[R-SIG-Finance] turning returns back into an index

[Pierre Lapointe]

cumprod(1+return_vector) to get an index starting from 1.
cumprod(1+return_vector)*100 to get an index starting at 100

On Sun, May 14, 2017 at 9:11 AM, blank <bruvnor at icloud.com> wrote:

> I’ve looked everywhere for a C optimised R library function that will
> accumulate returns with interim levels but can’t find it.
>
> so a function that is the inverse of Return.calculate() from
> PerformanceAnalytics
>
> or, something like this:
>
> rtns <- rnorm(100, sd=0.01)
> index <- vector(, length = length(rtns)+1)
> index[1] <- 100
> for ( i in 1:length(rtns) ) {
>   index[i+1] <- index[i] * (1+rtns[i])
> }
>
> cheers.
>
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