R-beta: A vector of lists == Data Frame?
fear at scmp.scm.liv.ac.uk
Mon Nov 3 11:41:41 CET 1997
> What is the most common R/S idiom for creating a vector of lists and
> then adding new lists to it?
I would suggest you use a list of lists instead of a vector of lists. If as you
say you are a real beginner in R/S (but obviously not to programming), are you
aware of use of double brackets to get list elements? ie mylist[i] returns the
element as a list of length one, almost always not what you want, which is
mylist[[i]]. Given this, lists are pretty easy to use; in fact, you can do
without vectors. As Ross Ihaka says, this would probably be more natural in
Xlispstat or straight Lisp.
BTW To find out about R's object-oriented methods, you need help(class);
help(object) draws a blank.
I'm sending this to the list because I'm interested in views re Ross' comment:
> Trying to work using record-like ideas is at best awkward in S/R and
> it will probably be very inefficient.
And yet StatSci do so love to peddle S-PLUS as object-oriented. An object
Person, a constructor Person() and a holder for them, PersonList, is totally
natural and efficient in a real object-oriented environment such as C++. Such
objects would have to be implemented using the fundamental list construct within
S/R. Is this really so inefficient? If so why?
Personally I think selling S-PLUS as object-oriented might be a prosecutable
offence. It is object-added. (R is free: I don't care what it claims to be :-)
scf at liv.ac.uk
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