Thanks Duncan and Romain! cumsum is exactly what I was looking for!
On 12/11/07, Romain Francois <[EMAIL PROTECTED]> wrote:
>
>
> Hi,
>
> It's not just the for loop, you are also growing objects in your code (z).
> Consider ?cumsum
>
> Cheers,
>
> Romain
>
> --
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>
> -----Original Message-----
> From: [EMAIL PROTECTED] on behalf of tom soyer
> Sent: Tue 11/12/2007 11:17
> To: r-help@r-project.org
> Subject: [R] Alternative to For Loop?
>
> Hi,
>
> I am doing a calculation on a long series using a For Loop. Here is an
> example of the calculation:
>
> accumulate=function(x){
> y=0
> z=0
> for(i in 1:length(x)){
> y=y+x[i]
> z=c(z,y)
>
> }
> return(z[2:length(z)])
> }
>
> > x=c(1:10)
> > x
> [1] 1 2 3 4 5 6 7 8 9 10
> > accumulate(x)
> [1] 1 3 6 10 15 21 28 36 45 55
> >
>
> Although the For Loop works, looping through an array is time consuming
> and
> inefficient when the series is large. Does anyone know a faster way of
> doing
> the same calculation? Thanks!
>
> --
> Tom
>
> [[alternative HTML version deleted]]
>
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>
--
Tom
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