From atp at piskorski.com  Thu Apr 24 22:13:09 2014
From: atp at piskorski.com (Andrew Piskorski)
Date: Thu, 24 Apr 2014 16:13:09 -0400
Subject: [Rd] palette() can hang and fail due to X11
Message-ID: <20140424201308.GA22592@piskorski.com>

For many years, when my R process starts up I've been automatically
setting my preferred default plot colors, basically like so:

  my.colors <-
     c("black" ,"red" ,"gold" ,"sky blue" ,"green" ,"blue" ,"orange"
       ,"grey" ,"hot pink" ,"brown" ,"sea green" ,"cyan" ,"purple" ,"tomato1")
  require("grDevices")
  palette(my.colors)

That seemed to work reliably in all 2.x versions of R, regardless of
whether my R was interactive or not, or if my Linux, ssh, and screen
environment had X-Windows properly set up or not.  It Just Worked.

However, now in R 3.1.0 Patched (2014-04-15 r65398, on Linux),
depending on whether I have a good X-Windows connection or not it can
fail like so:

  Error in .External2(C_X11, d$display, d$width, d$height, d$pointsize,  :  
    unable to start device X11 

Simply wrapping the palette() call in try() of course helps keep that
error from breaking the rest of my R start up.  However, occasionally
the call to palette() will hang for perhaps a minute, unexpectedly
locking up my R process until it finishes whatever it was doing.

But, all I want to do here is set my default colors to the length 14
vector above, which seems like something that SHOULD be simple...  Is
there some way for me to reliably do that WITHOUT invoking all this
extra X11 device machinery?

The relevant C code appears to be "palette" in
"src/library/grDevices/src/colors.c" and "do_dotcallgr" for
.Call.graphics in "src/main/dotcode.c", but I don't understand what
part is triggering the additional complex behavior, nor how I should
avoid it.

Any advice on how I should handle this robustly?  (Thanks!)

-- 
Andrew Piskorski <atp at piskorski.com>



[Rd] palette() can hang and fail due to X11
Andrew Piskorski