[R] beginner's loop issue

[R. Michael Weylandt]

Yes, the short answer is that you need to define out before running
the loop. The most effective way to do so will be to set up a matrix
with the exact right dimensions (if you know them up front); something
like out <- matrix(NA, nrow = length(input), ncol = 9)

Michael



On Tue, Mar 13, 2012 at 12:27 PM, aledanda <danda.galli at gmail.com> wrote:
> Dear All,
>
> I hope you don't mind helping me with this small issue. I haven't been using
> R in years and I'm trying to fill in a matrix
> with the output of a function (I'm probably using the Matlab logic here and
> it's not working).
> Here is my code:
>
> for (i in 1:length(input)){
>  out[i,1:3] <- MyFunction(input[i,1],input[i,2], input[i,3])
>    out[i,4:6] <- MyFunction(input[i,5],input[i,7], input[i,6])
>      out[i,7:9] <- MyFunction(input[i,8],input[i,10], input[i,9])
> }
>
> 'input' is a matrix
>> dim(input)
> [1] 46 10
>
> and each raw corresponds to a different subject.
> The error I get here is
>
> /Error in out[i, 1:3] <- get.vaTer(input[i, 2], input[i, 4], input[i, 3],  :
>  object 'out' not found/
>
> So I wonder, what's wrong in the assignment to the variable out?
> Should I define the variable before the loop?
>
> Thanks for your help
> Best
>
> Ale
>
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