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[FEATURE][processing] New extract by expression algorithm
Filters an input layer by expression
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# -*- coding: utf-8 -*- | ||
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""" | ||
*************************************************************************** | ||
ExtractByExpression.py | ||
--------------------- | ||
Date : October 2016 | ||
Copyright : (C) 2016 by Nyall Dawson | ||
*************************************************************************** | ||
* * | ||
* This program is free software; you can redistribute it and/or modify * | ||
* it under the terms of the GNU General Public License as published by * | ||
* the Free Software Foundation; either version 2 of the License, or * | ||
* (at your option) any later version. * | ||
* * | ||
*************************************************************************** | ||
""" | ||
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__author__ = 'Nyall Dawson' | ||
__date__ = 'October 2016' | ||
__copyright__ = '(C) 2016, Nyall Dawson' | ||
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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 processing | ||
from qgis.core import QgsExpression, QgsVectorLayer, QgsFeatureRequest | ||
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException | ||
from processing.core.parameters import ParameterVector | ||
from processing.core.outputs import OutputVector | ||
from processing.core.GeoAlgorithm import GeoAlgorithm | ||
from processing.core.parameters import ParameterString | ||
from processing.tools import dataobjects | ||
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class ExtractByExpression(GeoAlgorithm): | ||
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INPUT = 'INPUT' | ||
EXPRESSION = 'EXPRESSION' | ||
OUTPUT = 'OUTPUT' | ||
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def defineCharacteristics(self): | ||
self.name, self.i18n_name = self.trAlgorithm('Extract by expression') | ||
self.group, self.i18n_group = self.trAlgorithm('Vector selection tools') | ||
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self.addParameter(ParameterVector(self.INPUT, | ||
self.tr('Input Layer'))) | ||
self.addParameter(ParameterString(self.EXPRESSION, | ||
self.tr("Expression"))) | ||
self.addOutput(OutputVector(self.OUTPUT, self.tr('Extracted (expression)'))) | ||
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def processAlgorithm(self, progress): | ||
layer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT)) | ||
expression_string = self.getParameterValue(self.EXPRESSION) | ||
writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(layer.fields(), layer.wkbType(), layer.crs()) | ||
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expression = QgsExpression(expression_string) | ||
if not expression.hasParserError(): | ||
req = QgsFeatureRequest().setFilterExpression(expression_string) | ||
else: | ||
raise GeoAlgorithmExecutionException(expression.parserErrorString()) | ||
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for f in layer.getFeatures(req): | ||
writer.addFeature(f) | ||
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del writer |
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<GMLFeatureClassList> | ||
<GMLFeatureClass> | ||
<Name>extract_expression</Name> | ||
<ElementPath>extract_expression</ElementPath> | ||
<!--POLYGON--> | ||
<GeometryType>3</GeometryType> | ||
<SRSName>EPSG:4326</SRSName> | ||
<DatasetSpecificInfo> | ||
<FeatureCount>2</FeatureCount> | ||
<ExtentXMin>4.00000</ExtentXMin> | ||
<ExtentXMax>10.00000</ExtentXMax> | ||
<ExtentYMin>-3.00000</ExtentYMin> | ||
<ExtentYMax>5.00000</ExtentYMax> | ||
</DatasetSpecificInfo> | ||
<PropertyDefn> | ||
<Name>name</Name> | ||
<ElementPath>name</ElementPath> | ||
<Type>String</Type> | ||
<Width>5</Width> | ||
</PropertyDefn> | ||
<PropertyDefn> | ||
<Name>intval</Name> | ||
<ElementPath>intval</ElementPath> | ||
<Type>Integer</Type> | ||
</PropertyDefn> | ||
<PropertyDefn> | ||
<Name>floatval</Name> | ||
<ElementPath>floatval</ElementPath> | ||
<Type>Integer</Type> | ||
</PropertyDefn> | ||
</GMLFeatureClass> | ||
</GMLFeatureClassList> |
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<?xml version="1.0" encoding="utf-8" ?> | ||
<ogr:FeatureCollection | ||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" | ||
xsi:schemaLocation="" | ||
xmlns:ogr="http://ogr.maptools.org/" | ||
xmlns:gml="http://www.opengis.net/gml"> | ||
<gml:boundedBy> | ||
<gml:Box> | ||
<gml:coord><gml:X>4</gml:X><gml:Y>-3</gml:Y></gml:coord> | ||
<gml:coord><gml:X>10</gml:X><gml:Y>5</gml:Y></gml:coord> | ||
</gml:Box> | ||
</gml:boundedBy> | ||
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<gml:featureMember> | ||
<ogr:extract_expression fid="polys.1"> | ||
<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5,5 6,4 4,4 5,5</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty> | ||
<ogr:name>Aaaaa</ogr:name> | ||
<ogr:intval>-33</ogr:intval> | ||
<ogr:floatval>0</ogr:floatval> | ||
</ogr:extract_expression> | ||
</gml:featureMember> | ||
<gml:featureMember> | ||
<ogr:extract_expression fid="polys.3"> | ||
<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>6,1 10,1 10,-3 6,-3 6,1</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs><gml:innerBoundaryIs><gml:LinearRing><gml:coordinates>7,0 7,-2 9,-2 9,0 7,0</gml:coordinates></gml:LinearRing></gml:innerBoundaryIs></gml:Polygon></ogr:geometryProperty> | ||
<ogr:name>ASDF</ogr:name> | ||
<ogr:intval>0</ogr:intval> | ||
</ogr:extract_expression> | ||
</gml:featureMember> | ||
</ogr:FeatureCollection> |
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