On Wed, Feb 27, 2008 at 12:56 AM, Prof Brian Ripley
<[EMAIL PROTECTED]> wrote:
> On Wed, 27 Feb 2008, Martin Maechler wrote:
>
> > Thank you Henrik,
> >
> >>>>>> "HenrikB" == Henrik Bengtsson <[EMAIL PROTECTED]>
> >>>>>> on Tue, 26 Feb 2008 22:03:24 -0800 writes:
> >
> > {with many superfluous empty statements ( i.e., trailing ";" ):
>
> Indeed!
I like to add a personal touch to the code I'm writing ;)
Seriously, I added them here as a bait in order to get a chance to say
that I finally found a good reason for adding the semicolons. If you
cut'n'paste code from certain web pages it may happen that
newlines/carriage returns are not transferred and all code is pasted
into the same line at the R prompt. With semicolons you still get a
valid syntax. I cannot remember under what conditions this happened -
if it was for certain web browser, web page/blog, online page editor,
OS and so, but I'm quite sure it was while I've put online code
examples for my latest project. Maybe someoneelse also has noticed
this?
>
>
>
> > HenrikB> x <- rnorm(1e6);
> >
> > [................]
> >
> >
> > HenrikB> y <- log2(x); # or log10(x)
> > HenrikB> w <- warnings();
> > HenrikB> print(object.size(w));
> > HenrikB> ## [1] 8000536
> > HenrikB> str(w);
> > HenrikB> ## List of 1
> > HenrikB> ## $ NaNs produced: language log(c(2.12082478659910,
> > HenrikB> 1.40263187453398, 1.574125429
> > HenrikB> ## 83486, -0.816399069824751, 0.215940065840533,
> 1.20975177084379,
> > HenrikB> -0.340287874362
> > HenrikB> ## 813, 0.117151537611550, ...
> > HenrikB> ## - attr(*, "dots")= list()
> > HenrikB> ## - attr(*, "class")= chr "warnings"
> >
> > HenrikB> Note also how long it takes to display and str() the warning.
> >
> > Yes, indeed.
> > It's a subtle problem and happens
> > because in do_log1arg() a new call is constructed in which 'x'
> > has already been evaluated.
> >
> > A subtle fix to the subtle problem
> > is to replace CAR(args) by CADR(call) in there
> >
> > --- arithmetic.c (Revision 44626)
> > +++ arithmetic.c (working copy)
> > @@ -1372,7 +1372,9 @@
> > if(PRIMVAL(op) == 10) tmp = ScalarReal(10.0);
> > if(PRIMVAL(op) == 2) tmp = ScalarReal(2.0);
> >
> > - PROTECT(Call = lang3(install("log"), CAR(args), tmp));
> > + /* CADR(call) instead of CAR(args), since 'args' have been
> > + * evaluated in Dispatch*(..) above : */
> > + PROTECT(Call = lang3(install("log"), CADR(call), tmp));
> > res = eval(Call, env);
> > UNPROTECT(1);
> > return res;
> >
> > -----
> >
> > That does fix the problem you've reported (and passes "make check")
> > but I'm not quite at ease with it, since it will lead to
> > effectively evaluate the argument *twice*.
> >
> > A different approach that I'd find cleaner
> > would be to *not* construct and eval() a
> > new Call inside do_log1arg, but I assume there had been a good
> > reason for doing things they way they are now...
>
> There was (although possibly no longer -- there was a bug in S4 dispatch
> of primitives that failed to re-promise args).
>
> The real issue is somewhere else entirely, the complete deparse in
> print.warnings.
Thank you both for looking into this.
Henrik
>
> >
> > Martin Maechler, ETH Zurich
> >
> > ______________________________________________
> > R-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
>
> --
> 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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