df[1:2]<-df[1:2]*-1 ----- Lanna Jin lannajin at gmail.com 510-898-8525 -- View this message in context: http://r.789695.n4.nabble.com/short-question-about-data-frame-manipulation-tp2076891p2076899.html Sent from the R help mailing list archive at Nabble.com.