[R] fusion of two matrices (numerical and logical)

[Bert Gunter]

A is not a matrix. I presume you meant B. If so:

> B[!C] <- 0
> B
     [,1] [,2] [,3] [,4]
[1,]    1    6    0    0
[2,]    2    0    0    0
[3,]    3    0    0    0
[4,]    4    0    0   19
[5,]    5    0    0    0

Cheers,
Bert





On Sat, Sep 5, 2020 at 11:18 AM Vivek Sutradhara <viveksutra using gmail.com>
wrote:

> Hi
> I would like to get help in combining two matrices. Here is my example:
> A <- 1:20
> B <- matrix(A,nrow=5,ncol=4)
> # B is a numerical matrix
> C <- B<7
> C[4,4] <- TRUE
> # C is a logical matrix
> # if I combine A and C, I get a vector
> D1 <- A[C==TRUE]
> D1
> D2 <- A[C==FALSE]
> D2
>
> I want to get a matrix with the same dimensions as matrix A. At the
> coordinates given by the vector D1, I want to retain the values in
> matrix A. At the locations in D2, I want a zero value.
> I want to know if I can do this without using any loops.
> Thanks, Vivek
>
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