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20c07a58e6
Because - OTF reprojection is mature and stable - Should be no cost when not required - transforms are shortcut when not required - Reduces code complexity - Canvas OTF support was being incorrectly used as a flag for whether measurements should be made in ellipsoidal mode. Instead the project's ellipsoid setting should be checked for this. - Should simplify behavior for new users
159 lines
6.6 KiB
Python
159 lines
6.6 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')))
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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, feedback):
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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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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())
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da.setEllipsoidalMode(True)
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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(QgsExpressionContextUtils.globalProjectLayerScopes(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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feedback.setProgress(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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