layer = QgsVectorLayer('/home/hbecerra/Desktop/temp/manzanas_iter.shp',
'masde1000', 'ogr')
query = '"pobtot" > 1000'
QgsMapLayerRegistry.instance().addMapLayer(layer)
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.setSelectedFeatures([k.id() for k in selection])