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Rework Select by Location algorithm
Changes: - handle different CRS transparently - don't build a spatial index on the selection layer. Instead only use feature requests to fetch features which are within the desired bounds, and rely on the presence of an appropriate spatial index at the provider's backend. Otherwise, we force every user of this algorithm to have a full iteration of the source table, regardless of how large the table is. That means that trying to select a set of addresses which fall within a specific locality from a table which contains the addresses for a whole state will FORCE every address in the state to be initially read before any calculation begins. With this change only those features within the bounding box of the selected localities will ever be fetched from the provider, resulting in huge speed improvements for the algorithm. - use prepared geometries for the spatial relation tests. This dramatically speeds up the algorithm in the case where the intersection layer features cover multiple features from the 'selection' layer. - Add a 'select within current selection' mode - Optimise feature requests for efficiency (especially with respect to the 'disjoint' selection mode)
This commit is contained in:
Nyall Dawson
parent
20d824413e
commit
24a4ab7f0d
@ -134,6 +134,7 @@ from .Ruggedness import Ruggedness
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from .SaveSelectedFeatures import SaveSelectedFeatures
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from .SelectByAttribute import SelectByAttribute
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from .SelectByExpression import SelectByExpression
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from .SelectByLocation import SelectByLocation
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from .ServiceAreaFromLayer import ServiceAreaFromLayer
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from .ServiceAreaFromPoint import ServiceAreaFromPoint
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from .SetMValue import SetMValue
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@ -167,7 +168,6 @@ from .VoronoiPolygons import VoronoiPolygons
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from .ZonalStatistics import ZonalStatistics
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# from .ExtractByLocation import ExtractByLocation
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# from .SelectByLocation import SelectByLocation
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# from .SpatialJoin import SpatialJoin
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pluginPath = os.path.normpath(os.path.join(
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@ -183,7 +183,6 @@ class QGISAlgorithmProvider(QgsProcessingProvider):
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def getAlgs(self):
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# algs = [
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# SelectByLocation(),
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# ExtractByLocation(),
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# SpatialJoin(),
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# ]
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@ -281,6 +280,7 @@ class QGISAlgorithmProvider(QgsProcessingProvider):
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SaveSelectedFeatures(),
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SelectByAttribute(),
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SelectByExpression(),
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SelectByLocation(),
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ServiceAreaFromLayer(),
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ServiceAreaFromPoint(),
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SetMValue(),
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@ -29,13 +29,19 @@ import os
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import QgsGeometry, QgsFeatureRequest, QgsProcessingUtils
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from qgis.core import (QgsGeometry,
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QgsFeatureRequest,
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QgsProcessingUtils,
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QgsProcessing,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterFeatureSource,
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QgsProcessingParameterEnum,
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QgsProcessingParameterNumber,
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QgsProcessingOutputVectorLayer,
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QgsVectorLayer)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.core.parameters import ParameterSelection
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterNumber
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from processing.core.outputs import OutputVector
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from processing.tools import vector
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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@ -63,32 +69,43 @@ class SelectByLocation(QgisAlgorithm):
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self.predicates = (
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('intersects', self.tr('intersects')),
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('contains', self.tr('contains')),
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('disjoint', self.tr('disjoint')),
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('equals', self.tr('equals')),
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('disjoint', self.tr('is disjoint')),
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('isEqual', self.tr('equals')),
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('touches', self.tr('touches')),
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('overlaps', self.tr('overlaps')),
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('within', self.tr('within')),
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('crosses', self.tr('crosses')))
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self.reversed_predicates = {'intersects': 'intersects',
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'contains': 'within',
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'disjoint': 'disjoint',
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'isEqual': 'isEqual',
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'touches': 'touches',
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'overlaps': 'overlaps',
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'within': 'contains',
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'crosses': 'crosses'}
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self.methods = [self.tr('creating new selection'),
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self.tr('adding to current selection'),
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self.tr('select within current selection'),
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self.tr('removing from current selection')]
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self.addParameter(ParameterVector(self.INPUT,
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self.tr('Layer to select from')))
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self.addParameter(ParameterVector(self.INTERSECT,
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self.tr('Additional layer (intersection layer)')))
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self.addParameter(ParameterSelection(self.PREDICATE,
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self.tr('Geometric predicate'),
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self.predicates,
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multiple=True))
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self.addParameter(ParameterNumber(self.PRECISION,
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self.tr('Precision'),
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0.0, None, 0.0))
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self.addParameter(ParameterSelection(self.METHOD,
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self.tr('Modify current selection by'),
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self.methods, 0))
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self.addOutput(OutputVector(self.OUTPUT, self.tr('Selected (location)'), True))
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self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT,
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self.tr('Select features from'), types=[QgsProcessing.TypeVectorAnyGeometry]))
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self.addParameter(QgsProcessingParameterEnum(self.PREDICATE,
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self.tr('Where the features are (geometric predicate)'),
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options=[p[1] for p in self.predicates],
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allowMultiple=True, defaultValue=[0]))
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self.addParameter(QgsProcessingParameterFeatureSource(self.INTERSECT,
