C++ QgsVectorDataProvider::changeAttributeValues方法代码示例

//.........这里部分代码省略.........

    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;
}

//.........这里部分代码省略.........
    }
    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;
}

//.........这里部分代码省略.........
  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;
}

bool QgsVectorLayerEditBuffer::commitChanges( QStringList& commitErrors )
{
  QgsVectorDataProvider* provider = L->dataProvider();
  commitErrors.clear();

  int cap = provider->capabilities();
  bool success = true;

  QgsFields oldFields = L->pendingFields();

  //
  // delete attributes
  //
  bool attributesChanged = false;
  if ( !mDeletedAttributeIds.isEmpty() )
  {
    if (( cap & QgsVectorDataProvider::DeleteAttributes ) && provider->deleteAttributes( mDeletedAttributeIds.toSet() ) )
    {
      commitErrors << tr( "SUCCESS: %n attribute(s) deleted.", "deleted attributes count", mDeletedAttributeIds.size() );

      emit committedAttributesDeleted( L->id(), mDeletedAttributeIds );

      mDeletedAttributeIds.clear();
      attributesChanged = true;
    }
    else
    {
      commitErrors << tr( "ERROR: %n attribute(s) not deleted.", "not deleted attributes count", mDeletedAttributeIds.size() );
      success = false;
    }
  }

  //
  // add attributes
  //
  if ( !mAddedAttributes.isEmpty() )
  {
    if (( cap & QgsVectorDataProvider::AddAttributes ) && provider->addAttributes( mAddedAttributes ) )
    {
      commitErrors << tr( "SUCCESS: %n attribute(s) added.", "added attributes count", mAddedAttributes.size() );

      emit committedAttributesAdded( L->id(), mAddedAttributes );

      mAddedAttributes.clear();
      attributesChanged = true;
    }
    else
    {
      commitErrors << tr( "ERROR: %n new attribute(s) not added", "not added attributes count", mAddedAttributes.size() );
      success = false;
    }
  }

  //
  // check that addition/removal went as expected
  //
  bool attributeChangesOk = true;
  if ( attributesChanged )
  {
    L->updateFields();
    QgsFields newFields = L->pendingFields();

    if ( oldFields.count() != newFields.count() )
    {
      commitErrors << tr( "ERROR: the count of fields is incorrect after addition/removal of fields!" );
      attributeChangesOk = false;   // don't try attribute updates - they'll fail.
    }

    for ( int i = 0; i < oldFields.count(); ++i )
    {
      const QgsField& oldField = oldFields[i];
      const QgsField& newField = newFields[i];
      if ( attributeChangesOk && oldField != newField )
      {
        commitErrors << tr( "ERROR: field with index %1 is not the same!" ).arg( i );
        attributeChangesOk = false;   // don't try attribute updates - they'll fail.
      }
    }
  }

  if ( attributeChangesOk )
  {
    //
    // change attributes
    //
    if ( !mChangedAttributeValues.isEmpty() )
    {
      if (( cap & QgsVectorDataProvider::ChangeAttributeValues ) && provider->changeAttributeValues( mChangedAttributeValues ) )
      {
        commitErrors << tr( "SUCCESS: %n attribute value(s) changed.", "changed attribute values count", mChangedAttributeValues.size() );

        emit committedAttributeValuesChanges( L->id(), mChangedAttributeValues );

        mChangedAttributeValues.clear();
      }
      else
      {
        commitErrors << tr( "ERROR: %n attribute value change(s) not applied.", "not changed attribute values count", mChangedAttributeValues.size() );
        success = false;
      }
//.........这里部分代码省略.........