Hi, 2012/8/2 Margherita Di Leo <dileomargherita at gmail.com>: >> grass.run_command('r.clump', input = 'r_flood', output = >> 'r_clump', flags = '-o') flags = '-o' is wrong, should be 'overwrite = True'. Martin -- Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa