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ConvexHull.py
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ConvexHull.py
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# -*- coding: utf-8 -*-
"""
***************************************************************************
ConvexHull.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__ = '$Format:%H$'
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from qgis.core import *
from sextante.core.GeoAlgorithm import GeoAlgorithm
from sextante.core.QGisLayers import QGisLayers
from sextante.core.SextanteLog import SextanteLog
from sextante.parameters.ParameterVector import ParameterVector
from sextante.parameters.ParameterTableField import ParameterTableField
from sextante.parameters.ParameterSelection import ParameterSelection
from sextante.outputs.OutputVector import OutputVector
from sextante.algs.ftools import FToolsUtils as utils
class ConvexHull(GeoAlgorithm):
INPUT = "INPUT"
OUTPUT = "OUTPUT"
FIELD = "FIELD"
METHOD = "METHOD"
METHODS = ["Create single minimum convex hull",
"Create convex hulls based on field"
]
#===========================================================================
# def getIcon(self):
# return QtGui.QIcon(os.path.dirname(__file__) + "/icons/convex_hull.png")
#===========================================================================
def defineCharacteristics(self):
self.name = "Convex hull"
self.group = "Vector geometry tools"
self.addParameter(ParameterVector(ConvexHull.INPUT, "Input layer", ParameterVector.VECTOR_TYPE_ANY))
self.addParameter(ParameterTableField(ConvexHull.FIELD, "Field (optional, only used if creating convex hulls by classes)", ConvexHull.INPUT, optional = True))
self.addParameter(ParameterSelection(ConvexHull.METHOD, "Method", ConvexHull.METHODS))
self.addOutput(OutputVector(ConvexHull.OUTPUT, "Convex hull"))
def processAlgorithm(self, progress):
useField = (self.getParameterValue(ConvexHull.METHOD) == 1)
fieldName = self.getParameterValue(ConvexHull.FIELD)
layer = QGisLayers.getObjectFromUri(self.getParameterValue(ConvexHull.INPUT))
GEOS_EXCEPT = True
FEATURE_EXCEPT = True
f = QgsField("value")
f.setType(QVariant.String)
f.setLength(255)
if useField:
index = layer.fieldNameIndex(fieldName)
fType = layer.pendingFields()[index].type()
if fType == QVariant.Int:
f.setType(QVariant.Int)
f.setLength(20)
elif fType == QVariant.Double:
f.setType(QVariant.Double)
f.setLength(20)
f.setPrecision(6)
else:
f.setType(QVariant.String)
f.setLength(255)
fields = [QgsField("id", QVariant.Int, "", 20),
f,
QgsField("area", QVariant.Double, "", 20, 6),
QgsField("perim", QVariant.Double, "", 20, 6)
]
writer = self.getOutputFromName(ConvexHull.OUTPUT).getVectorWriter(fields, QGis.WKBPolygon, layer.dataProvider().crs())
outFeat = QgsFeature()
inGeom = QgsGeometry()
outGeom = QgsGeometry()
current = 0
fid = 0
val = ""
if useField:
unique = layer.uniqueValues(index)
total = 100.0 / float(layer.featureCount() * len (unique))
for i in unique:
hull = []
first = True
features = QGisLayers.features(layer)
for f in features:
idVar = f[fieldName]
if idVar.toString().trimmed() == i.toString().trimmed():
if first:
val = idVar
first = False
inGeom = QgsGeometry(f.geometry())
points = utils.extractPoints(inGeom)
hull.extend(points)
current += 1
progress.setPercentage(int(current * total))
if len(hull) >= 3:
tmpGeom = QgsGeometry(outGeom.fromMultiPoint(hull))
try:
outGeom = tmpGeom.convexHull()
(area, perim) = utils.simpleMeasure(outGeom)
outFeat.setGeometry(outGeom)
outFeat.setAttributes([QVariant(fid),
QVariant(val),
QVariant(area),
QVariant(perim)
])
writer.addFeature(outFeat)
except:
GEOS_EXCEPT = False
continue
fid += 1
else:
hull = []
total = 100.0 / float(layer.featureCount())
features = QGisLayers.features(layer)
for f in features:
inGeom = QgsGeometry(f.geometry())
points = utils.extractPoints(inGeom)
hull.extend(points)
current += 1
progress.setPercentage(int(current * total))
tmpGeom = QgsGeometry(outGeom.fromMultiPoint(hull))
try:
outGeom = tmpGeom.convexHull()
(area, perim) = utils.simpleMeasure(outGeom)
outFeat.setGeometry(outGeom)
outFeat.setAttributes([QVariant(0),
QVariant("all"),
QVariant(area),
QVariant(perim)
])
writer.addFeature(outFeat)
except:
GEOS_EXCEPT = False
del writer
if not GEOS_EXCEPT:
SextanteLog.addToLog(SextanteLog.LOG_WARNING, "Geometry exception while computing convex hull")
if not FEATURE_EXCEPT:
SextanteLog.addToLog(SextanteLog.LOG_WARNING, "Feature exception while computing convex hull")