QMap<QString, QString> QgsRasterDataProvider::identify( const QgsPoint & thePoint, const QgsRectangle &theExtent, int theWidth, int theHeight )
{
QMap<QString, QString> results;
QgsRasterDataProvider::IdentifyFormat identifyFormat;
if ( capabilities() & QgsRasterDataProvider::IdentifyValue )
{
identifyFormat = QgsRasterDataProvider::IdentifyFormatValue;
}
else if ( capabilities() & QgsRasterDataProvider::IdentifyHtml )
{
identifyFormat = QgsRasterDataProvider::IdentifyFormatHtml;
}
else if ( capabilities() & QgsRasterDataProvider::IdentifyText )
{
identifyFormat = QgsRasterDataProvider::IdentifyFormatText;
}
else
{
return results;
}
QMap<int, QVariant> myResults = identify( thePoint, identifyFormat, theExtent, theWidth, theHeight );
if ( identifyFormat == QgsRasterDataProvider::IdentifyFormatValue )
{
foreach ( int bandNo, myResults.keys() )
{
double value = myResults.value( bandNo ).toDouble();
QString valueString;
if ( isNoDataValue( bandNo, value ) )
{
valueString = tr( "no data" );
}
else
{
valueString = QgsRasterBlock::printValue( value );
}
results.insert( generateBandName( bandNo ), valueString );
}
}
QgsRasterBandStats QgsRasterDataProvider::bandStatistics( int theBandNo )
{
double myNoDataValue = noDataValue();
QgsRasterBandStats myRasterBandStats;
myRasterBandStats.elementCount = 0; // because we'll be counting only VALID pixels later
myRasterBandStats.bandName = generateBandName( theBandNo );
myRasterBandStats.bandNumber = theBandNo;
int myDataType = dataType( theBandNo );
int myNXBlocks, myNYBlocks, myXBlockSize, myYBlockSize;
myXBlockSize = xBlockSize();
myYBlockSize = yBlockSize();
myNXBlocks = ( xSize() + myXBlockSize - 1 ) / myXBlockSize;
myNYBlocks = ( ySize() + myYBlockSize - 1 ) / myYBlockSize;
void *myData = CPLMalloc( myXBlockSize * myYBlockSize * ( dataTypeSize( theBandNo ) / 8 ) );
// unfortunately we need to make two passes through the data to calculate stddev
bool myFirstIterationFlag = true;
int myBandXSize = xSize();
int myBandYSize = ySize();
for ( int iYBlock = 0; iYBlock < myNYBlocks; iYBlock++ )
{
for ( int iXBlock = 0; iXBlock < myNXBlocks; iXBlock++ )
{
int nXValid, nYValid;
readBlock( theBandNo, iXBlock, iYBlock, myData );
// Compute the portion of the block that is valid
// for partial edge blocks.
if (( iXBlock + 1 ) * myXBlockSize > myBandXSize )
nXValid = myBandXSize - iXBlock * myXBlockSize;
else
nXValid = myXBlockSize;
if (( iYBlock + 1 ) * myYBlockSize > myBandYSize )
nYValid = myBandYSize - iYBlock * myYBlockSize;
else
nYValid = myYBlockSize;
// Collect the histogram counts.
for ( int iY = 0; iY < nYValid; iY++ )
{
for ( int iX = 0; iX < nXValid; iX++ )
{
double myValue = readValue( myData, myDataType, iX + ( iY * myXBlockSize ) );
//QgsDebugMsg ( QString ( "%1 %2 value %3" ).arg (iX).arg(iY).arg( myValue ) );
if ( mValidNoDataValue && ( qAbs( myValue - myNoDataValue ) <= TINY_VALUE ) )
{
continue; // NULL
}
myRasterBandStats.sum += myValue;
++myRasterBandStats.elementCount;
//only use this element if we have a non null element
if ( myFirstIterationFlag )
{
//this is the first iteration so initialise vars
myFirstIterationFlag = false;
myRasterBandStats.minimumValue = myValue;
myRasterBandStats.maximumValue = myValue;
} //end of true part for first iteration check
else
{
//this is done for all subsequent iterations
if ( myValue < myRasterBandStats.minimumValue )
{
myRasterBandStats.minimumValue = myValue;
}
if ( myValue > myRasterBandStats.maximumValue )
{
myRasterBandStats.maximumValue = myValue;
}
} //end of false part for first iteration check
}
}
} //end of column wise loop
} //end of row wise loop
//end of first pass through data now calculate the range
myRasterBandStats.range = myRasterBandStats.maximumValue - myRasterBandStats.minimumValue;
//calculate the mean
myRasterBandStats.mean = myRasterBandStats.sum / myRasterBandStats.elementCount;
//for the second pass we will get the sum of the squares / mean
for ( int iYBlock = 0; iYBlock < myNYBlocks; iYBlock++ )
{
for ( int iXBlock = 0; iXBlock < myNXBlocks; iXBlock++ )
{
int nXValid, nYValid;
readBlock( theBandNo, iXBlock, iYBlock, myData );
// Compute the portion of the block that is valid
// for partial edge blocks.
if (( iXBlock + 1 ) * myXBlockSize > myBandXSize )
nXValid = myBandXSize - iXBlock * myXBlockSize;
else
nXValid = myXBlockSize;
if (( iYBlock + 1 ) * myYBlockSize > myBandYSize )
nYValid = myBandYSize - iYBlock * myYBlockSize;
else
nYValid = myYBlockSize;
// Collect the histogram counts.
for ( int iY = 0; iY < nYValid; iY++ )
{
for ( int iX = 0; iX < nXValid; iX++ )
{
double myValue = readValue( myData, myDataType, iX + ( iY * myXBlockSize ) );
//QgsDebugMsg ( "myValue = " + QString::number(myValue) );
if ( mValidNoDataValue && ( qAbs( myValue - myNoDataValue ) <= TINY_VALUE ) )
{
continue; // NULL
}
myRasterBandStats.sumOfSquares += static_cast < double >
( pow( myValue - myRasterBandStats.mean, 2 ) );
}
}
} //end of column wise loop
} //end of row wise loop
//divide result by sample size - 1 and get square root to get stdev
myRasterBandStats.stdDev = static_cast < double >( sqrt( myRasterBandStats.sumOfSquares /
( myRasterBandStats.elementCount - 1 ) ) );
#ifdef QGISDEBUG
QgsLogger::debug( "************ STATS **************", 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "VALID NODATA", mValidNoDataValue, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "NULL", noDataValue() , 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "MIN", myRasterBandStats.minimumValue, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "MAX", myRasterBandStats.maximumValue, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "RANGE", myRasterBandStats.range, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "MEAN", myRasterBandStats.mean, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "STDDEV", myRasterBandStats.stdDev, 1, __FILE__, __FUNCTION__, __LINE__ );
#endif
CPLFree( myData );
myRasterBandStats.statsGathered = true;
return myRasterBandStats;
}
