureStats.valueCount.count() ) );
    }

    changeMap.insert( f.id(), changeAttributeMap );
    ++featureCounter;
  }

  vectorProvider->changeAttributeValues( changeMap );

  if ( feedback )
  {
    feedback->setProgress( 100 );
  }

  mPolygonLayer->updateFields();

  if ( feedback && feedback->isCanceled() )
  {
    return 9;
  }

  return 0;
}
Esempio n. 3
0
int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )
{
  if ( !mPolygonLayer || mPolygonLayer->geometryType() != QGis::Polygon )
  {
    return 1;
  }

  QgsVectorDataProvider* vectorProvider = mPolygonLayer->dataProvider();
  if ( !vectorProvider )
  {
    return 2;
  }

  //open the raster layer and the raster band
  GDALAllRegister();
  GDALDatasetH inputDataset = GDALOpen( TO8F( mRasterFilePath ), GA_ReadOnly );
  if ( !inputDataset )
  {
    return 3;
  }

  if ( GDALGetRasterCount( inputDataset ) < ( mRasterBand - 1 ) )
  {
    GDALClose( inputDataset );
    return 4;
  }

  GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset, mRasterBand );
  if ( !rasterBand )
  {
    GDALClose( inputDataset );
    return 5;
  }
  mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, nullptr );

  //get geometry info about raster layer
  int nCellsXGDAL = GDALGetRasterXSize( inputDataset );
  int nCellsYGDAL = GDALGetRasterYSize( inputDataset );
  double geoTransform[6];
  if ( GDALGetGeoTransform( inputDataset, geoTransform ) != CE_None )
  {
    GDALClose( inputDataset );
    return 6;
  }
  double cellsizeX = geoTransform[1];
  if ( cellsizeX < 0 )
  {
    cellsizeX = -cellsizeX;
  }
  double cellsizeY = geoTransform[5];
  if ( cellsizeY < 0 )
  {
    cellsizeY = -cellsizeY;
  }
  QgsRectangle rasterBBox( geoTransform[0], geoTransform[3] - ( nCellsYGDAL * cellsizeY ),
                           geoTransform[0] + ( nCellsXGDAL * cellsizeX ), geoTransform[3] );

  //add the new fields to the provider
  QList<QgsField> newFieldList;
  QString countFieldName;
  if ( mStatistics & QgsZonalStatistics::Count )
  {
    countFieldName = getUniqueFieldName( mAttributePrefix + "count" );
    QgsField countField( countFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( countField );
  }
  QString sumFieldName;
  if ( mStatistics & QgsZonalStatistics::Sum )
  {
    sumFieldName = getUniqueFieldName( mAttributePrefix + "sum" );
    QgsField sumField( sumFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( sumField );
  }
  QString meanFieldName;
  if ( mStatistics & QgsZonalStatistics::Mean )
  {
    meanFieldName = getUniqueFieldName( mAttributePrefix + "mean" );
    QgsField meanField( meanFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( meanField );
  }
  QString medianFieldName;
  if ( mStatistics & QgsZonalStatistics::Median )
  {
    medianFieldName = getUniqueFieldName( mAttributePrefix + "median" );
    QgsField medianField( medianFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( medianField );
  }
  QString stdevFieldName;
  if ( mStatistics & QgsZonalStatistics::StDev )
  {
    stdevFieldName = getUniqueFieldName( mAttributePrefix + "stdev" );
    QgsField stdField( stdevFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( stdField );
  }
  QString minFieldName;
  if ( mStatistics & QgsZonalStatistics::Min )
  {
    minFieldName = getUniqueFieldName( mAttributePrefix + "min" );
    QgsField minField( minFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( minField );
  }
  QString maxFieldName;
  if ( mStatistics & QgsZonalStatistics::Max )
  {
    maxFieldName = getUniqueFieldName( mAttributePrefix + "max" );
    QgsField maxField( maxFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( maxField );
  }
  QString rangeFieldName;
  if ( mStatistics & QgsZonalStatistics::Range )
  {
    rangeFieldName = getUniqueFieldName( mAttributePrefix + "range" );
    QgsField rangeField( rangeFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( rangeField );
  }
  QString minorityFieldName;
  if ( mStatistics & QgsZonalStatistics::Minority )
  {
    minorityFieldName = getUniqueFieldName( mAttributePrefix + "minority" );
    QgsField minorityField( minorityFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( minorityField );
  }
  QString majorityFieldName;
  if ( mStatistics & QgsZonalStatistics::Majority )
  {
    majorityFieldName = getUniqueFieldName( mAttributePrefix + "majority" );
    QgsField majField( majorityFieldName, QVariant::Double, "double precision" );
    newFieldList.push_back( majField );
  }
  QString varietyFieldName;
  if ( mStatistics & QgsZonalStatistics::Variety )
  {
    varietyFieldName = getUniqueFieldName( mAttributePrefix + "variety" );
    QgsField varietyField( varietyFieldName, QVariant::Int, "int" );
    newFieldList.push_back( varietyField );
  }
  vectorProvider->addAttributes( newFieldList );

