QGIS/python/plugins/sextante/ftools/RandomSelectionWithinSubsets.py

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from sextante.core.GeoAlgorithm import GeoAlgorithm
import os.path
from PyQt4 import QtGui
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from qgis.core import *
from sextante.parameters.ParameterVector import ParameterVector
from sextante.core.QGisLayers import QGisLayers
from sextante.outputs.OutputVector import OutputVector
from sextante.parameters.ParameterSelection import ParameterSelection
from sextante.parameters.ParameterNumber import ParameterNumber
import random
from sextante.parameters.ParameterTableField import ParameterTableField
from sextante.ftools import ftools_utils
class RandomSelectionWithinSubsets(GeoAlgorithm):
INPUT = "INPUT"
OUTPUT = "OUTPUT"
METHOD = "METHOD"
NUMBER = "NUMBER"
PERCENTAGE = "PERCENTAGE"
FIELD = "FIELD"
def getIcon(self):
return QtGui.QIcon(os.path.dirname(__file__) + "/icons/random_selection.png")
def processAlgorithm(self, progress):
method = self.getParameterValue(self.METHOD)
field = self.getParameterValue(RandomSelectionWithinSubsets.FIELD)
filename = self.getParameterValue(RandomSelectionWithinSubsets.INPUT)
vlayer = QGisLayers.getObjectFromUri(filename)
vlayer.removeSelection(True)
vprovider = vlayer.dataProvider()
allAttrs = vprovider.attributeIndexes()
vprovider.select(allAttrs)
index = vprovider.fieldNameIndex(field)
unique = ftools_utils.getUniqueValues(vprovider, int(index))
inFeat = QgsFeature()
selran = []
nFeat = vprovider.featureCount() * len(unique)
nElement = 0
if not len(unique) == vlayer.featureCount():
for i in unique:
vprovider.rewind()
FIDs= []
while vprovider.nextFeature(inFeat):
atMap = inFeat.attributeMap()
if atMap[index] == QVariant(i):
FID = inFeat.id()
FIDs.append(FID)
nElement += 1
progress.setPercentage(nElement/nFeat * 100)
if method == 0:
value = int(self.getParameterValue(self.NUMBER))
else:
value = self.getParameterValue(self.PERCENTAGE)
value = int(round((value / 100.0000) * len(FIDs), 0))
if value >= len(FIDs):
selFeat = FIDs
else:
selFeat = random.sample(FIDs, value)
selran.extend(selFeat)
vlayer.setSelectedFeatures(selran)
else:
vlayer.setSelectedFeatures(range(0, vlayer.featureCount()))
self.setOutputValue(RandomSelectionWithinSubsets.OUTPUT, filename)
def defineCharacteristics(self):
self.name = "Random selection within subsets"
self.group = "Research tools"
self.addParameter(ParameterVector(RandomSelectionWithinSubsets.INPUT, "Input layer", ParameterVector.VECTOR_TYPE_ANY))
self.addParameter(ParameterTableField(RandomSelectionWithinSubsets.FIELD, "ID Field", RandomSelectionWithinSubsets.INPUT))
self.addParameter(ParameterSelection(RandomSelectionWithinSubsets.METHOD, "Method", ["Number of selected features", "Percentage of selected features"]))
self.addParameter(ParameterNumber(RandomSelectionWithinSubsets.NUMBER, "Number of selected features", 1, None, 10))
self.addParameter(ParameterNumber(RandomSelectionWithinSubsets.PERCENTAGE, "Percentage of selected features", 0, 100, 50))
self.addOutput(OutputVector(RandomSelectionWithinSubsets.OUTPUT, "Selection", True))