On Fri, 10 Dec 2004, Peter Dalgaard wrote:
Martin Maechler <[EMAIL PROTECTED]> writes:
RichOK> "from", "to", "by", "length.out", "along.with" RichOK> ^^^^ ^^^^^ RichOK> when the help page for seq documents them as RichOK> "from", "to", "by", "length", and "along"?
Well I can explain why this wasn't caught by R's builtin QA (quality assurance) checks:
The base/man/seq.Rd page uses both \synopsis{} and \usage{} which allows to put things on the help page that are not checked to coincide with the code... I'm about to fix this (documentation, not code).
In the case of "length", I think there's a historical explanation for having the formal argument being a slightly lengthened version of what you'd like to use as the actual argument: "length" is the obvious choice of name for the argument, but if you used that in older versions of S and R then it would mask the length() function and get you in all sorts of trouble, or at least spit out a number of annoying warning messages. (On a related note, you may have noticed that some of the oldtimers still have knee-jerk reactions to people using "c" and "t" for variable names). So call it something longer and let partial matching allow users to use the short form.
With namespaces, base::length(v) would clear up the issue quite nicely, as would the convention of looking for objects of mode "function" if it is clear from the context that a function is needed. However, seq() predates both of these features as far as I remember.
Indeed, seq() is a Blue Book function, but with args `length' and `along'. R seems to have followed S-PLUS 3.x in using length.out and along.with: they were there in 1998-03-06, the earliest copy I can get hold of from SVN.
-- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
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