  //index of the new fields
  int countIndex = mStatistics & QgsZonalStatistics::Count ? vectorProvider->fieldNameIndex( countFieldName ) : -1;
  int sumIndex = mStatistics & QgsZonalStatistics::Sum ? vectorProvider->fieldNameIndex( sumFieldName ) : -1;
  int meanIndex = mStatistics & QgsZonalStatistics::Mean ? vectorProvider->fieldNameIndex( meanFieldName ) : -1;
  int medianIndex = mStatistics & QgsZonalStatistics::Median ? vectorProvider->fieldNameIndex( medianFieldName ) : -1;
  int stdevIndex = mStatistics & QgsZonalStatistics::StDev ? vectorProvider->fieldNameIndex( stdevFieldName ) : -1;
  int minIndex = mStatistics & QgsZonalStatistics::Min ? vectorProvider->fieldNameIndex( minFieldName ) : -1;
  int maxIndex = mStatistics & QgsZonalStatistics::Max ? vectorProvider->fieldNameIndex( maxFieldName ) : -1;
  int rangeIndex = mStatistics & QgsZonalStatistics::Range ? vectorProvider->fieldNameIndex( rangeFieldName ) : -1;
  int minorityIndex = mStatistics & QgsZonalStatistics::Minority ? vectorProvider->fieldNameIndex( minorityFieldName ) : -1;
  int majorityIndex = mStatistics & QgsZonalStatistics::Majority ? vectorProvider->fieldNameIndex( majorityFieldName ) : -1;
  int varietyIndex = mStatistics & QgsZonalStatistics::Variety ? vectorProvider->fieldNameIndex( varietyFieldName ) : -1;

  if (( mStatistics & QgsZonalStatistics::Count && countIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Sum && sumIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Mean && meanIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Median && medianIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::StDev && stdevIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Min && minIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Max && maxIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Range && rangeIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Minority && minorityIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Majority && majorityIndex == -1 )
      || ( mStatistics & QgsZonalStatistics::Variety && varietyIndex == -1 )
     )
  {
    //failed to create a required field
    return 8;
  }

  //progress dialog
  long featureCount = vectorProvider->featureCount();
  if ( p )
  {
    p->setMaximum( featureCount );
  }


  //iterate over each polygon
  QgsFeatureRequest request;
  request.setSubsetOfAttributes( QgsAttributeList() );
  QgsFeatureIterator fi = vectorProvider->getFeatures( request );
  QgsFeature f;

  bool statsStoreValues = ( mStatistics & QgsZonalStatistics::Median ) ||
                          ( mStatistics & QgsZonalStatistics::StDev );
  bool statsStoreValueCount = ( mStatistics & QgsZonalStatistics::Minority ) ||
                              ( mStatistics & QgsZonalStatistics::Majority );

  FeatureStats featureStats( statsStoreValues, statsStoreValueCount );
  int featureCounter = 0;

  QgsChangedAttributesMap changeMap;
  while ( fi.nextFeature( f ) )
  {
    if ( p )
    {
      p->setValue( featureCounter );
    }

    if ( p && p->wasCanceled() )
    {
      break;
    }

    if ( !f.constGeometry() )
    {
      ++featureCounter;
      continue;
    }
    const QgsGeometry* featureGeometry = f.constGeometry();

    QgsRectangle featureRect = featureGeometry->boundingBox().intersect( &rasterBBox );
    if ( featureRect.isEmpty() )
    {
      ++featureCounter;
      continue;
    }

    int offsetX, offsetY, nCellsX, nCellsY;
    if ( cellInfoForBBox( rasterBBox, featureRect, cellsizeX, cellsizeY, offsetX, offsetY, nCellsX, nCellsY ) != 0 )
    {
      ++featureCounter;
      continue;
    }

