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06c4b07222
Since the layer has more complete knowledge of the crs (ie, when provider could not determine crs and user has selected it from the list), and also better knowledge of layer fields (virtual fields, joined fields) we should use these rather than the provider methods.
168 lines
7.0 KiB
Python
168 lines
7.0 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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FieldsCalculator.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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from qgis.PyQt.QtCore import QVariant
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from qgis.core import QgsExpression, QgsExpressionContext, QgsExpressionContextUtils, QgsFeature, QgsField, QgsDistanceArea, QgsProject, GEO_NONE
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from qgis.utils import iface
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterString
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from processing.core.parameters import ParameterNumber
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from processing.core.parameters import ParameterBoolean
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from processing.core.parameters import ParameterSelection
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects, vector, system
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from .ui.FieldsCalculatorDialog import FieldsCalculatorDialog
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class FieldsCalculator(GeoAlgorithm):
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INPUT_LAYER = 'INPUT_LAYER'
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NEW_FIELD = 'NEW_FIELD'
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FIELD_NAME = 'FIELD_NAME'
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FIELD_TYPE = 'FIELD_TYPE'
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FIELD_LENGTH = 'FIELD_LENGTH'
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FIELD_PRECISION = 'FIELD_PRECISION'
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FORMULA = 'FORMULA'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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TYPES = [QVariant.Double, QVariant.Int, QVariant.String, QVariant.Date]
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def defineCharacteristics(self):
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self.name, self.i18n_name = self.trAlgorithm('Field calculator')
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self.group, self.i18n_group = self.trAlgorithm('Vector table tools')
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self.type_names = [self.tr('Float'),
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self.tr('Integer'),
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self.tr('String'),
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self.tr('Date')]
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self.addParameter(ParameterVector(self.INPUT_LAYER,
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self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_ANY], False))
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self.addParameter(ParameterString(self.FIELD_NAME,
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self.tr('Result field name')))
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self.addParameter(ParameterSelection(self.FIELD_TYPE,
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self.tr('Field type'), self.type_names))
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self.addParameter(ParameterNumber(self.FIELD_LENGTH,
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self.tr('Field length'), 1, 255, 10))
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self.addParameter(ParameterNumber(self.FIELD_PRECISION,
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self.tr('Field precision'), 0, 15, 3))
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self.addParameter(ParameterBoolean(self.NEW_FIELD,
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self.tr('Create new field'), True))
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self.addParameter(ParameterString(self.FORMULA, self.tr('Formula')))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Calculated')))
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def processAlgorithm(self, progress):
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layer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT_LAYER))
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fieldName = self.getParameterValue(self.FIELD_NAME)
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fieldType = self.TYPES[self.getParameterValue(self.FIELD_TYPE)]
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width = self.getParameterValue(self.FIELD_LENGTH)
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precision = self.getParameterValue(self.FIELD_PRECISION)
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newField = self.getParameterValue(self.NEW_FIELD)
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formula = self.getParameterValue(self.FORMULA)
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output = self.getOutputFromName(self.OUTPUT_LAYER)
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if output.value == '':
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ext = output.getDefaultFileExtension(self)
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output.value = system.getTempFilenameInTempFolder(
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output.name + '.' + ext)
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fields = layer.fields()
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if newField:
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fields.append(QgsField(fieldName, fieldType, '', width, precision))
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writer = output.getVectorWriter(fields, layer.wkbType(),
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layer.crs())
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exp = QgsExpression(formula)
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da = QgsDistanceArea()
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da.setSourceCrs(layer.crs().srsid())
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da.setEllipsoidalMode(
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iface.mapCanvas().mapSettings().hasCrsTransformEnabled())
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da.setEllipsoid(QgsProject.instance().readEntry(
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'Measure', '/Ellipsoid', GEO_NONE)[0])
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exp.setGeomCalculator(da)
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exp.setDistanceUnits(QgsProject.instance().distanceUnits())
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exp.setAreaUnits(QgsProject.instance().areaUnits())
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exp_context = QgsExpressionContext()
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exp_context.appendScope(QgsExpressionContextUtils.globalScope())
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exp_context.appendScope(QgsExpressionContextUtils.projectScope())
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exp_context.appendScope(QgsExpressionContextUtils.layerScope(layer))
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if not exp.prepare(exp_context):
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raise GeoAlgorithmExecutionException(
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self.tr('Evaluation error: %s' % exp.evalErrorString()))
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outFeature = QgsFeature()
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outFeature.initAttributes(len(fields))
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outFeature.setFields(fields)
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error = ''
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calculationSuccess = True
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features = vector.features(layer)
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total = 100.0 / len(features)
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rownum = 1
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for current, f in enumerate(features):
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rownum = current + 1
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exp_context.setFeature(f)
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exp_context.lastScope().setVariable("row_number", rownum)
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value = exp.evaluate(exp_context)
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if exp.hasEvalError():
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calculationSuccess = False
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error = exp.evalErrorString()
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break
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else:
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outFeature.setGeometry(f.geometry())
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for fld in f.fields():
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outFeature[fld.name()] = f[fld.name()]
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outFeature[fieldName] = value
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writer.addFeature(outFeature)
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progress.setPercentage(int(current * total))
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del writer
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if not calculationSuccess:
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raise GeoAlgorithmExecutionException(
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self.tr('An error occurred while evaluating the calculation '
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'string:\n%s' % error))
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def checkParameterValuesBeforeExecuting(self):
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newField = self.getParameterValue(self.NEW_FIELD)
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fieldName = self.getParameterValue(self.FIELD_NAME).strip()
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if newField and len(fieldName) == 0:
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return self.tr('Field name is not set. Please enter a field name')
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def getCustomParametersDialog(self):
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return FieldsCalculatorDialog(self)
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