26QString QgsNearestNeighbourAnalysisAlgorithm::name()
const
28 return QStringLiteral(
"nearestneighbouranalysis" );
31QString QgsNearestNeighbourAnalysisAlgorithm::displayName()
const
33 return QObject::tr(
"Nearest neighbour analysis" );
36QStringList QgsNearestNeighbourAnalysisAlgorithm::tags()
const
38 return QObject::tr(
"point,node,vertex,nearest,neighbour,distance" ).split(
',' );
41QString QgsNearestNeighbourAnalysisAlgorithm::group()
const
43 return QObject::tr(
"Vector analysis" );
46QString QgsNearestNeighbourAnalysisAlgorithm::groupId()
const
48 return QStringLiteral(
"vectoranalysis" );
51QString QgsNearestNeighbourAnalysisAlgorithm::shortHelpString()
const
53 return QObject::tr(
"This algorithm performs nearest neighbor analysis for a point layer.\n\n"
54 "The output describes how the data are distributed (clustered, randomly or distributed).\n\n"
55 "Output is generated as an HTML file with the computed statistical values." );
58QString QgsNearestNeighbourAnalysisAlgorithm::svgIconPath()
const
63QIcon QgsNearestNeighbourAnalysisAlgorithm::icon()
const
68QgsNearestNeighbourAnalysisAlgorithm *QgsNearestNeighbourAnalysisAlgorithm::createInstance()
const
70 return new QgsNearestNeighbourAnalysisAlgorithm();
73void QgsNearestNeighbourAnalysisAlgorithm::initAlgorithm(
const QVariantMap & )
77 QObject::tr(
"HTML files (*.html *.HTML)" ), QVariant(),
true ) );
87 std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral(
"INPUT" ), context ) );
91 const QString outputFile = parameterAsFileOutput( parameters, QStringLiteral(
"OUTPUT_HTML_FILE" ), context );
98 const double step = source->featureCount() ? 100.0 / source->featureCount() : 1;
103 double sumDist = 0.0;
104 const double area = source->sourceExtent().width() * source->sourceExtent().height();
129 const long long count = source->featureCount() > 0 ? source->featureCount() : 1;
130 const double observedDistance = sumDist / count;
131 const double expectedDistance = 0.5 / std::sqrt( count / area );
132 const double nnIndex = observedDistance / expectedDistance;
133 const double se = 0.26136 / std::sqrt( std::pow( count, 2 ) / area );
134 const double zScore = ( observedDistance - expectedDistance ) / se;
137 outputs.insert( QStringLiteral(
"OBSERVED_MD" ), observedDistance );
138 outputs.insert( QStringLiteral(
"EXPECTED_MD" ), expectedDistance );
139 outputs.insert( QStringLiteral(
"NN_INDEX" ), nnIndex );
140 outputs.insert( QStringLiteral(
"POINT_COUNT" ), count );
141 outputs.insert( QStringLiteral(
"Z_SCORE" ), zScore );
143 if ( !outputFile.isEmpty() )
145 QFile file( outputFile );
146 if ( file.open( QIODevice::WriteOnly | QIODevice::Truncate ) )
148 QTextStream out( &file );
149#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
150 out.setCodec(
"UTF-8" );
152 out << QStringLiteral(
"<html><head><meta http-equiv=\"Content-Type\" content=\"text/html;charset=utf-8\"/></head><body>\n" );
153 out << QObject::tr(
"<p>Observed mean distance: %1</p>\n" ).arg( observedDistance, 0,
'f', 11 );
154 out << QObject::tr(
"<p>Expected mean distance: %1</p>\n" ).arg( expectedDistance, 0,
'f', 11 );
155 out << QObject::tr(
"<p>Nearest neighbour index: %1</p>\n" ).arg( nnIndex, 0,
'f', 11 );
156 out << QObject::tr(
"<p>Number of points: %1</p>\n" ).arg( count );
157 out << QObject::tr(
"<p>Z-Score: %1</p>\n" ).arg( zScore, 0,
'f', 11 );
158 out << QStringLiteral(
"</body></html>" );
160 outputs.insert( QStringLiteral(
"OUTPUT_HTML_FILE" ), outputFile );
@ VectorPoint
Vector point layers.
static QIcon getThemeIcon(const QString &name, const QColor &fillColor=QColor(), const QColor &strokeColor=QColor())
Helper to get a theme icon.
static QString iconPath(const QString &iconFile)
Returns path to the desired icon file.
Custom exception class for Coordinate Reference System related exceptions.
A general purpose distance and area calculator, capable of performing ellipsoid based calculations.
double measureLine(const QVector< QgsPointXY > &points) const
Measures the length of a line with multiple segments.
void setSourceCrs(const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context)
Sets source spatial reference system crs.
bool setEllipsoid(const QString &ellipsoid)
Sets the ellipsoid by its acronym.
Wrapper for iterator of features from vector data provider or vector layer.
bool nextFeature(QgsFeature &f)
Fetch next feature and stores in f, returns true on success.
This class wraps a request for features to a vector layer (or directly its vector data provider).
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
bool isCanceled() const
Tells whether the operation has been canceled already.
void setProgress(double progress)
Sets the current progress for the feedback object.
QgsPointXY asPoint() const
Returns the contents of the geometry as a 2-dimensional point.
Contains information about the context in which a processing algorithm is executed.
QgsCoordinateTransformContext transformContext() const
Returns the coordinate transform context.
QString ellipsoid() const
Returns the ellipsoid to use for distance and area calculations.
Custom exception class for processing related exceptions.
Base class for providing feedback from a processing algorithm.
A numeric output for processing algorithms.
An input feature source (such as vector layers) parameter for processing algorithms.
A generic file based destination parameter, for specifying the destination path for a file (non-map l...
A spatial index for QgsFeature objects.
@ FlagStoreFeatureGeometries
Indicates that the spatial index should also store feature geometries. This requires more memory,...
qint64 QgsFeatureId
64 bit feature ids negative numbers are used for uncommitted/newly added features