From murdoch.duncan at gmail.com  Thu Aug 19 23:25:22 2010
From: murdoch.duncan at gmail.com (Duncan Murdoch)
Date: Thu, 19 Aug 2010 17:25:22 -0400
Subject: [Rd] Does anyone use Sweave (RweaveLatex) option "expand=FALSE"?
In-Reply-To: <4C6D9D26.9060505@gmail.com>
References: <4C6D80E3.2090806@gmail.com> <4C6D9431.4020104@units.it>
	<4C6D9634.4030003@gmail.com> <4C6D9D26.9060505@gmail.com>
Message-ID: <4C6DA142.3090306@gmail.com>

On 19/08/2010 5:07 PM, Kevin Coombes wrote:
> I use it, frequently. The idea for it goes back to some of Knuth's 
> original literate programming ideas for developing weave and tangle when 
> he was writing TeX (the program).  I want to be able to document the 
> pieces of some complex algorithm without having to see all of the gory 
> details.  For instance, I have code that looks like the following.  
> (Note that this is typed on the fly rather than copied from actual 
> source, so there may be typos.)

Okay, thanks.  I'll keep it in.  So now I have a question:  suppose
you have an error (syntax error at this point, maybe some other kinds of 
error in the future) in the <<getInfoAboutThisSample>> chunk, but that 
chunk wasn't eval'd, mainloop was eval'd.  So the error is going to be 
reported as occurring in chunk mainloop, but with a line number from 
somewhere else in the file.  Is that a problem?

Duncan Murdoch


> 
> <<mainloop,keep.source=TRUE,expand=FALSE>>=
> for (i in 1:nSamples) {
> <<getInfoAboutThisSample>>
>  for (j in 1:nChromosomes) {
> <<getChromosomeDataForCurrentSample>>
> <<normalizeChromosomeData>>
> <<findSegments>>
> <<computeSignificance>>
> <<writeResults>>
>  }
> }
> @
> 
> Each of the <<chunks>> is itself a fairly long piece of code defined and 
> documented somewhere else.  (Some of them may themselves be written in 
> the same form to reduce the final size of a chunk to something a human 
> has a chance of understanding. That's the difference between weave and 
> tangle in the original implementation.)   By blocking expansion, I can 
> focus on the main steps without having them lost in pages and pages of code.
> 
> So I vote strongly for retaining "expand=FALSE".
> 
> Best,
>     Kevin
> 
> Duncan Murdoch wrote:
>> On 19/08/2010 4:29 PM, Claudia Beleites wrote:
>>> I never used it.
>>>
>>> I got curious, though. What would be a situation that benefits of 
>>> this option?
>>>   
>> When I put it in, I thought it would be for people who were writing 
>> about Sweave.
>>
>> Duncan Murdoch
>>
>>> Maybe a use case could be found by "brute force" (grep all .Rnw files 
>>> on CRAN for the option?
>>>
>>> Claudia
>>>
>>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel



[Rd] Does anyone use Sweave (RweaveLatex) option "expand=FALSE"?
Duncan Murdoch