Le portail francophone de la géomatique

def main():

 def init():

   # appel de l'application et initialisation
   a = QgsApplication(sys.argv, True)
   QgsApplication.setPrefixPath("C:/OSGeo4W/apps/qgis", True)
   QgsApplication.initQgis()
   return a

 def show_shape(app):

    # definition a connection
    uri = QgsDataSourceURI()
    uri.setConnection("localhost", "5432", "stat", "postgres", "admin")
    uri.setDataSource("public", "com", "the_geom", ' ', "gid")
    uri.uri()

    # création d'une fenêtre et chargement d'une couche
    carte = QgsMapCanvas()
    layer=QgsVectorLayer(uri.uri(), 'com', 'postgres')
    if not layer.isValid():
       print "Layer failed to load!"

    # add layer to the registry
    QgsMapLayerRegistry.instance().addMapLayer(layer)
    carte.setExtent(layer.extent())

    # affichage de la couche dans une fenêtre
    carte.setLayerSet( [ QgsMapCanvasLayer(layer) ] )
    carte.show()

    #personnaliser la symbologie
    myTargetField = 'code'
    myRangeList = []
    myOpacity = 1

    # Make our first symbol and range...
    myMin = 0.0
    myMax = 100.0
    myLabel = '0.0-200'
    myColour = QtGui.QColor('white')#ffee00
    mySymbol1 = QgsSymbolV2.defaultSymbol(layer.geometryType())
    mySymbol1.setColor(myColour)
    mySymbol1.setAlpha(myOpacity)
    myRange1 = QgsRendererRangeV2(myMin,myMax,mySymbol1,myLabel)
    myRangeList.append(myRange1)

    #now make two symbol and range...
    myMin = 100.1
    myMax = 102
    myLabel = '200.1-500'
    myColour = QtGui.QColor('yellow')#00eeff
    mySymbol2 = QgsSymbolV2.defaultSymbol(layer.geometryType())
    mySymbol2.setColor(myColour)
    mySymbol2.setAlpha(myOpacity)
    myRange2 = QgsRendererRangeV2(myMin,myMax,mySymbol2,myLabel)
    myRangeList.append(myRange2)

    myRenderer = QgsGraduatedSymbolRendererV2('', myRangeList)
    myRenderer.setMode(QgsGraduatedSymbolRendererV2.EqualInterval)
    myRenderer.setClassAttribute(myTargetField)

    layer.setRendererV2(myRenderer)
    QgsMapLayerRegistry.instance().addMapLayer(layer)
    print "fine"

    app.exec_()

 app = init()
 show_shape(app)

if __name__ == "__main__":
    main()

# display legend
legend = QgsComposerLegend(c)
legend.model().setLayerSet(mapRenderer.layerSet())
c.addItem(legend)