    //avoid access to cells outside of the raster (may occur because of rounding)
    if (( offsetX + nCellsX ) > nCellsXGDAL )
    {
      nCellsX = nCellsXGDAL - offsetX;
    }
    if (( offsetY + nCellsY ) > nCellsYGDAL )
    {
      nCellsY = nCellsYGDAL - offsetY;
    }

    statisticsFromMiddlePointTest( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
                                   rasterBBox, featureStats );

    if ( featureStats.count <= 1 )
    {
      //the cell resolution is probably larger than the polygon area. We switch to precise pixel - polygon intersection in this case
      statisticsFromPreciseIntersection( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
                                         rasterBBox, featureStats );
    }

    //write the statistics value to the vector data provider
    QgsAttributeMap changeAttributeMap;
    if ( mStatistics & QgsZonalStatistics::Count )
      changeAttributeMap.insert( countIndex, QVariant( featureStats.count ) );
    if ( mStatistics & QgsZonalStatistics::Sum )
      changeAttributeMap.insert( sumIndex, QVariant( featureStats.sum ) );
    if ( featureStats.count > 0 )
    {
      double mean = featureStats.sum / featureStats.count;
      if ( mStatistics & QgsZonalStatistics::Mean )
        changeAttributeMap.insert( meanIndex, QVariant( mean ) );
      if ( mStatistics & QgsZonalStatistics::Median )
      {
        qSort( featureStats.values.begin(), featureStats.values.end() );
        int size =  featureStats.values.count();
        bool even = ( size % 2 ) < 1;
        double medianValue;
        if ( even )
        {
          medianValue = ( featureStats.values.at( size / 2 - 1 ) + featureStats.values.at( size / 2 ) ) / 2;
        }
        else //odd
        {
          medianValue = featureStats.values.at(( size + 1 ) / 2 - 1 );
        }
        changeAttributeMap.insert( medianIndex, QVariant( medianValue ) );
      }
      if ( mStatistics & QgsZonalStatistics::StDev )
      {
        double sumSquared = 0;
        for ( int i = 0; i < featureStats.values.count(); ++i )
        {
          double diff = featureStats.values.at( i ) - mean;
          sumSquared += diff * diff;
        }
        double stdev = qPow( sumSquared / featureStats.values.count(), 0.5 );
        changeAttributeMap.insert( stdevIndex, QVariant( stdev ) );
      }
      if ( mStatistics & QgsZonalStatistics::Min )
        changeAttributeMap.insert( minIndex, QVariant( featureStats.min ) );
      if ( mStatistics & QgsZonalStatistics::Max )
        changeAttributeMap.insert( maxIndex, QVariant( featureStats.max ) );
      if ( mStatistics & QgsZonalStatistics::Range )
        changeAttributeMap.insert( rangeIndex, QVariant( featureStats.max - featureStats.min ) );
      if ( mStatistics & QgsZonalStatistics::Minority || mStatistics & QgsZonalStatistics::Majority )
      {
        QList<int> vals = featureStats.valueCount.values();
        qSort( vals.begin(), vals.end() );
        if ( mStatistics & QgsZonalStatistics::Minority )
        {
          float minorityKey = featureStats.valueCount.key( vals.first() );
          changeAttributeMap.insert( minorityIndex, QVariant( minorityKey ) );
        }
        if ( mStatistics & QgsZonalStatistics::Majority )
        {
          float majKey = featureStats.valueCount.key( vals.last() );
          changeAttributeMap.insert( majorityIndex, QVariant( majKey ) );
        }
      }
      if ( mStatistics & QgsZonalStatistics::Variety )
        changeAttributeMap.insert( varietyIndex, QVariant( featureStats.valueCount.count() ) );
    }

    changeMap.insert( f.id(), changeAttributeMap );
    ++featureCounter;
  }

  vectorProvider->changeAttributeValues( changeMap );

  if ( p )
  {
    p->setValue( featureCount );
  }

  GDALClose( inputDataset );
  mPolygonLayer->updateFields();

  if ( p && p->wasCanceled() )
  {
    return 9;
  }

  return 0;
}