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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.
140 lines
5.2 KiB
Python
140 lines
5.2 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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PointsFromPolygons.py
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---------------------
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Date : August 2013
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Copyright : (C) 2013 by Alexander Bruy
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Email : alexander dot bruy 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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from builtins import range
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__author__ = 'Alexander Bruy'
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__date__ = 'August 2013'
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__copyright__ = '(C) 2013, Alexander Bruy'
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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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from osgeo import gdal
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from qgis.core import (QgsApplication,
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QgsFields,
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QgsField,
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QgsFeature,
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QgsFeatureSink,
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QgsGeometry,
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QgsWkbTypes,
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QgsPointXY,
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QgsProcessingUtils)
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from qgis.PyQt.QtCore import QVariant
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.core.parameters import ParameterRaster
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from processing.core.parameters import ParameterVector
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects, raster
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class PointsFromPolygons(QgisAlgorithm):
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INPUT_RASTER = 'INPUT_RASTER'
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RASTER_BAND = 'RASTER_BAND'
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INPUT_VECTOR = 'INPUT_VECTOR'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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def group(self):
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return self.tr('Vector analysis 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(ParameterRaster(self.INPUT_RASTER,
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self.tr('Raster layer')))
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self.addParameter(ParameterVector(self.INPUT_VECTOR,
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self.tr('Vector layer'), [dataobjects.TYPE_VECTOR_POLYGON]))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Points from polygons'), datatype=[dataobjects.TYPE_VECTOR_POINT]))
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def name(self):
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return 'generatepointspixelcentroidsinsidepolygons'
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def displayName(self):
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return self.tr('Generate points (pixel centroids) inside polygons')
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def processAlgorithm(self, parameters, context, feedback):
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layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_VECTOR), context)
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rasterPath = str(self.getParameterValue(self.INPUT_RASTER))
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rasterDS = gdal.Open(rasterPath, gdal.GA_ReadOnly)
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geoTransform = rasterDS.GetGeoTransform()
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rasterDS = None
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fields = QgsFields()
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fields.append(QgsField('id', QVariant.Int, '', 10, 0))
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fields.append(QgsField('poly_id', QVariant.Int, '', 10, 0))
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fields.append(QgsField('point_id', QVariant.Int, '', 10, 0))
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writer = self.getOutputFromName(self.OUTPUT_LAYER).getVectorWriter(fields, QgsWkbTypes.Point,
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layer.crs(), context)
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outFeature = QgsFeature()
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outFeature.setFields(fields)
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fid = 0
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polyId = 0
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pointId = 0
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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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geom = f.geometry()
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bbox = geom.boundingBox()
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xMin = bbox.xMinimum()
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xMax = bbox.xMaximum()
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yMin = bbox.yMinimum()
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yMax = bbox.yMaximum()
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(startRow, startColumn) = raster.mapToPixel(xMin, yMax, geoTransform)
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(endRow, endColumn) = raster.mapToPixel(xMax, yMin, geoTransform)
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# use prepared geometries for faster intersection tests
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engine = QgsGeometry.createGeometryEngine(geom.geometry())
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engine.prepareGeometry()
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for row in range(startRow, endRow + 1):
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for col in range(startColumn, endColumn + 1):
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(x, y) = raster.pixelToMap(row, col, geoTransform)
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point = QgsPointXY()
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point.setX(x)
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point.setY(y)
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if engine.contains(point):
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outFeature.setGeometry(QgsGeometry(point))
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outFeature['id'] = fid
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outFeature['poly_id'] = polyId
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outFeature['point_id'] = pointId
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fid += 1
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pointId += 1
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writer.addFeature(outFeature, QgsFeatureSink.FastInsert)
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pointId = 0
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polyId += 1
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feedback.setProgress(int(current * total))
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del writer
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