[Rd] Warnings generated by log2()/log10() are really large/takes a long time to display

[Richard Pearson]

Yes Henrik, I've also noticed this when cutting and pasting code from here:

http://ace.acadiau.ca/math/ACMMaC/Rmpi/sample.html

Try the .Last function for example.

Best wishes

Richard.


Henrik Bengtsson wrote:
> On Wed, Feb 27, 2008 at 12:56 AM, Prof Brian Ripley
> <ripley at stats.ox.ac.uk> wrote:
>   
>> On Wed, 27 Feb 2008, Martin Maechler wrote:
>>
>>  > Thank you Henrik,
>>  >
>>  >>>>>> "HenrikB" == Henrik Bengtsson <hb at stat.berkeley.edu>
>>  >>>>>>     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 at r-project.org mailing list
>>  > https://stat.ethz.ch/mailman/listinfo/r-devel
>>  >
>>
>>  --
>>  Brian D. Ripley,                  ripley at stats.ox.ac.uk
>>  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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