How to shift each row of a matrix in R

Question

I have a matrix of this form:

a b c
d e 0
f 0 0

and I want to transform it into something like this:

a b c
0 d e
0 0 f
         


        

Answer 1

I think this is all you need:

 mat<-matrix(1:25,5)
 mat
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    2    7   12   17   22
[3,]    3    8   13   18   23
[4,]    4    9   14   19   24
[5,]    5   10   15   20   25
 for(j in 2:nrow(mat) ) mat[j,]<-mat[j, c(j:ncol(mat),1:(j-1))]
 mat
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    7   12   17   22    2
[3,]   13   18   23    3    8
[4,]   19   24    4    9   14
[5,]   25    5   10   15   20