Many mathematical structures/sequences start ``naturally'' from 0
rather than from 1, making it convenient to index vectors and array
dimensions by sequences starting from 0.
In APL (anybody else remember that language? I once saw it compared
to a car which drives only in reverse gear and is instrumented in
Greek) there was a simple way of selecting 0-origin rather than 1-origin
for sequence indexing. This seems not to be possible in S(plus).
Question 1: Might the designers of S(plus) consider adding, in some
future release, a 0-origin switch, say to the options() function? I
have in mind something like being able to say:
> options(origin=0)
after which
> x[0:3,]
would give me the first, second, third, and fourth rows of the matrix x.
Later I would like to be able to restore normalcy by saying
> options(origin=1)
Would this be feasible/easy/difficult/impossible given S(plus)'s
internal structure?
It is pretty clear that if you invoked
> options(origin=0)
and then called upon a function which was written assuming 1-origin,
then the sky would almost surely fall. As far as I'm concerned, that's
quite alright and it's the user's responsibility to make sure that
such invocations do not occur.
Question 1a: What about R? Would such a feature be any easier
(or harder?) to incorporate into R?
Question 2: Am I absolutely correct in asserting that 0-origin is
not currently available in S(plus)? I.e. is there any sort of
work-around that would enable one to fake 0-origin in a moderately
convenient way?
cheers,
Rolf Turner
rolf@math.unb.ca
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