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Added "eliminate sliver polygons" algorithm skeleton(still a draft fi…

…rst version)
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volaya committed Sep 20, 2013
1 parent 8a48b9f commit e527fe387c27f7123f3c94a1ac329e5aa3f990d3
@@ -17,6 +17,7 @@
***************************************************************************
"""
from processing.algs.Polygonize import Polygonize
from processing.algs.ftools.Eliminate import Eliminate

__author__ = 'Victor Olaya'
__date__ = 'December 2012'
@@ -112,7 +113,7 @@ def __init__(self):
ExportGeometryInfo(), Centroids(), Delaunay(), VoronoiPolygons(),
SimplifyGeometries(), DensifyGeometries(), DensifyGeometriesInterval(),
MultipartToSingleparts(), SinglePartsToMultiparts(), PolygonsToLines(),
LinesToPolygons(), ExtractNodes(),
LinesToPolygons(), ExtractNodes(),Eliminate(),
# geoprocessing
ConvexHull(), FixedDistanceBuffer(), VariableDistanceBuffer(),
Dissolve(), Difference(), Intersection(), Union(), Clip(),
@@ -0,0 +1,185 @@
# -*- coding: utf-8 -*-

"""
***************************************************************************
Eliminate.py
---------------------
Date : August 2012
Copyright : (C) 2013 by Bernhard Str�bl
Email : bernhard.stroebl@jena.de
***************************************************************************
* *
* 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. *
* *
***************************************************************************
"""
from processing.parameters.ParameterSelection import ParameterSelection
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from PyQt4 import QtCore

__author__ = 'Bernhard Strobl'
__date__ = 'August 2013'
__copyright__ = '(C) 2013, Bernhard Strobl'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'

from PyQt4.QtCore import *
from qgis.core import *
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.tools import dataobjects
from processing.parameters.ParameterVector import ParameterVector
from processing.outputs.OutputVector import OutputVector


class Eliminate(GeoAlgorithm):

INPUT = "INPUT"
OUTPUT = "OUTPUT"
MODE = "MODE"

MODES = ["Area", "Common boundary"]
MODE_AREA = 0
MODE_BOUNDARY = 1


def defineCharacteristics(self):
self.name = "Eliminate sliver polygons"
self.group = "Vector geometry tools"
self.addParameter(ParameterVector(self.INPUT, "Input layer", [ParameterVector.VECTOR_TYPE_POLYGON]))
self.addParameter(ParameterSelection(self.MODE, "Segments", self.MODES))
self.addOutput(OutputVector(self.OUTPUT, "Cleaned layer"))

def processAlgorithm(self, progress):
inLayer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT))
boundary = self.getParameterValue(self.MODE) == self.MODE_BOUNDARY

# keep references to the features to eliminate
fidsToEliminate = inLayer.selectedFeaturesIds()


provider = inLayer.dataProvider()
output = self.getOutputFromName(self.OUTPUT)
writer = output.getVectorWriter( provider.fields(),
provider.geometryType(),
inLayer.crs() )

#write all features to output layer
iterator = inLayer.getFeatures()
for feature in iterator:
writer.addFeature(feature)

#Open the layer to start cleaning it
outFileName = output.value
outLayer = QgsVectorLayer(outFileName, QtCore.QFileInfo(outFileName).completeBaseName(), "ogr")


# delete features to be eliminated in outLayer
outLayer.setSelectedFeatures(fidsToEliminate)
outLayer.startEditing()

if outLayer.deleteSelectedFeatures():
if self.saveChanges(outLayer):
outLayer.startEditing()
else:
raise GeoAlgorithmExecutionException("Could not delete features")

# ANALYZE
start = 20.00
progress.setPercentage(start)
add = 80.00 / len(fidsToEliminate)

lastLen = 0
geomsToMerge = dict()

# we go through the list and see if we find any polygons we can merge the selected with
# if we have no success with some we merge and then restart the whole story
while (lastLen != inLayer.selectedFeatureCount()): #check if we made any progress
lastLen = inLayer.selectedFeatureCount()
fidsToDeselect = []

#iterate over the polygons to eliminate
for fid2Eliminate in inLayer.selectedFeaturesIds():
feat = QgsFeature()

if inLayer.getFeatures( QgsFeatureRequest().setFilterFid( fid2Eliminate ).setSubsetOfAttributes([]) ).nextFeature( feat ):
geom2Eliminate = feat.geometry()
bbox = geom2Eliminate.boundingBox()
fit = outLayer.getFeatures( QgsFeatureRequest().setFilterRect( bbox ) )
mergeWithFid = None
mergeWithGeom = None
max = 0

selFeat = QgsFeature()
while fit.nextFeature(selFeat):
selGeom = selFeat.geometry()

if geom2Eliminate.intersects(selGeom): # we have a candidate
iGeom = geom2Eliminate.intersection(selGeom)

if boundary:
selValue = iGeom.length()
else:
# we need a common boundary
if 0 < iGeom.length():
selValue = selGeom.area()
else:
selValue = 0

if selValue > max:
max = selValue
mergeWithFid = selFeat.id()
mergeWithGeom = QgsGeometry(selGeom) # deep copy of the geometry

if mergeWithFid != None: # a successful candidate
newGeom = mergeWithGeom.combine(geom2Eliminate)

if outLayer.changeGeometry(mergeWithFid, newGeom):
# write change back to disc
if self.saveChanges(outLayer):
outLayer.startEditing()
else:
return

# mark feature as eliminated in inLayer
fidsToDeselect.append(fid2Eliminate)
else:
raise GeoAlgorithmExecutionException("Could not replace geometry of feature with id %s" % (mergeWithFid))

start = start + add
progress.setPercentage(start)
# end for fid2Eliminate

# deselect features that are already eliminated in inLayer
inLayer.deselect(fidsToDeselect)

#end while

if inLayer.selectedFeatureCount() > 0:
# copy all features that could not be eliminated to outLayer
if outLayer.addFeatures(inLayer.selectedFeatures()):
# inform user
fidList = ""

for fid in inLayer.selectedFeaturesIds():
if not fidList == "":
fidList += ", "

fidList += str(fid)

raise GeoAlgorithmExecutionException("Could not eliminate features with these ids:\n%s" % (fidList))
else:
raise GeoAlgorithmExecutionException("Could not add features")

# stop editing outLayer and commit any pending changes
self.saveChanges(outLayer)

def saveChanges(self, outLayer):
if not outLayer.commitChanges():
msg = ""
for aStrm in outLayer.commitErrors():
msg = msg + "\n" + aStrm
outLayer.rollBack()
raise GeoAlgorithmExecutionException("Commit error:\n%s" % (msg))

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