[FEATURE] Make processing dissolve algorithm accept multiple fields

nyalldawson · nyalldawson · commit 7853aa186152 · 2016-08-10T08:09:02.000+10:00
This allows you to dissolve based on more than one field value (cherry-picked from bb54b4f)
diff --git a/python/plugins/processing/algs/qgis/Dissolve.py b/python/plugins/processing/algs/qgis/Dissolve.py
@@ -26,6 +26,7 @@
 __revision__ = '$Format:%H$'
 
 import os
+from collections import defaultdict
 
 from qgis.PyQt.QtGui import QIcon
 
@@ -36,7 +37,7 @@
 from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
 from processing.core.parameters import ParameterVector
 from processing.core.parameters import ParameterBoolean
-from processing.core.parameters import ParameterTableField
+from processing.core.parameters import ParameterTableMultipleField
 from processing.core.outputs import OutputVector
 from processing.tools import vector, dataobjects
 
@@ -60,14 +61,14 @@ def defineCharacteristics(self):
                                           self.tr('Input layer'),
                                           [ParameterVector.VECTOR_TYPE_POLYGON, ParameterVector.VECTOR_TYPE_LINE]))
         self.addParameter(ParameterBoolean(Dissolve.DISSOLVE_ALL,
-                                           self.tr('Dissolve all (do not use field)'), True))
-        self.addParameter(ParameterTableField(Dissolve.FIELD,
-                                              self.tr('Unique ID field'), Dissolve.INPUT, optional=True))
+                                           self.tr('Dissolve all (do not use fields)'), True))
+        self.addParameter(ParameterTableMultipleField(Dissolve.FIELD,
+                                                      self.tr('Unique ID fields'), Dissolve.INPUT, optional=True))
         self.addOutput(OutputVector(Dissolve.OUTPUT, self.tr('Dissolved')))
 
     def processAlgorithm(self, progress):
         useField = not self.getParameterValue(Dissolve.DISSOLVE_ALL)
-        fieldname = self.getParameterValue(Dissolve.FIELD)
+        field_names = self.getParameterValue(Dissolve.FIELD)
         vlayerA = dataobjects.getObjectFromUri(
             self.getParameterValue(Dissolve.INPUT))
         fields = vlayerA.fields()
@@ -124,20 +125,16 @@ def processAlgorithm(self, progress):
             outFeat.setAttributes(attrs)
             writer.addFeature(outFeat)
         else:
-            fieldIdx = vlayerA.fieldNameIndex(fieldname)
-            unique = vector.getUniqueValues(vlayerA, int(fieldIdx))
-            nFeat = len(unique)
-            myDict = {}
-            attrDict = {}
-            for item in unique:
-                myDict[unicode(item).strip()] = []
-                attrDict[unicode(item).strip()] = None
+            field_indexes = [vlayerA.fieldNameIndex(f) for f in field_names.split(';')]
 
-            unique = None
+            attribute_dict = {}
+            geometry_dict = defaultdict(lambda: [])
 
             for inFeat in features:
                 attrs = inFeat.attributes()
-                tempItem = attrs[fieldIdx]
+
+                index_attrs = tuple([attrs[i] for i in field_indexes])
+
                 tmpInGeom = QgsGeometry(inFeat.geometry())
                 if tmpInGeom.isGeosEmpty():
                     continue
@@ -151,16 +148,17 @@ def processAlgorithm(self, progress):
                                                        'geometry: ')
                                                + error.what())
 
-                if attrDict[unicode(tempItem).strip()] is None:
+                if not index_attrs in attribute_dict:
                     # keep attributes of first feature
-                    attrDict[unicode(tempItem).strip()] = attrs
+                    attribute_dict[index_attrs] = attrs
 
-                myDict[unicode(tempItem).strip()].append(tmpInGeom)
+                geometry_dict[index_attrs].append(tmpInGeom)
 
