Sebastian Hungerecker wrote: > Li Chen wrote: >> How do I change all the As into T and all the Ts into >> A in the old sttring? >> >> old_s="AAATTAA" >> new_s="TTTAATT" > > new_s = old_s.tr("AT", "TA") > or if you also want GC > new_s = old_s.tr("ATGC", "TACG") Thank you very much, Li -- Posted via http://www.ruby-forum.com/.