workers.py

# coding=utf-8
# Clusterpy QGIS plugin - (C) 2014, RiSE Group

from qgis.core import *
from PyQt4 import QtCore, QtGui

__all__ = ['MaxPWorker']
from clusterpy import ClusterpyFeature, execmaxp, validtopology

class Worker(QtCore.QObject):
    finished = QtCore.pyqtSignal(bool, basestring)
    progress = QtCore.pyqtSignal(float)

    def __init__(self):
        QtCore.QObject.__init__(self)

    def run(self):
        pass

class MaxPWorker(Worker):
    ERROR_MSG = u"There are features from the shapefile that are disconnected. \
                Check the areas identified with the following IDs for errors \
                in the geometry: "

    def __init__(self, info={}):
        super(Worker, self).__init__()
        for prop in info:
            self.__dict__[prop] = info[prop]

    def run(self):
        provider = self.layer.dataProvider()
        curr = [ fl.name() for fl in provider.fields() ]
        nfn = newColumnName(curr)
        maxpfield = QgsField(name = nfn, type = 2)
        newfields = QgsFields()
        newfields.extend(provider.fields())
        newfields.append(maxpfield)

        bad_value = -1
        clspyfeatures = {}
        for feat in provider.getFeatures():
            uid = feat.id()
            featids = []
            for _ftr in provider.getFeatures():
                if feat != _ftr and feat.geometry().touches(_ftr.geometry()):
                    featids.append(_ftr.id())
            neighbors = set(featids)
            neighbors.discard(uid)
            thresholdval = feat.attribute(self.thresholdattr)
            attributeval = feat.attribute(self.attrname)

            if thresholdval == None or attributeval == None:
                bad_value = uid
                break

            clspyfeatures[uid] = ClusterpyFeature(uid, thresholdval,
                                                neighbors, attributeval)

        outputmsg = None
        valid = True
        if bad_value != -1:
            valid = False
            outputmsg = "Please review feature with ID: " + str(bad_value) +\
            " and assign a numeric value to the NULL or empty attributes."
        else:
            valid, islands = validtopology(clspyfeatures)
            if valid:
                self.progress.emit(1.0)
                regions = execmaxp(clspyfeatures,
                                    self.threshold,
                                    self.maxit,
                                    self.tabusize,
                                    self.tabumax,
                                    self.progress.emit)
                self.progress.emit(95.0)
                newlayer = QgsVectorFileWriter( self.output_path,
                                                            None,
                                                            newfields,
                                                            provider.geometryType(),
                                                            provider.crs())

                for area in self.layer.getFeatures():
                    newarea = QgsFeature()
                    newarea.setGeometry(area.geometry())
                    attrs = area.attributes()
                    attrs.append(regions[area.id()])
                    newarea.setAttributes(attrs)
                    newlayer.addFeature(newarea)

                del newlayer
                outputmsg = self.output_path
            else:
                outputmsg = self.ERROR_MSG + str(map(str, islands))
        self.progress.emit(100.0)
        self.finished.emit(valid, outputmsg)

# Get the name of the next MAXP execution column.
def newColumnName(fields, basename = 'MAXP'):
    last = -1
    for fld in fields:
        if fld.startswith(basename):
            try:
                cnt = int(fld[len(basename):])
                last = cnt if cnt > last else last
            except ValueError:
                last = 0

    num = ""
    if last >= 0:
        num = str(last + 1)

    return basename + num