[processing] Rework centroid algorithm to handle non-polygon layers

The existing polygoncentroids algorithm has been deprecated (and hidden from the toolbox), and a new, generic centroids algorithm added which works with lines and multipoints
qgis · Aug 11, 2016 · e9423dc · e9423dc
1 parent d0faca1
commit e9423dc
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Showing 18 changed files with 595 additions and 23 deletions.
diff --git a/python/plugins/processing/algs/help/qgis.yaml b/python/plugins/processing/algs/help/qgis.yaml
@@ -44,6 +44,11 @@ qgis:buildvirtualvector: >
 
   The output virtual layer will not be open in the current project.
 
+qgis:centroids: >
+  This algorithm creates a new point layer, with points representing the centroid of the geometries in an input layer.
+
+  The attributes associated to each point in the output layer are the same ones associated to the original features.
+
 qgis:checkvalidity:
   This algorithm performs a validity check on the geometries of a vector layer.
 
@@ -306,6 +311,8 @@ qgis:polygoncentroids: >
 
   The attributes associated to each point in the output layer are the same ones associated to the original polygon.
 
+  NOTE: This algorithm is deprecated and the generic "centroids" algorithm (which works for line and multi geometry layers) should be used instead.
+
 
 qgis:polygonfromlayerextent: >
   This algorithm takes a vector layer and generate a new one with the minimum bounding box (rectangle with N-S orientation) that covers all the input features.

diff --git a/python/plugins/processing/algs/qgis/Centroids.py b/python/plugins/processing/algs/qgis/Centroids.py
@@ -29,10 +29,10 @@
 
 from qgis.PyQt.QtGui import QIcon
 
-from qgis.core import Qgis, QgsGeometry, QgsFeature, QgsWkbTypes
+from qgis.core import QgsWkbTypes
 
 from processing.core.GeoAlgorithm import GeoAlgorithm
-from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
+from processing.core.ProcessingLog import ProcessingLog
 from processing.core.parameters import ParameterVector
 from processing.core.outputs import OutputVector
 from processing.tools import dataobjects, vector
@@ -49,11 +49,11 @@ def getIcon(self):
         return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'centroids.png'))
 
     def defineCharacteristics(self):
-        self.name, self.i18n_name = self.trAlgorithm('Polygon centroids')
+        self.name, self.i18n_name = self.trAlgorithm('Centroids')
         self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
 
         self.addParameter(ParameterVector(self.INPUT_LAYER,
-                                          self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_POLYGON]))
+                                          self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_ANY]))
 
         self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Centroids')))
 
@@ -67,25 +67,18 @@ def processAlgorithm(self, progress):
                 QgsWkbTypes.Point,
                 layer.crs())
 
-        outFeat = QgsFeature()
-
         features = vector.features(layer)
         total = 100.0 / len(features)
-        for current, feat in enumerate(features):
-            inGeom = feat.geometry()
-            attrs = feat.attributes()
-
-            if inGeom.isEmpty():
-                outGeom = QgsGeometry(None)
-            else:
-                outGeom = QgsGeometry(inGeom.centroid())
-                if not outGeom:
-                    raise GeoAlgorithmExecutionException(
-                        self.tr('Error calculating centroid'))
-
-            outFeat.setGeometry(outGeom)
-            outFeat.setAttributes(attrs)
-            writer.addFeature(outFeat)
+        for current, input_feature in enumerate(features):
+            output_feature = input_feature
+            if input_feature.geometry():
+                output_geometry = input_feature.geometry().centroid()
+                if not output_geometry:
+                    ProcessingLog.addToLog(ProcessingLog.LOG_WARNING,
+                                           'Error calculating centroid for feature {}'.format(input_feature.id()))
+                output_feature.setGeometry(output_geometry)
+
+            writer.addFeature(output_feature)
             progress.setPercentage(int(current * total))
 
