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a05d941e4e
Since the underlying issues with the Python bindings are now fixed, in most cases we can safely default to allowing an algorithm to run in a background thread!! So now we make this the default, and require individual algorithms which are NOT thread safe to declare this. This includes algorithms which directly manipulate the current project or layers (such as setting layer styles), alter the selections in layers, or which rely on 3rd party libraries (for now, SAGA and GRASS algorithms are marked as not thread safe... TODO - someone more familiar with these libraries can investigate and remove the flag if appropriate). Also models are marked as non-thread safe. TODO: only flag an individual model as thread-unsafe if any of its child algorithms report this flag.
111 lines
4.2 KiB
Python
111 lines
4.2 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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RandomSelection.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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__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 os
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import random
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import (QgsFeatureSink,
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QgsProcessingException,
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QgsProcessingUtils,
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QgsProcessingAlgorithm,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterEnum,
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QgsProcessingParameterNumber,
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QgsProcessingParameterFeatureSink,
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QgsProcessingOutputVectorLayer)
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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 RandomSelection(QgisAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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METHOD = 'METHOD'
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NUMBER = 'NUMBER'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'random_selection.png'))
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def group(self):
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return self.tr('Vector selection')
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def groupId(self):
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return 'vectorselection'
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def flags(self):
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return super().flags() | QgsProcessingAlgorithm.FlagNoThreading
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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.methods = [self.tr('Number of selected features'),
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self.tr('Percentage of selected features')]
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self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT,
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self.tr('Input layer')))
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self.addParameter(QgsProcessingParameterEnum(self.METHOD,
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self.tr('Method'), self.methods, False, 0))
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self.addParameter(QgsProcessingParameterNumber(self.NUMBER,
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self.tr('Number/percentage of selected features'), QgsProcessingParameterNumber.Integer,
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10, False, 0.0, 999999999999.0))
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self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Selected (random)')))
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def name(self):
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return 'randomselection'
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def displayName(self):
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return self.tr('Random selection')
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def processAlgorithm(self, parameters, context, feedback):
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layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
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method = self.parameterAsEnum(parameters, self.METHOD, context)
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featureCount = layer.featureCount()
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value = self.parameterAsInt(parameters, self.NUMBER, context)
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if method == 0:
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if value > featureCount:
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raise QgsProcessingException(
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self.tr('Selected number is greater than feature count. '
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'Choose a lower value and try again.'))
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else:
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if value > 100:
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raise QgsProcessingException(
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self.tr("Percentage can't be greater than 100. Set a "
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"different value and try again."))
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value = int(round(value / 100.0, 4) * featureCount)
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selran = random.sample(list(range(featureCount)), value)
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layer.selectByIds(selran)
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return {self.OUTPUT: parameters[self.INPUT]}
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