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This algorithm creates geometries which enclose the features from an input layer. Numerous enclosing geometry types are supported, including bounding boxes (envelopes), oriented rectangles, circles and convex hulls. Optionally, the features can be grouped by a field. If set, this causes the output layer to contain one feature per grouped value with a minimal geometry covering just the features with matching values.
238 lines
9.4 KiB
Python
238 lines
9.4 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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MinimumBoundingGeometry.py
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--------------------------
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Date : September 2017
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Copyright : (C) 2017 by Nyall Dawson
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Email : nyall dot dawson at gmail dot com
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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 str
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__author__ = 'Nyall Dawson'
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__date__ = 'September 2017'
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__copyright__ = '(C) 2017, Nyall Dawson'
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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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import math
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from qgis.PyQt.QtGui import QIcon
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsField,
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QgsFeatureSink,
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QgsGeometry,
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QgsWkbTypes,
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QgsFeatureRequest,
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QgsFields,
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QgsProcessingParameterFeatureSource,
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QgsProcessingParameterField,
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QgsProcessingParameterEnum,
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QgsProcessingParameterFeatureSink,
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QgsProcessing,
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QgsFeature,
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QgsVertexId,
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QgsMultiPointV2)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class MinimumBoundingGeometry(QgisAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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TYPE = 'TYPE'
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FIELD = 'FIELD'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'convex_hull.png'))
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def group(self):
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return self.tr('Vector geometry')
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def __init__(self):
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super().__init__()
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self.type_names = [self.tr('Envelope (Bounding Box)'),
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self.tr('Minimum Oriented Rectangle'),
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self.tr('Minimum Enclosing Circle'),
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self.tr('Convex Hull')]
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def initAlgorithm(self, config=None):
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self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
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self.tr('Input layer')))
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self.addParameter(QgsProcessingParameterField(self.FIELD,
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self.tr('Field (optional, set if features should be grouped by class)'),
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parentLayerParameterName=self.INPUT, optional=True))
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self.addParameter(QgsProcessingParameterEnum(self.TYPE,
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self.tr('Geometry type'), options=self.type_names))
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self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Bounding geometry'), QgsProcessing.TypeVectorPolygon))
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def name(self):
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return 'minimumboundinggeometry'
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def displayName(self):
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return self.tr('Minimum bounding geometry')
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def tags(self):
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return self.tr('bounding,box,bounds,envelope,minimum,oriented,rectangle,enclosing,circle,convex,hull,generalization').split(',')
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def processAlgorithm(self, parameters, context, feedback):
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source = self.parameterAsSource(parameters, self.INPUT, context)
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field_name = self.parameterAsString(parameters, self.FIELD, context)
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type = self.parameterAsEnum(parameters, self.TYPE, context)
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use_field = bool(field_name)
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field_index = -1
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fields = QgsFields()
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fields.append(QgsField('id', QVariant.Int, '', 20))
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if use_field:
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# keep original field type, name and parameters
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field_index = source.fields().lookupField(field_name)
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if field_index >= 0:
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fields.append(source.fields()[field_index])
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if type == 0:
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#envelope
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fields.append(QgsField('width', QVariant.Double, '', 20, 6))
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fields.append(QgsField('height', QVariant.Double, '', 20, 6))
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fields.append(QgsField('area', QVariant.Double, '', 20, 6))
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fields.append(QgsField('perimeter', QVariant.Double, '', 20, 6))
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elif type == 1:
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#oriented rect
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fields.append(QgsField('width', QVariant.Double, '', 20, 6))
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fields.append(QgsField('height', QVariant.Double, '', 20, 6))
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fields.append(QgsField('angle', QVariant.Double, '', 20, 6))
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fields.append(QgsField('area', QVariant.Double, '', 20, 6))
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fields.append(QgsField('perimeter', QVariant.Double, '', 20, 6))
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elif type == 2:
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# circle
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fields.append(QgsField('radius', QVariant.Double, '', 20, 6))
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fields.append(QgsField('area', QVariant.Double, '', 20, 6))
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elif type == 3:
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# convex hull
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fields.append(QgsField('area', QVariant.Double, '', 20, 6))
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fields.append(QgsField('perimeter', QVariant.Double, '', 20, 6))
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(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
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fields, QgsWkbTypes.Polygon, source.sourceCrs())
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if field_index >= 0:
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geometry_dict = {}
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total = 50.0 / source.featureCount() if source.featureCount() else 1
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features = source.getFeatures(QgsFeatureRequest().setSubsetOfAttributes([field_index]))
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for current, f in enumerate(features):
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if feedback.isCanceled():
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break
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if not f.hasGeometry():
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continue
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if not f.attributes()[field_index] in geometry_dict:
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geometry_dict[f.attributes()[field_index]] = [f.geometry()]
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else:
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geometry_dict[f.attributes()[field_index]].append(f.geometry())
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feedback.setProgress(int(current * total))
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current = 0
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total = 50.0 / len(geometry_dict) if geometry_dict else 1
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for group, geometries in geometry_dict.items():
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if feedback.isCanceled():
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break
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feature = self.createFeature(feedback, current, type, geometries, group)
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sink.addFeature(feature, QgsFeatureSink.FastInsert)
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geometry_dict[group] = None
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feedback.setProgress(50 + int(current * total))
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current += 1
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else:
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total = 80.0 / source.featureCount() if source.featureCount() else 1
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features = source.getFeatures(QgsFeatureRequest().setSubsetOfAttributes([]))
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geometry_queue = []
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for current, f in enumerate(features):
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if feedback.isCanceled():
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break
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if not f.hasGeometry():
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continue
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geometry_queue.append(f.geometry())
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feedback.setProgress(int(current * total))
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if not feedback.isCanceled():
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feature = self.createFeature(feedback, 0, type, geometry_queue)
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sink.addFeature(feature, QgsFeatureSink.FastInsert)
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return {self.OUTPUT: dest_id}
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def createFeature(self, feedback, feature_id, type, geometries, class_field=None):
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attrs = [feature_id]
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if class_field is not None:
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attrs.append(class_field)
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multi_point = QgsMultiPointV2()
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for g in geometries:
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if feedback.isCanceled():
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break
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vid = QgsVertexId()
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while True:
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if feedback.isCanceled():
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break
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found, point = g.geometry().nextVertex(vid)
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if found:
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multi_point.addGeometry(point)
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else:
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break
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geometry = QgsGeometry(multi_point)
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output_geometry = None
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if type == 0:
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# envelope
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rect = geometry.boundingBox()
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output_geometry = QgsGeometry.fromRect(rect)
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attrs.append(rect.width())
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attrs.append(rect.height())
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attrs.append(rect.area())
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attrs.append(rect.perimeter())
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elif type == 1:
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# oriented rect
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output_geometry, area, angle, width, height = geometry.orientedMinimumBoundingBox()
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attrs.append(width)
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attrs.append(height)
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attrs.append(angle)
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attrs.append(area)
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attrs.append(2 * width + 2 * height)
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elif type == 2:
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# circle
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output_geometry, center, radius = geometry.minimalEnclosingCircle(segments=72)
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attrs.append(radius)
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attrs.append(math.pi * radius * radius)
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elif type == 3:
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# convex hull
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output_geometry = geometry.convexHull()
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attrs.append(output_geometry.geometry().area())
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attrs.append(output_geometry.geometry().perimeter())
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f = QgsFeature()
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f.setAttributes(attrs)
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f.setGeometry(output_geometry)
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return f
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