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self.tr('By comparing to the features from'), types=[QgsProcessing.TypeVectorAnyGeometry]))
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self.addParameter(QgsProcessingParameterNumber(self.PRECISION,
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self.tr('Precision'), type=QgsProcessingParameterNumber.Double,
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minValue=0.0, defaultValue=0.0))
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self.addParameter(QgsProcessingParameterEnum(self.METHOD,
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self.tr('Modify current selection by'),
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options=self.methods, defaultValue=0))
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self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Selected (by location)')))
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def name(self):
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return 'selectbylocation'
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@ -97,60 +114,61 @@ class SelectByLocation(QgisAlgorithm):
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return self.tr('Select by location')
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def processAlgorithm(self, parameters, context, feedback):
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filename = self.getParameterValue(self.INPUT)
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inputLayer = QgsProcessingUtils.mapLayerFromString(filename, context)
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method = self.getParameterValue(self.METHOD)
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filename2 = self.getParameterValue(self.INTERSECT)
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selectLayer = QgsProcessingUtils.mapLayerFromString(filename2, context)
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predicates = self.getParameterValue(self.PREDICATE)
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precision = self.getParameterValue(self.PRECISION)
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oldSelection = set(inputLayer.selectedFeatureIds())
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inputLayer.removeSelection()
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index = QgsProcessingUtils.createSpatialIndex(inputLayer, context)
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select_layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
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method = QgsVectorLayer.SelectBehavior(self.parameterAsEnum(parameters, self.METHOD, context))
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intersect_source = self.parameterAsSource(parameters, self.INTERSECT, context)
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# build a list of 'reversed' predicates, because in this function
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# we actually test the reverse of what the user wants (allowing us
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# to prepare geometries and optimise the algorithm)
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predicates = [self.reversed_predicates[self.predicates[i][0]] for i in self.parameterAsEnums(parameters, self.PREDICATE, context)]
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precision = self.parameterAsDouble(parameters, self.PRECISION, context)
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if 'disjoint' in predicates:
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disjoinSet = []
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for feat in QgsProcessingUtils.getFeatures(inputLayer, context):
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disjoinSet.append(feat.id())
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disjoint_set = select_layer.allFeatureIds()
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else:
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disjoint_set = None
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geom = QgsGeometry()
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selectedSet = []
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features = QgsProcessingUtils.getFeatures(selectLayer, context)
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total = 100.0 / selectLayer.featureCount() if selectLayer.featureCount() else 0
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selected_set = set()
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request = QgsFeatureRequest().setSubsetOfAttributes([]).setDestinationCrs(select_layer.crs())
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features = intersect_source.getFeatures(request)
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total = 100.0 / intersect_source.featureCount() if intersect_source.featureCount() else 0
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for current, f in enumerate(features):
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geom = vector.snapToPrecision(f.geometry(), precision)
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bbox = geom.boundingBox()
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if feedback.isCanceled():
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break
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if not f.hasGeometry():
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continue
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engine = QgsGeometry.createGeometryEngine(f.geometry().geometry())
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engine.prepareGeometry()
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bbox = f.geometry().boundingBox()
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bbox.grow(0.51 * precision)
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intersects = index.intersects(bbox)
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request = QgsFeatureRequest().setFilterFids(intersects).setSubsetOfAttributes([])
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for feat in inputLayer.getFeatures(request):
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tmpGeom = vector.snapToPrecision(feat.geometry(), precision)
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request = QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry).setFilterRect(bbox).setSubsetOfAttributes([])
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for test_feat in select_layer.getFeatures(request):
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if feedback.isCanceled():
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break
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if test_feat in selected_set:
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# already added this one, no need for further tests
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continue
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res = False
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for predicate in predicates:
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if predicate == 'disjoint':
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if tmpGeom.intersects(geom):
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if test_feat.geometry().intersects(f.geometry()):
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try:
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disjoinSet.remove(feat.id())
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disjoint_set.remove(test_feat.id())
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except:
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pass # already removed
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else:
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res = getattr(tmpGeom, predicate)(geom)
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if res:
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selectedSet.append(feat.id())
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if getattr(engine, predicate)(test_feat.geometry().geometry()):
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selected_set.add(test_feat.id())
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break
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feedback.setProgress(int(current * total))
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if 'disjoint' in predicates:
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selectedSet = selectedSet + disjoinSet
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selected_set = list(selected_set) + disjoint_set
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if method == 1:
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selectedSet = list(oldSelection.union(selectedSet))
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elif method == 2:
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selectedSet = list(oldSelection.difference(selectedSet))
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inputLayer.selectByIds(selectedSet)
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self.setOutputValue(self.OUTPUT, filename)
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select_layer.selectByIds(list(selected_set), method)
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return {self.OUTPUT: parameters[self.INPUT]}
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