[R] is there a way to let R do smart matrix-vector operation?

Liaw, Andy andy_liaw at merck.com
Tue Mar 7 00:20:51 CET 2006


It's rarely necessary to have a vector in matrix form.  In this case, it
actually make things harder.  If B had been a vector, you would have gotten:

> A=matrix(c(2:7), 2, 3)
> B=matrix(c(1, 2), 2, 1)
> A - as.vector(B)
     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    1    3    5

Andy

From: Michael
> 
> Hi all,
> 
> I want to substract vector B from A's each column... how can 
> R do that smartly without a loop?
> 
> > A=matrix(c(2:7), 2, 3)
> > A
>      [,1] [,2] [,3]
> [1,]    2    4    6
> [2,]    3    5    7
> > B=matrix(c(1, 2), 2, 1)
> > B
>      [,1]
> [1,]    1
> [2,]    2
> > A-B
> Error in A - B : non-conformable arrays
> 
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> 
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