def zonalStat(self, vlayer, rlayer_source):
prefix = 'Erosion_G_'
zonalstats = QgsZonalStatistics(vlayer, rlayer_source, prefix, stats=QgsZonalStatistics.Statistic(4))
zonalstats.calculateStatistics(None)
vlayer.startEditing()
for field in vlayer.pendingFields():
if field.name() == 'Erosion_G_':
idx = vlayer.fieldNameIndex(field.name())
vlayer.renameAttribute(idx, 'G')
vlayer.commitChanges()
