[R] Fwd: for loop

[Michael Bedward]

First up, you've got a problem if your vectors are 520 elements in
length because you accessing element i+1 in your loop and when i is
520 you won't have a valid value.

Next, you don't really need a for loop at all :)  You can do those
operations on the whole vectors...

e.g. tmp1 <- (1 - samp.pct[-n)^2 * diff(log(1 - theor.pct))

(just replaced your explicit subtraction of lagged values with diff)

Does that help ?

Michael


Note, in the line above, the last element is omitted with "[-n]". See
help page on the diff function if you are not familiar with it.

On 21 September 2010 16:41, andre bedon <andresago1 at hotmail.com> wrote:
>
> Hi guys,
>
> Im new to R and am having a bit of trouble with what should be a simple loop. It sprobably something very fundamental that im doing wrong.
>
>
>
> for(i in c(1:520))
> {
> tmp1<- ((1-samp.pct[i])^2)*(log(1-theor.pct[i])-log(1-theor.pct[i+1]))
> tmp2<- ((samp.pct[i])^2)*(log(theor.pct[i+1])-log(theor.pct[i]))
> }
> ADtest.stat<- (-n*(max(theor.pct))) + (n*sum(tmp1)) + (n*sum(tmp2))
> names(ADtest.stat) <- c("Anderson-Darling test statistic")
> print(ADtest.stat)
>
>
>
> samp.pct is a vector containing 520 values between 0 and 1, so is theor.pct. n is 520.
>
> After running this code, tmp1 and tmp2 return only one value, where I need around 520 values. Any ideas would be appreciated.
>
>
>
> Regards,
>
>
>
> Andre
>
>
>
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