-            features = None
+            nFeat = len(attribute_dict)
 
             nElement = 0
-            for key, value in myDict.items():
+            for key, value in geometry_dict.items():
+                outFeat = QgsFeature()
                 nElement += 1
                 progress.setPercentage(int(nElement * 100 / nFeat))
                 try:
@@ -169,7 +167,7 @@ def processAlgorithm(self, progress):
                     raise GeoAlgorithmExecutionException(
                         self.tr('Geometry exception while dissolving'))
                 outFeat.setGeometry(tmpOutGeom)
-                outFeat.setAttributes(attrDict[key])
+                outFeat.setAttributes(attribute_dict[key])
                 writer.addFeature(outFeat)
 
         del writer
diff --git a/python/plugins/processing/tests/testdata/expected/dissolve_two_fields.gml b/python/plugins/processing/tests/testdata/expected/dissolve_two_fields.gml
@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation="http://ogr.maptools.org/ dissolve_two_fields.xsd"
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-1</gml:X><gml:Y>-3</gml:Y></gml:coord>
+      <gml:coord><gml:X>9.162955854126682</gml:X><gml:Y>6.088675623800385</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+                                                                                                                              
+  <gml:featureMember>
+    <ogr:dissolve_two_fields fid="polys.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>3,2 6,1 6,-3 2,-1 -1,-1 -1,3 3,3 3,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>aa</ogr:name>
+      <ogr:intval>1</ogr:intval>
+      <ogr:floatval>44.123456</ogr:floatval>
+    </ogr:dissolve_two_fields>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:dissolve_two_fields fid="polys.1">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>6.241458733205375,-0.054510556621882 7.241458733205375,-1.054510556621882 5.241458733205375,-1.054510556621882 6.241458733205375,-0.054510556621882</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>dd</ogr:name>
+      <ogr:floatval>0</ogr:floatval>
+    </ogr:dissolve_two_fields>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:dissolve_two_fields fid="polys.2">
+      <ogr:geometryProperty><gml:MultiPolygon srsName="EPSG:4326"><gml:polygonMember><gml:Polygon><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>4.172552783109405,4.822648752399233 4.172552783109405,5.822648752399233 5.172552783109405,5.822648752399233 5.172552783109405,4.822648752399233 4.172552783109405,4.822648752399233</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></gml:polygonMember><gml:polygonMember><gml:Polygon><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>2.443378119001919,4.423608445297505 2.443378119001919,5.0 2,5 2,6 3,6 3.0,5.423608445297505 3.443378119001919,5.423608445297505 3.443378119001919,4.423608445297505 2.443378119001919,4.423608445297505</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></gml:polygonMember></gml:MultiPolygon></ogr:geometryProperty>
+      <ogr:name>bb</ogr:name>
+      <ogr:intval>1</ogr:intval>
+      <ogr:floatval>0.123</ogr:floatval>
+    </ogr:dissolve_two_fields>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:dissolve_two_fields fid="polys.3">
+      <ogr:intval>120</ogr:intval>
+      <ogr:floatval>-100291.43213</ogr:floatval>
+    </ogr:dissolve_two_fields>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:dissolve_two_fields fid="polys.8">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>2.620729366602688,5.088675623800385 2.620729366602688,6.088675623800385 3.620729366602688,6.088675623800385 3.620729366602688,5.088675623800385 2.620729366602688,5.088675623800385</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>bb</ogr:name>
+      <ogr:intval>2</ogr:intval>
+      <ogr:floatval>0.123</ogr:floatval>
+    </ogr:dissolve_two_fields>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:dissolve_two_fields fid="polys.7">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>8.162955854126682,2.738771593090211 8.162955854126682,3.738771593090211 9.162955854126682,3.738771593090211 9.162955854126682,2.738771593090211 8.162955854126682,2.738771593090211</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>cc</ogr:name>
+      <ogr:floatval>0.123</ogr:floatval>
+    </ogr:dissolve_two_fields>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml b/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
@@ -218,6 +218,19 @@ tests:
         name: expected/dissolve_field.gml
         type: vector
 
+  - algorithm: qgis:dissolve
+    name: Dissolve using two fields
+    params:
+      DISSOLVE_ALL: false
+      FIELD: intval;name
+      INPUT:
+        name: dissolve_polys.gml
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/dissolve_two_fields.gml
+        type: vector
+
   - name: Dissolve with geometries reported as valid but as invalid with isGeosValid
     algorithm: qgis:dissolve
     params:
