[FEATURE][Processing] Minimal enclosing circle

qgis · Sep 2, 2017 · e30f704 · e30f704
1 parent f51244c
commit e30f704
Show file tree

Hide file tree

Showing 15 changed files with 595 additions and 3 deletions.
diff --git a/python/core/geometry/qgscircle.sip b/python/core/geometry/qgscircle.sip
@@ -112,6 +112,19 @@ class QgsCircle : QgsEllipse
  :rtype: QgsCircle
 %End
 
+    static QgsCircle minimalCircleFrom3Points( const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3, double epsilon = 1E-8 );
+%Docstring
+ Constructs the smallest circle from 3 points.
+ Z and m values are dropped for the center point.
+ The azimuth always takes the default value.
+ If the points are colinear an empty circle is returned.
+ \param pt1 First point.
+ \param pt2 Second point.
+ \param pt3 Third point.
+ \param epsilon Value used to compare point.
+ :rtype: QgsCircle
+%End
+
     virtual double area() const;
 
     virtual double perimeter() const;
@@ -159,6 +172,11 @@ Set the radius of the circle
  :rtype: QgsCircularString
 %End
 
+    bool contains( const QgsPoint &point, double epsilon = 1E-8 ) const;
+%Docstring
+Returns true if the circle contains the ``point``.
+ :rtype: bool
+%End
 
     virtual QgsRectangle boundingBox() const;
 

diff --git a/python/core/geometry/qgsgeometry.sip b/python/core/geometry/qgsgeometry.sip
@@ -577,6 +577,16 @@ Returns true if WKB of the geometry is of WKBMulti* type
  :rtype: QgsGeometry
 %End
 
+    QgsGeometry minimalEnclosingCircle( QgsPointXY &center /Out/, double &radius /Out/, unsigned int segments = 36 ) const;
+%Docstring
+ Returns the minimal enclosing circle for the geometry.
+ \param center Center of the minimal enclosing circle returneds
+ \param radius Radius of the minimal enclosing circle returned
+.. seealso:: QgsEllipse.toPolygon()
+.. versionadded:: 3.0
+ :rtype: QgsGeometry
+%End
+
     QgsGeometry orthogonalize( double tolerance = 1.0E-8, int maxIterations = 1000, double angleThreshold = 15.0 ) const;
 %Docstring
  Attempts to orthogonalize a line or polygon geometry by shifting vertices to make the geometries

diff --git a/python/plugins/processing/algs/help/qgis.yaml b/python/plugins/processing/algs/help/qgis.yaml
@@ -354,6 +354,11 @@ qgis:orientedminimumboundingbox: >
 
   As an alternative, the output layer can contain not just a single rectangle, but one for each input feature, representing the minimum rectangle that covers each of them.
 
+qgis:minimalenclosingcircle: >
+  This algorithm takes a vector layer and generate a new one with the minimum enclosing circle that covers all the input features.
+
+  As an alternative, the output layer can contain not just a single circle, but one for each input feature, representing the minimum enclosing circle that covers each of them.
+
 qgis:orthogonalize: >
   This algorithm takes a line or polygon layer and attempts to orthogonalize all the geometries in the layer. This process shifts the nodes in the geometries to try to make every angle in the geometry either a right angle or a straight line.
 

