[R] Running sum
Marc Schwartz
MSchwartz at MedAnalytics.com
Fri Nov 19 19:57:24 CET 2004
On Fri, 2004-11-19 at 13:08 -0500, Sean Davis wrote:
> I have vector X of length N that I want to have a running sum for
> (called Y). I just need max(Y). I do this with a "for" loop like so:
>
> Y <- vector(length=N)
> Y[1] <- X[1]
> for (i in 2:N) {
> Y[i] <- Y[i-1]+X[i]
> }
> return(max(Y))
>
> Is there a faster way to do this?
>
> Thanks,
> Sean
Something like:
> cumsum(1:10)
[1] 1 3 6 10 15 21 28 36 45 55
> max(cumsum(1:10))
[1] 55
Does that help?
Marc Schwartz
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