[R] 'programatically' list or call objects for use in a function?

[Karl Brand]

Cheers Duncan, for your FAST answers and patience. (fast patience?!)

I was close. But closer reading of ?save would also have worked i see 
now :$. LETTERS[] = :)

thanks again,

Karl

On 9/11/2010 2:10 PM, Duncan Murdoch wrote:
> On 11/09/2010 8:00 AM, Karl Brand wrote:
>> Esteemed R users and developers,
>>
>> How does one 'programatically' list or call objects for use in a
>> function?
>
> It depends on the function.
>
>>
>> For example, i thought i could do something better than this:
>>
>> save(A.cwb, B.cwb, C.cwb, D.cwb, E.cwb, F.cwb, file="afile.RData")
>>
>> with something like these-
>>
>> prfxs <- c("A", "B", "C", "D", "E", "F") #**
>> save(as.name(paste(prfxs, "cwb", sep=".")), file="afile.RData")
>
> For save, use list=paste(prfxs, "cwb", sep=".").
>
>>
>> or this-
>>
>> do.call(save, paste(prfxs, "cwb", sep="."), file="afile.RData")
>
> do.call wants a *list* of arguments, not a single vector of character
> strings. You could construct a list of the names of the objects you want
> to save, but that's a pain. Just use the list= argument (which doesn't
> want a list argument :-).
>
>>
>> Both failed.
>>
>> #** And while i've got your attention- is there a 'letter equivalent'
>> to seq() which would have worked nicely for prfxs? ie., letter.seq(A:F)
>
> Not that I know of, but LETTERS[1:6] will give you the sequence, and
> it's easy to write a function that you'd call as letter.seq("A", "F").
> Having your function work as in your example would be messy.
>
> Duncan Murdoch
>
>>
>> Thoughts and suggestions sincerely appreciated,
>>
>> Karl
>>
>>
>>
>

-- 
Karl Brand
Department of Genetics
Erasmus MC
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