[Rd] Bug in Sweave? -- scoping problem? (PR#8615)

Friedrich.Leisch@tuwien.ac.at Friedrich.Leisch at tuwien.ac.at
Mon Feb 20 09:37:40 CET 2006

I will add it to the FAQ.


>>>>> On Sun, 19 Feb 2006 08:42:09 -0500,
>>>>> Duncan Murdoch (DM) wrote:


>       Code in chunks that produce pictures is executed several times.
>       First, to produce the output in the text.  And then once more
>       for *each* format in which the figure has to be produced.  I.e.,
>       if you want a PDF and a PostScript version of the figure, the
>       code is executed a total of three times.

  > Thanks, that's what caught me.  Is that a quote from the discussion, or 
  > from the docs somewhere?  It makes sense in hindsight, but it's not 
  > obvious ahead of time, so it should be stated fairly prominently in the 
  > docs.

  > Duncan Murdoch
  >> All instances of this feature reported so far involved commands that
  >> produced random numbers and the poster was surprised that the output
  >> in the text and the figures differed (and that the two figures were
  >> different).
  >> In your case the first execution of the code assigns the names to
  >> partytotal, sorts partytotal and produces the data.  On the next
  >> execution, when the picture is produced, partytotal is already sorted
  >> but you reassign the names.  Then the partytotal is sorted again and
  >> the plot is produced.  But that re-assigning of names lead to the
  >> disconnect between values and names.
  >> Hope this helps.
  >> Cheers,
  >> Berwin
  >> ========================== Full address ============================
  >> Berwin A Turlach                      Tel.: +61 (8) 6488 3338 (secr)   
  >> School of Mathematics and Statistics        +61 (8) 6488 3383 (self)      
  >> The University of Western Australia   FAX : +61 (8) 6488 1028
  >> 35 Stirling Highway                   
  >> Crawley WA 6009                e-mail: berwin at maths.uwa.edu.au
  >> Australia                        http://www.maths.uwa.edu.au/~berwin

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