Hi to all members, i encountered a weird problem when trying to assign subset of rows in a matrix. Simple example works fine: z<-matrix(NA,ncol=3,nrow=10) z[,1]<-1:10 y<-matrix(1:30,ncol=3,nrow=10) y[,1]<-5:14 z[z[,1]%in%y[,1],2]<-y[y[,1]%in%z[,1],2] z z[z[,1]%in%y[,1],]<-y[y[,1]%in%z[,1],] z When i try it on a bigger matrix it works fine when i try to assign 1 element, but converts original matrix to a list when trying to assign 2 or 3 columns for example. What can be a problem, as it seems that matrices are both numbers only? Thanks -- View this message in context: http://www.nabble.com/Rows-assignment-tp16896591p16896591.html Sent from the R help mailing list archive at Nabble.com.