[R] accessing info in object slots from listed objects using loops

[Henrique Dallazuanna]

Try this:

sapply(modelStack, slot, 'fit')['coef',]

On Wed, Mar 17, 2010 at 7:11 AM, torgrims <torgrims at stud.ntnu.no> wrote:
>
> Hey,
>
> I have stacked a couple of garchFit objects in a list with names $fit1,
> $fit2, ..., $fiti assigning objects names using a loop, i.e. after running
> the loop modelStack = list($fit1, $fit2,...,$fiti).
>
> Thus the following apply;
> a = modelStack$fit2, then a is the second garchFit object of formal class
> 'fGarch' with 11 slots, @call, @formula... etc.
>
> I then want to extract information in the 11 slots using another for loop,
> say i want to access the slot a at fit$coef. In order for this to happen I need
> to combine modelStack$fit2, where the $fit2 object name must be constructed
> in the loop, with the slot name @fit$coef.
>
> In order to construct the proper list names one could use the following in
> the for loop;
> name = paste("modelStack$fit",i,"@fit$coef",sep="")  #
> "modelStack$fit2 at fit$coef" for i = 2,
>
> and then use something like
> get(name)
>
> But this returns; Error in get(name) : object 'modelStack$fit2 at fit$coef' not
> found
>
> If I just type modelStack$fit2 at fit$coef in the command window it returns the
> proper info from the object list. I figure this is because R somehow
> interpret "$" and "@" in get() differently than $ and @ as "list
> separators".
>
> Does anyone know how to extract information in slots of listed objects using
> a loop and on the run generated variable/object names?
>
> JT
>
> sample code
>        nAssets = length(modelStack)
>
>        for(i in 1:nAssets){
>                name = paste("modelStack[",i,"]@name$series$h",sep="")
>                a = get(name)
>                      t = length(a)
>        } # end for loop
>
> --
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>
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>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O