         del writer
diff --git a/python/plugins/processing/algs/qgis/PolygonCentroids.py b/python/plugins/processing/algs/qgis/PolygonCentroids.py
@@ -0,0 +1,96 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    PolygonCentroids.py
+    ---------------------
+    Date                 : August 2012
+    Copyright            : (C) 2012 by Victor Olaya
+    Email                : volayaf 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__ = 'Victor Olaya'
+__date__ = 'August 2012'
+__copyright__ = '(C) 2012, Victor Olaya'
+
+# This will get replaced with a git SHA1 when you do a git archive323
+
+__revision__ = '$Format:%H$'
+
+import os
+
+from qgis.PyQt.QtGui import QIcon
+
+from qgis.core import Qgis, QgsGeometry, QgsFeature, QgsWkbTypes
+
+from processing.core.GeoAlgorithm import GeoAlgorithm
+from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
+from processing.core.parameters import ParameterVector
+from processing.core.outputs import OutputVector
+from processing.tools import dataobjects, vector
+
+pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
+
+
+class PolygonCentroids(GeoAlgorithm):
+
+    INPUT_LAYER = 'INPUT_LAYER'
+    OUTPUT_LAYER = 'OUTPUT_LAYER'
+
+    def __init__(self):
+        GeoAlgorithm.__init__(self)
+        # this algorithm is deprecated - use Centroids instead
+        self.showInToolbox = False
+
+    def getIcon(self):
+        return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'centroids.png'))
+
+    def defineCharacteristics(self):
+        self.name, self.i18n_name = self.trAlgorithm('Polygon centroids')
+        self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
+
+        self.addParameter(ParameterVector(self.INPUT_LAYER,
+                                          self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_POLYGON]))
+
+        self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Centroids')))
+
+    def processAlgorithm(self, progress):
+        layer = dataobjects.getObjectFromUri(
+            self.getParameterValue(self.INPUT_LAYER))
+
+        writer = self.getOutputFromName(
+            self.OUTPUT_LAYER).getVectorWriter(
+                layer.fields(),
+                QgsWkbTypes.Point,
+                layer.crs())
+
+        outFeat = QgsFeature()
+
+        features = vector.features(layer)
+        total = 100.0 / len(features)
+        for current, feat in enumerate(features):
+            inGeom = feat.geometry()
+            attrs = feat.attributes()
+
+            if inGeom.isEmpty():
+                outGeom = QgsGeometry(None)
+            else:
+                outGeom = QgsGeometry(inGeom.centroid())
+                if not outGeom:
+                    raise GeoAlgorithmExecutionException(
+                        self.tr('Error calculating centroid'))
+
+            outFeat.setGeometry(outGeom)
+            outFeat.setAttributes(attrs)
+            writer.addFeature(outFeat)
+            progress.setPercentage(int(current * total))
+
+        del writer
diff --git a/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py b/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py
@@ -151,6 +151,7 @@
 from .Boundary import Boundary
 from .PointOnSurface import PointOnSurface
 from .OffsetLine import OffsetLine
+from .PolygonCentroids import PolygonCentroids
 
 pluginPath = os.path.normpath(os.path.join(
     os.path.split(os.path.dirname(__file__))[0], os.pardir))
@@ -204,7 +205,7 @@ def __init__(self):
                         RectanglesOvalsDiamondsVariable(),
                         RectanglesOvalsDiamondsFixed(), MergeLines(),
                         BoundingBox(), Boundary(), PointOnSurface(),
-                        OffsetLine()
+                        OffsetLine(), PolygonCentroids()
                         ]
 
         if hasMatplotlib:

diff --git a/python/plugins/processing/gui/menus.py b/python/plugins/processing/gui/menus.py
@@ -52,7 +52,7 @@
 geometryToolsMenu = vectorMenu + "/" + Processing.tr('G&eometry Tools')
 defaultMenuEntries.update({'qgis:checkvalidity': geometryToolsMenu,
                            'qgis:exportaddgeometrycolumns': geometryToolsMenu,
-                           'qgis:polygoncentroids': geometryToolsMenu,
+                           'qgis:centroids': geometryToolsMenu,
                            'qgis:delaunaytriangulation': geometryToolsMenu,
                            'qgis:voronoipolygons': geometryToolsMenu,
                            'qgis:simplifygeometries': geometryToolsMenu,

