[R] Setting width in batch mode

[Friedrich.Leisch@tuwien.ac.at]

>>>>> On Thu, 8 Sep 2005 15:01:23 -0400 (EDT),
>>>>> Jonathan Dushoff (JD) wrote:

  > As instructed, I have spent a long time searching the web for an answer
  > to this question.

  > I am trying to use Sweave to produce lecture slides, and have the
  > problem that I can't control the formatting of my R source.  Setting
  > options(width), as recommended in this forum, works fine on the R
  > _output_, but seems to have unpredictable effects on the echoing of the
  > source code.

  > If I try setting options(width) directly in R, I note that it has _no_
  > effect on echoed source code, whereas Sweave does sometimes break source
  > code, but not predictably, and not to the same width as output code.

  > I would be happy with any method of manually or automatically
  > controlling the line width of Sweave source, using R, Sweave or LaTeX
  > options.  Making the font smaller does not count, though; I want to
  > break the lines.

  > Any help is appreciated.

  > An example of Sweave input and output is appended.

  > The last break is right, while the others are too late.

The deparser of R only *tries* to break lines at the given cutoff
(Sweave uses 0.75*getOption("width") for input lines), so you
soemtimes have to play a little bit, and yes, results are somewhat
unpredictable. After storing your code in file ex1.R I get:

R> expr=parse("ex1.R")
R> length(expr)
[1] 5

R> for(n in 1:length(expr)) print(deparse(expr[[n]], width.cutoff=.75*55))
[1] "options(width = 55)"
[1] "data(state)"
[1] "data.frame(area = mean(state.area), pop = mean(state.pop), "
[2] "    hop = mean(state.area))"                                
[1] "c(medianarea = median(state.area), medianpop = median(state.pop))"
[1] "c(medianarea = median(median(state.area)), "
[2] "    medianpop = median(state.pop))"         

R> for(n in 1:length(expr)) print(deparse(expr[[n]], width.cutoff=.75*45))
[1] "options(width = 55)"
[1] "data(state)"
[1] "data.frame(area = mean(state.area), "              
[2] "    pop = mean(state.pop), hop = mean(state.area))"
[1] "c(medianarea = median(state.area), "
[2] "    medianpop = median(state.pop))" 
[1] "c(medianarea = median(median(state.area)), "
[2] "    medianpop = median(state.pop))"         


I know that's not exactly the answer you were looking for, but that's
the way it is. I'll add a sentence or two to the FAQ.

Best,

-- 
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                        Friedrich Leisch 
Institut für Statistik                     Tel: (+43 1) 58801 10715
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