[R] qoestion on insert a vector into a matrix

[jim holtman]

Try this:

> x <- matrix(0,10,5)
> vecToAdd <- 1:5
> # add to rows 1,4,8,9
> # need to transpose because of the way matrix is filled
> # this does not give the right result
> x[c(1,4,8,9),] <- vecToAdd
> x
      [,1] [,2] [,3] [,4] [,5]
 [1,]    1    5    4    3    2
 [2,]    0    0    0    0    0
 [3,]    0    0    0    0    0
 [4,]    2    1    5    4    3
 [5,]    0    0    0    0    0
 [6,]    0    0    0    0    0
 [7,]    0    0    0    0    0
 [8,]    3    2    1    5    4
 [9,]    4    3    2    1    5
[10,]    0    0    0    0    0
> x <- matrix(0,10,5) # refresh
> x <- t(x)
> x[, c(1,4,8,9)] <- vecToAdd # note adding to columns now
> t(x)  # put in back in the right orientation
      [,1] [,2] [,3] [,4] [,5]
 [1,]    1    2    3    4    5
 [2,]    0    0    0    0    0
 [3,]    0    0    0    0    0
 [4,]    1    2    3    4    5
 [5,]    0    0    0    0    0
 [6,]    0    0    0    0    0
 [7,]    0    0    0    0    0
 [8,]    1    2    3    4    5
 [9,]    1    2    3    4    5
[10,]    0    0    0    0    0
>
>


On Sat, Mar 6, 2010 at 12:21 PM,  <khazaei at ceremade.dauphine.fr> wrote:
> Hi,
> I want to add a vector many time to rows of the matrix without use the loop.
> could you please hint me?
> thanks
> khazei
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?