On 16-Aug-05 ISAIAH SHALWITZ wrote: > This seems like a simple problem but I can't figure it out: > > I have two identical DIMENSION matrices. Both contain only binary > values NOT identical between matrices. What I want to do: If in cell > (1,1) the value in the first matrix (x) equals 1, then I keep the value > in cell (1,1) in the second matrix (y). If in cell (1,1) the value in > the first matrix (x) equals 0, then I change the value in cell (1,1) in > the second matrix (y)to missing (NA). Repeat for every pair of cells > (coordinates of the paired cells always match). > > Please help.
It seems the following is what you are looking for: A<-matrix(c(1,0,1,0,1,1,1,1,1),nrow=3) A # [,1] [,2] [,3] # [1,] 1 0 1 # [2,] 0 1 1 # [3,] 1 1 1 B<-matrix(c(1,2,3,4,5,6,7,8,9),nrow=3) B # [,1] [,2] [,3] # [1,] 1 4 7 # [2,] 2 5 8 # [3,] 3 6 9 B[A==0]<-NA B # [,1] [,2] [,3] # [1,] 1 NA 7 # [2,] NA 5 8 # [3,] 3 6 9 Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 16-Aug-05 Time: 09:08:25 ------------------------------ XFMail ------------------------------ ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html