[R] How to quieten axis() for Sweave: avoid echoing NULL?

[Peter Dalgaard]

Andrew Robinson <andrewr at uidaho.edu> writes:

> Dear R-community,
> 
> I'm using Sweave to produce reports.  The reports require the "axis"
> command.  When I run axis the program returns NULL as well as creating
> the axis.  
> 
> > plot(1:4, rnorm(4), axes=FALSE)
> > axis(1, 1:4, LETTERS[1:4])
> NULL
> >
> 
> So, my Sweave tex files have 
> 
> \begin{Schunk}
> \begin{Soutput}
> NULL
> \end{Soutput}
> \end{Schunk}
> 
> in front of each graphic that requires axis.  I can easily find them
> and remove them, but I was wondering: is it something I can avoid?  Or
> am I doing something foolish and obvious?

I think this qualifies as a bug along with similar issues with
title(), text(), and mtext(). They all end with .Internal calls
producing NULL. Once upon a time, they did so invisibly, but somehow
this changed.

The simple workaround is to wrap the call in invisible().

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907