[processing] add Symetrical difference algorithm (addresses #5953)

python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py

@@ -32,6 +32,7 @@
 
 from processing.core.AlgorithmProvider import AlgorithmProvider
 from ftools.RegularPoints import RegularPoints
+from ftools.SymetricalDifference import SymetricalDifference
 
 from RandomExtract import RandomExtract
 from RandomExtractWithinSubsets import RandomExtractWithinSubsets
@@ -146,7 +147,7 @@ def __init__(self):
                         RandomSelection(), RandomSelectionWithinSubsets(),
                         SelectByLocation(), RandomExtract(),
                         RandomExtractWithinSubsets(), ExtractByLocation(),
-                        SpatialJoin(), RegularPoints(),
+                        SpatialJoin(), RegularPoints(), SymetricalDifference(),
                         DeleteColumn(),
                         DeleteDuplicateGeometries(), TextToFloat(),
                         ExtractByAttribute(), SelectByAttribute(), Grid(),

python/plugins/processing/algs/qgis/ftools/SymetricalDifference.py

@@ -0,0 +1,149 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    SymetricalDifference.py
+    ---------------------
+    Date                 : September 2014
+    Copyright            : (C) 2014 by Alexander Bruy
+    Email                : alexander dot bruy at gmail dot com
+***************************************************************************
+*                                                                         *
+*   This program is free software; you can redistribute it and/or modify  *
+*   it under the terms of the GNU General Public License as published by  *
+*   the Free Software Foundation; either version 2 of the License, or     *
+*   (at your option) any later version.                                   *
+*                                                                         *
+***************************************************************************
+"""
+
+__author__ = 'Alexander Bruy'
+__date__ = 'September 2014'
+__copyright__ = '(C) 2014, Alexander Bruy'
+
+# This will get replaced with a git SHA1 when you do a git archive
+
+__revision__ = '$Format:%H$'
+
+from PyQt4.QtCore import *
+from qgis.core import *
+from processing.core.ProcessingLog import ProcessingLog
+from processing.core.GeoAlgorithm import GeoAlgorithm
+from processing.core.parameters import ParameterVector
+from processing.core.outputs import OutputVector
+from processing.tools import dataobjects, vector
+
+
+class SymetricalDifference(GeoAlgorithm):
+
+    INPUT = 'INPUT'
+    OVERLAY = 'OVERLAY'
+    OUTPUT = 'OUTPUT'
+
+    def defineCharacteristics(self):
+        self.name = 'Symetrical difference'
+        self.group = 'Vector overlay tools'
+        self.addParameter(ParameterVector(self.INPUT, 'Input layer',
+                          [ParameterVector.VECTOR_TYPE_ANY]))
+        self.addParameter(ParameterVector(self.OVERLAY,
+                          'Difference layer',
+                          [ParameterVector.VECTOR_TYPE_ANY]))
+        self.addOutput(OutputVector(self.OUTPUT, 'Symetrical difference'))
+
+    def processAlgorithm(self, progress):
+        layerA = dataobjects.getObjectFromUri(
+            self.getParameterValue(self.INPUT))
+        layerB = dataobjects.getObjectFromUri(
+            self.getParameterValue(self.OVERLAY))
+
+        providerA = layerA.dataProvider()
+        providerB = layerB.dataProvider()
+
+        GEOS_EXCEPT = True
+        FEATURE_EXCEPT = True
+
+        fields = vector.combineVectorFields(layerA, layerB)
+        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
+            fields, providerA.geometryType(), providerA.crs())
+
+        featB = QgsFeature()
+        outFeat = QgsFeature()
+
+        indexA = vector.spatialindex(layerB)
+        indexB = vector.spatialindex(layerA)
+
+        featuresA = vector.features(layerA)
+        featuresB = vector.features(layerB)
+
+        total = 100.0 / (len(featuresA) * len(featuresB))
+        count = 0
+
+        for featA in featuresA:
+            add = True
+            geom = QgsGeometry(featA.geometry())
+            diffGeom = QgsGeometry(geom)
+            attrs = featA.attributes()
+            intersects = indexA.intersects(geom.boundingBox())
+            for i in intersects:
+                providerB.getFeatures(QgsFeatureRequest().setFilterFid(i)).nextFeature(featB)
+                tmpGeom = QgsGeometry(featB.geometry())
+                try:
+                    if diffGeom.intersects(tmpGeom):
+                        diffGeom = QgsGeometry(diffGeom.difference(tmpGeom))
+                except:
+                    add = False
+                    GEOS_EXCEPT = False
+                    break
+            if add:
+                try:
+                    outFeat.setGeometry(diffGeom)
+                    outFeat.setAttributes(attrs)
+                    writer.addFeature(outFeat)
+                except:
+                    FEATURE_EXCEPT = False
+                    continue
+
+            count += 1
+            progress.setPercentage(int(count * total))
+
+        length = len(providerA.fields())
+
+        for featA in featuresB:
+            add = True
+            geom = QgsGeometry(featA.geometry())
+            diffGeom = QgsGeometry(geom)
+            attrs = featA.attributes()
+            attrs = [NULL] * length + attrs
+            intersects = indexB.intersects(geom.boundingBox())
+            for i in intersects:
+                providerA.getFeatures(QgsFeatureRequest().setFilterFid(i)).nextFeature(featB)
+                tmpGeom = QgsGeometry(featB.geometry())
+                try:
+                    if diffGeom.intersects(tmpGeom):
+                        diffGeom = QgsGeometry(diffGeom.difference(tmpGeom))
+                except:
+                    add = False
+                    GEOS_EXCEPT = False
+                    break
+            if add:
+                try:
+                    outFeat.setGeometry(diffGeom)
+                    outFeat.setAttributes(attrs)
+                    writer.addFeature(outFeat)
+                except:
+                    FEATURE_EXCEPT = False
+                    continue
+
+            count += 1
+            progress.setPercentage(int(count * total))
+
+        del writer
+
+        if not GEOS_EXCEPT:
+            ProcessingLog.addToLog(
+                    ProcessingLog.LOG_WARNING,
+                    'Geometry exception while computing symetrical difference')
+        if not FEATURE_EXCEPT:
+            ProcessingLog.addToLog(
+                    ProcessingLog.LOG_WARNING,
+                    'Feature exception while computing symetrical difference')