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1e13d733c2
initAlgorithm() method This allows 2 benefits: - algorithms can be subclassed and have subclasses add additional parameters/outputs to the algorithm. With the previous approach of declaring parameters/outputs in the constructor, it's not possible to call virtual methods to add additional parameters/ outputs (since you can't call virtual methods from a constructor). - initAlgorithm takes a variant map argument, allowing the algorithm to dynamically adjust its declared parameters and outputs according to this configuration map. This potentially allows model algorithms which can be configured to have variable numbers of parameters and outputs at run time. E.g. a "router" algorithm which directs features to one of any number of output sinks depending on some user configured criteria.
130 lines
4.9 KiB
Python
130 lines
4.9 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ExtractSpecificNodes.py
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--------------------
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Date : October 2016
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Copyright : (C) 2016 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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__author__ = 'Nyall Dawson'
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__date__ = 'October 2016'
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__copyright__ = '(C) 2016, Nyall Dawson'
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# This will get replaced with a git SHA1 when you do a git archive323
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__revision__ = '$Format:%H$'
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import math
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import ParameterVector, ParameterString
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects
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from qgis.core import (QgsWkbTypes,
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QgsFeature,
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QgsFeatureSink,
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QgsGeometry,
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QgsField,
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QgsApplication,
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QgsProcessingUtils)
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from qgis.PyQt.QtCore import QVariant
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class ExtractSpecificNodes(QgisAlgorithm):
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INPUT_LAYER = 'INPUT_LAYER'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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NODES = 'NODES'
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def group(self):
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return self.tr('Vector geometry tools')
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def __init__(self):
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super().__init__()
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def initAlgorithm(self, config=None):
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self.addParameter(ParameterVector(self.INPUT_LAYER,
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self.tr('Input layer'), [dataobjects.TYPE_VECTOR_ANY]))
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self.addParameter(ParameterString(self.NODES,
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self.tr('Node indices'), default='0'))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Nodes'), datatype=[dataobjects.TYPE_VECTOR_POINT]))
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def name(self):
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return 'extractspecificnodes'
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def displayName(self):
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return self.tr('Extract specific nodes')
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def processAlgorithm(self, parameters, context, feedback):
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layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_LAYER), context)
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fields = layer.fields()
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fields.append(QgsField('node_pos', QVariant.Int))
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fields.append(QgsField('node_index', QVariant.Int))
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fields.append(QgsField('distance', QVariant.Double))
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fields.append(QgsField('angle', QVariant.Double))
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writer = self.getOutputFromName(
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self.OUTPUT_LAYER).getVectorWriter(fields, QgsWkbTypes.Point, layer.crs(), context)
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node_indices_string = self.getParameterValue(self.NODES)
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indices = []
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for node in node_indices_string.split(','):
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try:
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indices.append(int(node))
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except:
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raise GeoAlgorithmExecutionException(
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self.tr('\'{}\' is not a valid node index').format(node))
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features = QgsProcessingUtils.getFeatures(layer, context)
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total = 100.0 / layer.featureCount() if layer.featureCount() else 0
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for current, f in enumerate(features):
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input_geometry = f.geometry()
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if not input_geometry:
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writer.addFeature(f, QgsFeatureSink.FastInsert)
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else:
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total_nodes = input_geometry.geometry().nCoordinates()
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for node in indices:
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if node < 0:
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node_index = total_nodes + node
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else:
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node_index = node
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if node_index < 0 or node_index >= total_nodes:
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continue
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distance = input_geometry.distanceToVertex(node_index)
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angle = math.degrees(input_geometry.angleAtVertex(node_index))
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output_feature = QgsFeature()
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attrs = f.attributes()
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attrs.append(node)
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attrs.append(node_index)
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attrs.append(distance)
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attrs.append(angle)
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output_feature.setAttributes(attrs)
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point = input_geometry.vertexAt(node_index)
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output_feature.setGeometry(QgsGeometry.fromPoint(point))
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writer.addFeature(output_feature, QgsFeatureSink.FastInsert)
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feedback.setProgress(int(current * total))
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del writer
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