[R] finding a faster way to do an iterative computation

[Moshe Olshansky]

Try

abs(outer(xk,x,"-"))

(see ?outer)


--- On Wed, 30/7/08, dxc13 <dxc13 at health.state.ny.us> wrote:

> From: dxc13 <dxc13 at health.state.ny.us>
> Subject: [R]  finding a faster way to do an iterative computation
> To: r-help at r-project.org
> Received: Wednesday, 30 July, 2008, 4:12 AM
> useR's,
> 
> I am trying trying to find out if there is a faster way to
> do a certain
> computation.  I have successfully used FOR loops and the
> apply function to
> do this, but it can take some time to fully compute, but I
> was wondering if
> anyone may know of a different function or way to do this:
> > x
> [1] 1 2 3 4 5
> > xk
>  [1] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
> 
> I want to do: abs(x-xk[i]) where i = 1 to length(xk)=13. 
> It should result
> in a 13 by 5 matrix or data frame.  Does anyone have a
> "quicker" solution
> than FOR loops or apply()?
> 
> Much appreciation and thanks,
> dxc13
> -- 
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