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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
210 lines
8.0 KiB
Python
210 lines
8.0 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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EliminateSelection.py
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---------------------
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Date : January 2017
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Copyright : (C) 2017 by Bernhard Ströbl
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Email : bernhard.stroebl@jena.de
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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from builtins import range
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__author__ = 'Bernhard Ströbl'
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__date__ = 'January 2017'
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__copyright__ = '(C) 2017, Bernhard Ströbl'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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import os
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import (QgsFeatureRequest,
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QgsFeature,
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QgsGeometry,
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QgsMessageLog,
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QgsProcessingUtils)
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterSelection
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class EliminateSelection(GeoAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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MODE = 'MODE'
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MODE_LARGEST_AREA = 0
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MODE_SMALLEST_AREA = 1
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MODE_BOUNDARY = 2
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'eliminate.png'))
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def group(self):
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return self.tr('Vector geometry tools')
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def name(self):
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return 'eliminateselectedpolygons'
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def displayName(self):
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return self.tr('Eliminate selected polygons')
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def defineCharacteristics(self):
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self.modes = [self.tr('Largest area'),
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self.tr('Smallest Area'),
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self.tr('Largest common boundary')]
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self.addParameter(ParameterVector(self.INPUT,
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self.tr('Input layer'), [dataobjects.TYPE_VECTOR_POLYGON]))
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self.addParameter(ParameterSelection(self.MODE,
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self.tr('Merge selection with the neighbouring polygon with the'),
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self.modes))
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self.addOutput(OutputVector(self.OUTPUT, self.tr('Eliminated'), datatype=[dataobjects.TYPE_VECTOR_POLYGON]))
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def processAlgorithm(self, context, feedback):
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inLayer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT), context)
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boundary = self.getParameterValue(self.MODE) == self.MODE_BOUNDARY
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smallestArea = self.getParameterValue(self.MODE) == self.MODE_SMALLEST_AREA
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if inLayer.selectedFeatureCount() == 0:
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QgsMessageLog.logMessage(self.tr('{0}: (No selection in input layer "{1}")').format(self.displayName(), self.getParameterValue(self.INPUT)),
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self.tr('Processing'), QgsMessageLog.WARNING)
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featToEliminate = []
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selFeatIds = inLayer.selectedFeatureIds()
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output = self.getOutputFromName(self.OUTPUT)
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writer = output.getVectorWriter(inLayer.fields(), inLayer.wkbType(), inLayer.crs(), context)
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for aFeat in inLayer.getFeatures():
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if aFeat.id() in selFeatIds:
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# Keep references to the features to eliminate
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featToEliminate.append(aFeat)
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else:
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# write the others to output
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writer.addFeature(aFeat)
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# Delete all features to eliminate in processLayer
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processLayer = output.layer
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processLayer.startEditing()
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# ANALYZE
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if len(featToEliminate) > 0: # Prevent zero division
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start = 20.00
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add = 80.00 / len(featToEliminate)
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else:
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start = 100
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feedback.setProgress(start)
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madeProgress = True
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# We go through the list and see if we find any polygons we can
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# merge the selected with. If we have no success with some we
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# merge and then restart the whole story.
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while madeProgress: # Check if we made any progress
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madeProgress = False
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featNotEliminated = []
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# Iterate over the polygons to eliminate
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for i in range(len(featToEliminate)):
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feat = featToEliminate.pop()
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geom2Eliminate = feat.geometry()
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bbox = geom2Eliminate.boundingBox()
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fit = processLayer.getFeatures(
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QgsFeatureRequest().setFilterRect(bbox).setSubsetOfAttributes([]))
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mergeWithFid = None
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mergeWithGeom = None
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max = 0
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min = -1
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selFeat = QgsFeature()
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# use prepared geometries for faster intersection tests
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engine = QgsGeometry.createGeometryEngine(geom2Eliminate.geometry())
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engine.prepareGeometry()
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while fit.nextFeature(selFeat):
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selGeom = selFeat.geometry()
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if engine.intersects(selGeom.geometry()):
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# We have a candidate
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iGeom = geom2Eliminate.intersection(selGeom)
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if not iGeom:
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continue
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if boundary:
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selValue = iGeom.length()
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else:
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# area. We need a common boundary in
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# order to merge
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if 0 < iGeom.length():
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selValue = selGeom.area()
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else:
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selValue = -1
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if -1 != selValue:
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useThis = True
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if smallestArea:
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if -1 == min:
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min = selValue
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else:
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if selValue < min:
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min = selValue
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else:
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useThis = False
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else:
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if selValue > max:
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max = selValue
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else:
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useThis = False
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if useThis:
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mergeWithFid = selFeat.id()
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mergeWithGeom = QgsGeometry(selGeom)
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# End while fit
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if mergeWithFid is not None:
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# A successful candidate
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newGeom = mergeWithGeom.combine(geom2Eliminate)
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if processLayer.changeGeometry(mergeWithFid, newGeom):
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madeProgress = True
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else:
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raise GeoAlgorithmExecutionException(
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self.tr('Could not replace geometry of feature with id {0}').format(mergeWithFid))
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start = start + add
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feedback.setProgress(start)
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else:
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featNotEliminated.append(feat)
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# End for featToEliminate
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featToEliminate = featNotEliminated
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# End while
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if not processLayer.commitChanges():
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raise GeoAlgorithmExecutionException(self.tr('Could not commit changes'))
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for feature in featNotEliminated:
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writer.addFeature(feature)
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