For values in a matrix get value out of a vector and replace the matrix values

Question

Ok complicated title, but actually it's quite easy to explain :-)

I have a Matrix M:

M<-matrix(c(1,3,4,5,7,6,2, 2,5,1,3,4,7,6, 1,7,3,2,5,4,6),nrow=3,ncol=7, byrow=TRUE)
     [,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]    1    3    4    5    NA    6    2
[2,]    2    5    1    3    4    7    6
[3,]    1    7    3    2    5    4    NA

And I have a vector with weights W:

W<-c(0.4,0.2,0.15,0.1,0.07,0.05,0.02)

Now I want to replace all values in the matrix depending on the number in the matrix, with the value in the vector at this respective position. So my resulting Matrix (it needs to be a matrix) should look like this:

[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]  0.4  0.15 0.1   0.07  NA  0.05  0.2
[2,]  0.2  0.07 0.4   0.15  0.1   0.02  0.05
[3,]  0.4  0.02 0.15  0.2   0.07  0.1   NA

But I don't know how to achieve this.

M2<-W[M]

didn't achieve the desired results..any advice?

Answer 1

matrix(W[M], nrow=nrow(M))

     [,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]  0.4 0.15 0.10 0.07   NA 0.05 0.20
[2,]  0.2 0.07 0.40 0.15 0.10 0.02 0.05
[3,]  0.4 0.02 0.15 0.20 0.07 0.10   NA