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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
142 lines
5.2 KiB
Python
142 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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QgsGeometry,
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QgsWkbTypes,
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QgsPointV2,
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QgsProcessingUtils)
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from qgis.PyQt.QtCore import QVariant
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from processing.core.GeoAlgorithm import GeoAlgorithm
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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, vector, raster
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class PointsFromPolygons(GeoAlgorithm):
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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 icon(self):
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return QgsApplication.getThemeIcon("/providerQgis.svg")
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def svgIconPath(self):
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return QgsApplication.iconPath("providerQgis.svg")
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def group(self):
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return self.tr('Vector analysis tools')
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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 defineCharacteristics(self):
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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 processAlgorithm(self, context, feedback):
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layer = dataobjects.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.toList(), 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 / QgsProcessingUtils.featureCount(layer, context)
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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 = QgsPointV2()
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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)
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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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