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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.
113 lines
4.0 KiB
Python
113 lines
4.0 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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AlgorithmExecutor.py
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---------------------
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Date : August 2012
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Copyright : (C) 2012 by Victor Olaya
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Email : volayaf 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__ = 'Victor Olaya'
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__date__ = 'August 2012'
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__copyright__ = '(C) 2012, Victor Olaya'
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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 sys
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from qgis.PyQt.QtCore import QCoreApplication
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from qgis.core import (QgsFeature,
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QgsVectorFileWriter,
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QgsProcessingFeedback,
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QgsSettings,
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QgsProcessingUtils,
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QgsMessageLog)
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.gui.Postprocessing import handleAlgorithmResults
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from processing.tools import dataobjects
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from processing.tools.system import getTempFilename
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def execute(alg, context=None, feedback=None):
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"""Executes a given algorithm, showing its progress in the
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progress object passed along.
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Return true if everything went OK, false if the algorithm
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could not be completed.
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"""
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if feedback is None:
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feedback = QgsProcessingFeedback()
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if context is None:
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context = dataobjects.createContext()
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try:
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alg.execute(context, feedback)
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return True
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except GeoAlgorithmExecutionException as e:
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QgsMessageLog.logMessage(str(sys.exc_info()[0]), 'Processing', QgsMessageLog.CRITICAL)
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if feedback is not None:
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feedback.reportError(e.msg)
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return False
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def executeIterating(alg, paramToIter, context, feedback):
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# Generate all single-feature layers
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settings = QgsSettings()
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systemEncoding = settings.value('/UI/encoding', 'System')
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layerfile = alg.getParameterValue(paramToIter)
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layer = dataobjects.QgsProcessingUtils.mapLayerFromString(layerfile, context, False)
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feat = QgsFeature()
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filelist = []
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outputs = {}
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features = QgsProcessingUtils.getFeatures(layer, context)
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for feat in features:
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output = getTempFilename('shp')
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filelist.append(output)
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writer = QgsVectorFileWriter(output, systemEncoding,
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layer.fields(), layer.wkbType(), layer.crs())
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writer.addFeature(feat)
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del writer
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# store output values to use them later as basenames for all outputs
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for out in alg.outputs:
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outputs[out.name] = out.value
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# now run all the algorithms
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for i, f in enumerate(filelist):
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alg.setParameterValue(paramToIter, f)
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for out in alg.outputs:
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filename = outputs[out.name]
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if filename:
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filename = filename[:filename.rfind('.')] + '_' + str(i) \
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+ filename[filename.rfind('.'):]
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out.value = filename
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feedback.setProgressText(tr('Executing iteration {0}/{1}...').format(i, len(filelist)))
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feedback.setProgress(i * 100 / len(filelist))
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if execute(alg, None, feedback):
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handleAlgorithmResults(alg, context, None, False)
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else:
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return False
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return True
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def tr(string, context=''):
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if context == '':
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context = 'AlgorithmExecutor'
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return QCoreApplication.translate(context, string)
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