On Jan 19, 2009, at 3:54 PM, Dimitris Rizopoulos wrote:
try this:
A <- matrix(c(3,3,3,3,3,3,3,3,3),3,3)
B <- matrix(c(T,T,T,F,T,T,F,T,F),3,3)
C <- A
C[!B] <- NA
C
Very elegant. Another, perhaps less elegant, effort:
B[which(B == FALSE)] <- NA
> B
[,1] [,2] [,3]
[1,] TRUE NA NA
[2,] TRUE TRUE TRUE
[3,] TRUE TRUE NA
> C <- matrix(A * B, 3,3) # A * B is *not* matrix multiplication
>
>
> C
[,1] [,2] [,3]
[1,] 3 NA NA
[2,] 3 3 3
[3,] 3 3 NA
--
David Winsemius
I hope it helps.
Best,
Dimitris
Andrej Kastrin wrote:
Dear all,
Suppose that I have a matrix A
A <- matrix(c(3,3,3,3,3,3,3,3,3),3,3)
and a logical matrix B
B <- matrix(c(T,T,T,F,T,T,F,T,F),3,3)
The result matrix should be
C <- matrix(c(3,3,3,NA,3,3,NA,3,NA),3,3)
Is there any simple tip or trick to perform this without looping?
Thanks in advance for any suggestion.
Best regards, Andrej
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--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org 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.
