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FieldPyculator.py
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FieldPyculator.py
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# -*- coding: utf-8 -*-
"""
***************************************************************************
FieldPyculator.py
---------------------
Date : August 2012
Copyright : (C) 2012 by Victor Olaya
Email : volayaf at gmail dot com
***************************************************************************
* *
* 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. *
* *
***************************************************************************
"""
__author__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'
import sys
from PyQt4.QtCore import *
from qgis.core import *
from sextante.core.GeoAlgorithm import GeoAlgorithm
from sextante.core.QGisLayers import QGisLayers
from sextante.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from sextante.parameters.ParameterVector import ParameterVector
from sextante.parameters.ParameterString import ParameterString
from sextante.parameters.ParameterNumber import ParameterNumber
from sextante.parameters.ParameterSelection import ParameterSelection
from sextante.outputs.OutputVector import OutputVector
class FieldsPyculator(GeoAlgorithm):
INPUT_LAYER = "INPUT_LAYER"
FIELD_NAME = "FIELD_NAME"
FIELD_TYPE = "FIELD_TYPE"
FIELD_LENGTH = "FIELD_LENGTH"
FIELD_PRECISION = "FIELD_PRECISION"
GLOBAL = "GLOBAL"
FORMULA = "FORMULA"
OUTPUT_LAYER ="OUTPUT_LAYER"
RESULT_VAR_NAME = "value"
TYPE_NAMES = ["Integer", "Float", "String"]
TYPES = [QVariant.Int, QVariant.Double, QVariant.String]
#===========================================================================
# def getIcon(self):
# return QtGui.QIcon(os.path.dirname(__file__) + "/../images/qgis.png")
#===========================================================================
def defineCharacteristics(self):
self.name = "Advanced Python field calculator"
self.group = "Vector table tools"
self.addParameter(ParameterVector(self.INPUT_LAYER, "Input layer", ParameterVector.VECTOR_TYPE_ANY, False))
self.addParameter(ParameterString(self.FIELD_NAME, "Result field name", "NewField"))
self.addParameter(ParameterSelection(self.FIELD_TYPE, "Field type", self.TYPE_NAMES))
self.addParameter(ParameterNumber(self.FIELD_LENGTH, "Field length", 1, 255, 10))
self.addParameter(ParameterNumber(self.FIELD_PRECISION, "Field precision", 0, 10, 0))
self.addParameter(ParameterString(self.GLOBAL, "Global expression", multiline = True, optional = True))
self.addParameter(ParameterString(self.FORMULA, "Formula", "value = ", multiline = True))
self.addOutput(OutputVector(self.OUTPUT_LAYER, "Output layer"))
def processAlgorithm(self, progress):
fieldName = self.getParameterValue(self.FIELD_NAME)
fieldType = self.getParameterValue(self.FIELD_TYPE)
fieldLength = self.getParameterValue(self.FIELD_LENGTH)
fieldPrecision = self.getParameterValue(self.FIELD_PRECISION)
code = self.getParameterValue(self.FORMULA)
globalExpression = self.getParameterValue(self.GLOBAL)
output = self.getOutputFromName(self.OUTPUT_LAYER)
layer = QGisLayers.getObjectFromUri(self.getParameterValue(self.INPUT_LAYER))
provider = layer.dataProvider()
fields = provider.fields()
fields.append(QgsField(fieldName, self.TYPES[fieldType], "", fieldLength, fieldPrecision))
writer = output.getVectorWriter(fields, provider.geometryType(), layer.crs())
outFeat = QgsFeature()
new_ns = {}
#run global code
if globalExpression.strip() != "":
try:
bytecode = compile(globalExpression, '<string>', 'exec')
exec bytecode in new_ns
except:
raise GeoAlgorithmExecutionException("FieldPyculator code execute error\n" +
"Global code block can't be executed!%s \n %s" %
(unicode(sys.exc_info()[0].__name__), unicode(sys.exc_info()[1])))
#replace all fields tags
fields = provider.fields()
num = 0
for field in fields:
field_name = unicode(field.name())
replval = '__attr[' + str(num) + ']'
code = code.replace("<" + field_name + ">", replval)
num += 1
#replace all special vars
code = code.replace('$id', '__id')
code = code.replace('$geom', '__geom')
need_id = code.find("__id") != -1
need_geom = code.find("__geom") != -1
need_attrs = code.find("__attr") != -1
#compile
try:
bytecode = compile(code, '<string>', 'exec')
except:
raise GeoAlgorithmExecutionException("FieldPyculator code execute error\n"+
"Field code block can't be executed! %s \n %s",
unicode(sys.exc_info()[0].__name__), unicode(sys.exc_info()[1]))
#run
features = QGisLayers.features(layer)
nFeatures = len(features)
nElement = 1
for feat in features:
progress.setPercentage(int((100 * nElement)/nFeatures))
attrs = feat.attributes()
feat_id = feat.id()
#add needed vars
if need_id:
new_ns['__id'] = feat_id
if need_geom:
geom = feat.geometry()
new_ns['__geom'] = geom
if need_attrs:
pyattrs = [a for a in attrs]
new_ns['__attr'] = pyattrs
#clear old result
if new_ns.has_key(self.RESULT_VAR_NAME):
del new_ns[self.RESULT_VAR_NAME]
#exec
exec bytecode in new_ns
#check result
if not new_ns.has_key(self.RESULT_VAR_NAME):
raise GeoAlgorithmExecutionException("FieldPyculator code execute error\n" +
"Field code block does not return '%s1' variable! Please declare this variable in your code!" %
self.RESULT_VAR_NAME)
#write feature
nElement += 1
outFeat.setGeometry( feat.geometry() )
attrs.append(new_ns[self.RESULT_VAR_NAME])
outFeat.setAttributes(attrs)
writer.addFeature(outFeat)
del writer
def checkParameterValuesBeforeExecuting(self):
##TODO check that formula is correct and fields exist
pass