diff --git a/python/plugins/processing/algs/qgis/MinimalEnclosingCircle.py b/python/plugins/processing/algs/qgis/MinimalEnclosingCircle.py
@@ -0,0 +1,142 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    MinimalEnclosingCircle.py
+    ---------------------
+    Date                 : September 2017
+    Copyright            : (C) 2017, Loïc BARTOLETTI
+    Email                : lbartoletti at tuxfamily dot org
+***************************************************************************
+*                                                                         *
+*   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__ = 'Loïc BARTOLETTI'
+__date__ = 'September 2017'
+__copyright__ = '(C) 2017, Loïc BARTOLETTI'
+
+# This will get replaced with a git SHA1 when you do a git archive
+
+__revision__ = '$Format:%H$'
+
+from qgis.PyQt.QtCore import QVariant
+from qgis.core import (QgsField,
+                       QgsFields,
+                       QgsFeatureSink,
+                       QgsGeometry,
+                       QgsFeature,
+                       QgsWkbTypes,
+                       QgsFeatureRequest,
+                       QgsProcessing,
+                       QgsProcessingParameterFeatureSource,
+                       QgsProcessingParameterBoolean,
+                       QgsProcessingParameterFeatureSink,
+                       QgsProcessingException)
+from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
+
+
+class MinimalEnclosingCircle(QgisAlgorithm):
+
+    INPUT = 'INPUT'
+    BY_FEATURE = 'BY_FEATURE'
+
+    OUTPUT = 'OUTPUT'
+
+    def group(self):
+        return self.tr('Vector general')
+
+    def __init__(self):
+        super().__init__()
+
+    def initAlgorithm(self, config=None):
+        self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
+                                                              self.tr('Input layer'), [QgsProcessing.TypeVectorAnyGeometry]))
+        self.addParameter(QgsProcessingParameterBoolean(self.BY_FEATURE,
+                                                        self.tr('Calculate bounds for each feature separately'), defaultValue=True))
+
+        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Enclosing circles'), QgsProcessing.TypeVectorPolygon))
+
+    def name(self):
+        return 'minimalenclosingcircle'
+
+    def displayName(self):
+        return self.tr('Minimal enclosing circle')
+
+    def processAlgorithm(self, parameters, context, feedback):
+        source = self.parameterAsSource(parameters, self.INPUT, context)
+        by_feature = self.parameterAsBool(parameters, self.BY_FEATURE, context)
+
+        if not by_feature and QgsWkbTypes.geometryType(source.wkbType()) == QgsWkbTypes.PointGeometry and source.featureCount() <= 2:
+            raise QgsProcessingException(self.tr("Can't calculate a minimal enclosing circle for each point, it's a point. The number of points must be greater than 2"))
+
+        if by_feature:
+            fields = source.fields()
+        else:
+            fields = QgsFields()
+        fields.append(QgsField('center_x', QVariant.Double))
+        fields.append(QgsField('center_y', QVariant.Double))
+        fields.append(QgsField('radius', QVariant.Double))
+
+        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
+                                               fields, QgsWkbTypes.Polygon, source.sourceCrs())
+
+        if by_feature:
+            self.featureMec(source, context, sink, feedback)
+        else:
+            self.layerMec(source, context, sink, feedback)
+
+        return {self.OUTPUT: dest_id}
+
+    def layerMec(self, source, context, sink, feedback):
+        req = QgsFeatureRequest().setSubsetOfAttributes([])
+        features = source.getFeatures(req)
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
+        newgeometry = QgsGeometry()
+        first = True
+        geometries = []
+        for current, inFeat in enumerate(features):
+            if feedback.isCanceled():
+                break
+
+            if inFeat.hasGeometry():
+                geometries.append(inFeat.geometry())
+            feedback.setProgress(int(current * total))
+
+        newgeometry = QgsGeometry.unaryUnion(geometries)
+        geometry, center, radius = newgeometry.minimalEnclosingCircle()
+
+        if geometry:
+            outFeat = QgsFeature()
+
+            outFeat.setGeometry(geometry)
+            outFeat.setAttributes([center.x(),
+                                   center.y(),
+                                   radius])
+            sink.addFeature(outFeat, QgsFeatureSink.FastInsert)
+
+    def featureMec(self, source, context, sink, feedback):
+        features = source.getFeatures()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
+        outFeat = QgsFeature()
+        for current, inFeat in enumerate(features):
+            if feedback.isCanceled():
+                break
+
+            geometry, center, radius = inFeat.geometry().minimalEnclosingCircle()
+            if geometry:
+                outFeat.setGeometry(geometry)
+                attrs = inFeat.attributes()
+                attrs.extend([center.x(),
+                              center.y(),
+                              radius])
+                outFeat.setAttributes(attrs)
+                sink.addFeature(outFeat, QgsFeatureSink.FastInsert)
+            else:
+                feedback.pushInfo(self.tr("Can't calculate a minimal enclosing circle for feature {0}.").format(inFeat.id()))
+            feedback.setProgress(int(current * total))
diff --git a/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py b/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py
@@ -100,6 +100,7 @@
 from .MeanCoords import MeanCoords
 from .Merge import Merge
 from .MergeLines import MergeLines
+from .MinimalEnclosingCircle import MinimalEnclosingCircle
 from .NearestNeighbourAnalysis import NearestNeighbourAnalysis
 from .OffsetLine import OffsetLine
 from .OrientedMinimumBoundingBox import OrientedMinimumBoundingBox
@@ -253,6 +254,7 @@ def getAlgs(self):
                 MeanCoords(),
                 Merge(),
                 MergeLines(),
+                MinimalEnclosingCircle(),
                 NearestNeighbourAnalysis(),
                 OffsetLine(),
                 OrientedMinimumBoundingBox(),

