[Rd] Wishlist: pass args from demo() to source()
Martin Maechler
maechler at stat.math.ethz.ch
Mon Nov 3 09:19:31 CET 2008
>>>>> "DM" == Duncan Murdoch <murdoch at stats.uwo.ca>
>>>>> on Sun, 02 Nov 2008 10:19:29 -0500 writes:
DM> On 02/11/2008 9:33 AM, Gabor Grothendieck wrote:
>> Currently demo calls source with a hard coded
>> max.deparse.length = 250 so you can't really see the demo
>> properly in some cases. Note the [TRUNCATED] below. (1)
>> It would be nice if demo passed max.deparse.length (and
>> other args to source). (2) Also a larger
>> max.deparse.length default would be nice to make it less
>> likely one would have to set it in the first place.
DM> I can see increasing the default, but it doesn't really
DM> seem like a good design to give extra args to demo().
DM> Would users ever know about them?
DM> So to me the choice would be to set a large
DM> max.deparse.length in the call to source() from demo().
DM> Just for fun, I tracked down the revision where the 250
DM> value was introduced: it was in r3045 in December 1998
DM> on
DM> https://svn.r-project.org/R/branches/R-0-63-patches/src/library/base/R/source.R,
DM> where the max was decreased from 10000 to 250. (The
DM> demo() function was in source.R in those days.) And the
DM> 10000 was added in r354 in December 1997 to
DM> https://svn.r-project.org/R/trunk/src/library/base/R/source,
DM> to remove the TRUNCATED message.
DM> Martin, is there any chance you remember what problem
DM> the 10000 caused? If those problems still exist, I'd
DM> add an arg to demo with 250 as the default, but if not,
DM> I'd say putting it back as 10000 would be reasonable.
No, I don't remember. The change in December 1998 you mention
contained more important things than s/10000/250/.
In the mean time, we have example() calling
source(..., max.deparse.length = Inf, ....)
and I think we should do the same for demo().
"Arbitrary limits" is against the GNU coding standards.
Martin
DM> Duncan Murdoch
>>
>>> R.version.string # Vista
>> [1] "R version 2.8.0 Patched (2008-10-21 r46766)"
>>> demo("gsubfn-si")
>>
>>
>> demo(gsubfn-si) ---- ~~~~~~~~~
>>
>> Type <Return> to start :
>>
>>> # given number possibly followed by SI letter
>>> (e.g. 32.5k where k means 1000) # replace letter with e
>>> followed by appropriate digits. # (see formatEng2R by
>>> Hans-Joerg Bibiko in the R Wiki)
>>>
>>> conv <- list(y = "e-24", z = "e-21", a = "e-18", f
>>> .... [TRUNCATED]
>>
>>> gsubfn(".$", conv, c("19", "32.5M"))
>> [1] "19" "32.5e6"
>>
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