[Rd] Carriage returns and Sweave output

[Douglas Bates]

On 3/20/07, Ernest Turro <ernest.turro at ic.ac.uk> wrote:
>
> On 20 Mar 2007, at 07:53, Martin Maechler wrote:
>
> >>>>>> "Wolfi" == Wolfgang Huber <huber at ebi.ac.uk>
> >>>>>>     on Mon, 19 Mar 2007 15:38:00 +0000 writes:
> >
> >>> the problem with results=hide is that it suppresses everything. I
> >>> just
> >>> need Sweave to suppress strings ending in '\r'...
> >
> >
> >     Wolfi> Dear Ernest,
> >
> >     Wolfi> IMHO it is good practice to make the printing of these
> > progress reports
> >     Wolfi> ("sweep 4 of 1024\r") optional and produce them only if
> > the user calls
> >     Wolfi> your function with, say, "verbose=TRUE",
> >
> > I strongly agree.
> >
> >     Wolfi> and furthermore set the default value of the
> >     Wolfi> 'verbose' argument to "verbose=interactive()".
> >
> > or -- typically my choice -- to  'verbose = getOption("verbose")
> >
> > Martin Maechler, ETH Zurich
> >
> >     Wolfi> Best wishes
> >     Wolfi> Wolfgang
> >
> >  [............]
> >
>
> I agree that users should be free to choose the level of verbosity.
> Here, I want to show the verbose output and print it onto the tex
> file using Sweave to give users a good idea of what happens. What I
> don't want is countless lines being printed because \r is being
> interpreted as \n ...

In cases like this capture.output() is your friend.  Write one code
chunk with results=hide,echo=FALSE that uses capture.output to trap
the desired output as character strings then use string manipulation
functions to do the desired replacement.  A second code chunk with
eval=FALSE shows the code that apparently produces the output and a
third code chunk with echo=FALSE uses cat on the manipulated character
strings with quote=FALSE to show what apparently was produced.

> >>>> Ernest Turro wrote:
> >>>>> Dear all,
> >>>>> I have a code chunk in my Rnw file that, when executed, outputs
> >>>>> carriage return characters ('\r') to inform on the progress (e.g.
> >>>>> "sweep 4 of 1024\r"). But Sweave interprets this as a newline
> >>>>> character, and therefore I get countless pages of output in my
> >>>>> vignette where I only really want one line. Any ideas?
> >>>>> Thanks
> >>>>> E
>
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