Conditional Matrices

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.


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Date: 16-Aug-05                                       Time: 09:08:25
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