HI, Try this: A<-matrix(c(0,NA,NA,3),ncol=2) B<-matrix(c(1,0,NA,NA),ncol=2) C<-matrix(c(1,1,NA,1),ncol=2) AB<-ifelse(is.na(A),ifelse(is.na(B),NA,B), ifelse(is.na(B), A, A+B)) ABC<-ifelse(is.na(AB),ifelse(is.na(C),NA,C),ifelse(is.na(C),AB,AB+C)) ABC [,1] [,2] [1,] 2 NA [2,] 1 4
A.K. ----- Original Message ----- From: Thiago Couto <[email protected]> To: [email protected] Cc: Sent: Monday, July 23, 2012 4:47 PM Subject: [R] help with element-by-element sum with NA Hi, I have three matrices which could be, for example: A = 0, NA NA, 3 B = 1, NA 0, NA C = 1, NA 1, 1 (The point is that they all may have NA's in some cells) QUESTION: How do I perform a element-by-element sum of the elements of these three matrices (A + B + C), ignoring NA's, to obtain: D = 2, NA 1, 4 In reality I am handling much larger matrices (not just 2x2). Thank you for any help! [[alternative HTML version deleted]] ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
