[R] parsing '...' function argument?

From: Oleg Sklyar <osklyar_at_ebi.ac.uk>
Date: Thu 30 Jun 2005 - 20:41:30 EST

Dear community,

I am writing a wrapper for '[' operator, which is a generic method declared as function(x, i, j, ..., drop). It turns out that I need to parse the '...' argument and this is where I am stuck. Generally what I need is the following. Say the call is obj[1, 1, 1:10, 3] - here '1:10, 3' is passed into '...'. What I need to evaluate that '...' contains now 2 arguments, first is a vector of 10 elements and second is a single value. Even nicer situation is in call obj[1, 1, , 3] - where ' , 3' is passed in '...' with one missing argument, which for an array would mean the full range. Any ideas? (Just to mention - if there were only one argument in '...', say '1:10', then length(...) would return 10 and one could access elements by ...[[i]], but all this fails if there are two arguments or more).


Dr Oleg Sklyar
European Bioinformatics Institute
Wellcome Trust Genome Campus
Hinxton, Cambridge
CB10 1SD
United Kingdom

tel +44 1223 492537
fax +44 1223 494468
email osklyar@ebi.ac.uk

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Received on Thu Jun 30 20:46:07 2005

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