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fix use of Mersenne Twister in random raster alg
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@root676 @nyalldawson
root676 authored and nyalldawson committed Apr 20, 2020
1 parent 9405b44 commit f3aa8af
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Showing 2 changed files with 13 additions and 15 deletions.
24 changes: 13 additions & 11 deletions src/analysis/processing/qgsalgorithmrandomraster.cpp
View file
Expand Up @@ -186,16 +186,18 @@ bool QgsRandomRasterAlgorithm::prepareAlgorithm( const QVariantMap &parameters,
default:
break;
}

mRandomIntDistribution = std::uniform_int_distribution<long>( mRandomLowerBound, mRandomUpperBound );
mRandomDoubleDistribution = std::uniform_real_distribution<double>( mRandomLowerBound, mRandomUpperBound );

return true;
}


QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
{
std::random_device rd {};
std::mt19937 mersenneTwister{rd()};

std::uniform_int_distribution<long> randomIntDistribution = std::uniform_int_distribution<long>( mRandomLowerBound, mRandomUpperBound );
std::uniform_real_distribution<double> randomDoubleDistribution = std::uniform_real_distribution<double>( mRandomLowerBound, mRandomUpperBound );

const QString outputFile = parameterAsOutputLayer( parameters, QStringLiteral( "OUTPUT" ), context );
QFileInfo fi( outputFile );
const QString outputFormat = QgsRasterFileWriter::driverForExtension( fi.suffix() );
Expand Down Expand Up @@ -233,7 +235,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<quint8> byteRow( cols );
for ( int col = 0; col < cols; col++ )
{
byteRow[col] = static_cast<quint8>( mRandomIntDistribution( mRandomDevice ) );
byteRow[col] = static_cast<quint8>( randomIntDistribution( mersenneTwister ) );
}
block.setData( QByteArray( reinterpret_cast<const char *>( byteRow.data() ), QgsRasterBlock::typeSize( Qgis::Byte ) * cols ) );
break;
Expand All @@ -243,7 +245,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<qint16> int16Row( cols );
for ( int col = 0; col < cols; col++ )
{
int16Row[col] = static_cast<qint16>( mRandomIntDistribution( mRandomDevice ) );
int16Row[col] = static_cast<qint16>( randomIntDistribution( mersenneTwister ) );
}
block.setData( QByteArray( reinterpret_cast<const char *>( int16Row.data() ), QgsRasterBlock::typeSize( Qgis::Int16 ) * cols ) );
break;
Expand All @@ -253,7 +255,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<quint16> uInt16Row( cols );
for ( int col = 0; col < cols; col++ )
{
uInt16Row[col] = static_cast<quint16>( mRandomIntDistribution( mRandomDevice ) );
uInt16Row[col] = static_cast<quint16>( randomIntDistribution( mersenneTwister ) );
}
block.setData( QByteArray( reinterpret_cast<const char *>( uInt16Row.data() ), QgsRasterBlock::typeSize( Qgis::UInt16 ) * cols ) );
break;
Expand All @@ -263,7 +265,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<qint32> int32Row( cols );
for ( int col = 0; col < cols; col++ )
{
int32Row[col] = static_cast<qint32>( mRandomIntDistribution( mRandomDevice ) );
int32Row[col] = static_cast<qint32>( randomIntDistribution( mersenneTwister ) );
}
block.setData( QByteArray( reinterpret_cast<const char *>( int32Row.data() ), QgsRasterBlock::typeSize( Qgis::Int32 ) * cols ) );
break;
Expand All @@ -273,7 +275,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<quint32> uInt32Row( cols );
for ( int col = 0; col < cols; col++ )
{
uInt32Row[col] = static_cast<quint32>( mRandomIntDistribution( mRandomDevice ) );
uInt32Row[col] = static_cast<quint32>( randomIntDistribution( mersenneTwister ) );
}
block.setData( QByteArray( reinterpret_cast<const char *>( uInt32Row.data() ), QgsRasterBlock::typeSize( Qgis::UInt32 ) * cols ) );
break;
Expand All @@ -283,7 +285,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<float> float32Row( cols );
for ( int col = 0; col < cols; col++ )
{
float32Row[col] = static_cast<float>( mRandomDoubleDistribution( mRandomDevice ) );
float32Row[col] = static_cast<float>( randomDoubleDistribution( mersenneTwister ) );
}
block.setData( QByteArray( reinterpret_cast<const char *>( float32Row.data() ), QgsRasterBlock::typeSize( Qgis::Float32 ) * cols ) );
break;
Expand All @@ -293,7 +295,7 @@ QVariantMap QgsRandomRasterAlgorithm::processAlgorithm( const QVariantMap &param
std::vector<double> float64Row( cols );
for ( int col = 0; col < cols; col++ )
{
float64Row[col] = mRandomDoubleDistribution( mRandomDevice );
float64Row[col] = randomDoubleDistribution( mersenneTwister );
}
block.setData( QByteArray( reinterpret_cast<const char *>( float64Row.data() ), QgsRasterBlock::typeSize( Qgis::Float64 ) * cols ) );
break;
Expand Down
4 changes: 0 additions & 4 deletions src/analysis/processing/qgsalgorithmrandomraster.h
View file
Expand Up @@ -52,13 +52,9 @@ class QgsRandomRasterAlgorithm : public QgsProcessingAlgorithm
double mPixelSize;
Qgis::DataType mRasterDataType;
int mTypeId;
std::random_device mRandomDevice;
std::mt19937 mMersenneTwister;

double mRandomUpperBound;
double mRandomLowerBound;
std::uniform_int_distribution<long> mRandomIntDistribution;
std::uniform_real_distribution<double> mRandomDoubleDistribution;
};

///@endcond PRIVATE
Expand Down

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