diff --git a/python/plugins/processing/tests/testdata/expected/centroid_lines.gfs b/python/plugins/processing/tests/testdata/expected/centroid_lines.gfs
@@ -0,0 +1,15 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>centroid_lines</Name>
+    <ElementPath>centroid_lines</ElementPath>
+    <GeometryType>1</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>7</FeatureCount>
+      <ExtentXMin>0.00000</ExtentXMin>
+      <ExtentXMax>8.75520</ExtentXMax>
+      <ExtentYMin>-3.00000</ExtentYMin>
+      <ExtentYMax>2.90165</ExtentYMax>
+    </DatasetSpecificInfo>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/centroid_lines.gml b/python/plugins/processing/tests/testdata/expected/centroid_lines.gml
@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>0</gml:X><gml:Y>-3</gml:Y></gml:coord>
+      <gml:coord><gml:X>8.755203820042828</gml:X><gml:Y>2.901650429449553</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.0">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>8.755203820042828,2.901650429449553</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.1">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>0,-1</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.2">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>2.375,1.625</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.3">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>4,1</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.4">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>8.5,-3.0</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.5">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>8,-1</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_lines fid="lines.6">
+    </ogr:centroid_lines>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/centroid_multilines.gfs b/python/plugins/processing/tests/testdata/expected/centroid_multilines.gfs
@@ -0,0 +1,15 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>centroid_multilines</Name>
+    <ElementPath>centroid_multilines</ElementPath>
+    <GeometryType>1</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>4</FeatureCount>
+      <ExtentXMin>0.00000</ExtentXMin>
+      <ExtentXMax>4.41936</ExtentXMax>
+      <ExtentYMin>-1.00000</ExtentYMin>
+      <ExtentYMax>2.68756</ExtentYMax>
+    </DatasetSpecificInfo>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/centroid_multilines.gml b/python/plugins/processing/tests/testdata/expected/centroid_multilines.gml
@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>0</gml:X><gml:Y>-1</gml:Y></gml:coord>
+      <gml:coord><gml:X>4.41935638121706</gml:X><gml:Y>2.687560818469874</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:centroid_multilines fid="lines.1">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>0,-1</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_multilines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multilines fid="lines.2">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>4.41935638121706,1.293104104489945</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_multilines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multilines fid="lines.3">
+    </ogr:centroid_multilines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multilines fid="lines.4">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>3.423678244400056,2.687560818469874</gml:coordinates></gml:Point></ogr:geometryProperty>
+    </ogr:centroid_multilines>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/centroid_multipoint.gfs b/python/plugins/processing/tests/testdata/expected/centroid_multipoint.gfs
@@ -0,0 +1,19 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>centroid_multipoint</Name>
+    <ElementPath>centroid_multipoint</ElementPath>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>5</FeatureCount>
+      <ExtentXMin>2.00000</ExtentXMin>
+      <ExtentXMax>4.50000</ExtentXMax>
+      <ExtentYMin>-3.00000</ExtentYMin>
+      <ExtentYMax>2.00000</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>d</Name>
+      <ElementPath>d</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/centroid_multipoint.gml b/python/plugins/processing/tests/testdata/expected/centroid_multipoint.gml
@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>2</gml:X><gml:Y>-3</gml:Y></gml:coord>
+      <gml:coord><gml:X>4.5</gml:X><gml:Y>2</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:centroid_multipoint fid="points.9">
+      <ogr:d>5</ogr:d>
+    </ogr:centroid_multipoint>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multipoint fid="points.0">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>2,2</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:d>1</ogr:d>
+    </ogr:centroid_multipoint>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multipoint fid="points.3">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>4.5,1.5</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:d>2</ogr:d>
+    </ogr:centroid_multipoint>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multipoint fid="points.5">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>4,-3</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:d>3</ogr:d>
+    </ogr:centroid_multipoint>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:centroid_multipoint fid="points.7">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>3.5,-1.0</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:d>4</ogr:d>
+    </ogr:centroid_multipoint>
+  </gml:featureMember>
+</ogr:FeatureCollection>