diff --git a/python/plugins/processing/tests/testdata/expected/enclosing_circles_all.gfs b/python/plugins/processing/tests/testdata/expected/enclosing_circles_all.gfs
@@ -0,0 +1,31 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>enclosing_circles_all</Name>
+    <ElementPath>enclosing_circles_all</ElementPath>
+    <!--POLYGON-->
+    <GeometryType>3</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>1</FeatureCount>
+      <ExtentXMin>-1.50891</ExtentXMin>
+      <ExtentXMax>10.30638</ExtentXMax>
+      <ExtentYMin>-5.30638</ExtentYMin>
+      <ExtentYMax>6.50891</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>center_x</Name>
+      <ElementPath>center_x</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>center_y</Name>
+      <ElementPath>center_y</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>radius</Name>
+      <ElementPath>radius</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/enclosing_circles_all.gml b/python/plugins/processing/tests/testdata/expected/enclosing_circles_all.gml
@@ -0,0 +1,22 @@
+<?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>-1.508909716010908</gml:X><gml:Y>-5.306378070441288</gml:Y></gml:coord>
+      <gml:coord><gml:X>10.30637807044129</gml:X><gml:Y>6.508909716010908</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:enclosing_circles_all fid="enclosing_circles_all.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>4.39873417721519,6.50890971601091 5.42458577357907,6.4191593308691 6.41926738829339,6.15263519548031 7.35255612382824,5.71743551083061 8.19609447422128,5.12678359911643 8.92425195354681,4.39862611979089 9.51490386526099,3.55508776939786 9.95010354991069,2.62179903386301 10.2166276852995,1.62711741914869 10.3063780704413,0.601265822784808 10.2166276852995,-0.424585773579072 9.95010354991069,-1.41926738829339 9.51490386526099,-2.35255612382824 8.92425195354681,-3.19609447422128 8.19609447422127,-3.92425195354681 7.35255612382824,-4.514903865261 6.41926738829339,-4.95010354991069 5.42458577357907,-5.21662768529948 4.39873417721519,-5.30637807044129 3.37288258085131,-5.21662768529948 2.37820096613699,-4.95010354991069 1.44491223060214,-4.51490386526099 0.601373880209104,-3.92425195354681 -0.126783599116428,-3.19609447422127 -0.717435510830614,-2.35255612382824 -1.15263519548031,-1.41926738829339 -1.4191593308691,-0.42458577357907 -1.50890971601091,0.60126582278481 -1.4191593308691,1.62711741914869 -1.15263519548031,2.62179903386301 -0.717435510830614,3.55508776939786 -0.126783599116427,4.3986261197909 0.601373880209104,5.12678359911643 1.44491223060214,5.71743551083061 2.37820096613699,6.15263519548031 3.37288258085131,6.4191593308691 4.39873417721519,6.50890971601091</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:center_x>4.39873417721519</ogr:center_x>
+      <ogr:center_y>0.60126582278481</ogr:center_y>
+      <ogr:radius>5.9076438932261</ogr:radius>
+    </ogr:enclosing_circles_all>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/enclosing_circles_each.gfs b/python/plugins/processing/tests/testdata/expected/enclosing_circles_each.gfs
@@ -0,0 +1,47 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>enclosing_circles_each</Name>
+    <ElementPath>enclosing_circles_each</ElementPath>
+    <!--POLYGON-->
+    <GeometryType>3</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>6</FeatureCount>
+      <ExtentXMin>-1.81766</ExtentXMin>
+      <ExtentXMax>10.59982</ExtentXMax>
+      <ExtentYMin>-3.43247</ExtentYMin>
+      <ExtentYMax>6.32190</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>intval</Name>
+      <ElementPath>intval</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>floatval</Name>
+      <ElementPath>floatval</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>center_x</Name>
+      <ElementPath>center_x</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>center_y</Name>
+      <ElementPath>center_y</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>radius</Name>
+      <ElementPath>radius</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>name</Name>
+      <ElementPath>name</ElementPath>
+      <Type>String</Type>
+      <Width>5</Width>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>