[Rd] removing last piece of grid graphical output with grid.remove

[Paul Murrell]

Hi


Erik Iverson wrote:
> Hello -
> 
> If I create multiple pieces of output in grid, and use grid.remove() to
> try to remove the output from the graphics device, I cannot seem to
> remove the final piece of output from the device until I 'refresh' the 
> graphics device by giving it focus.  The function grid.remove() does 
> appear to remove the grob from the display list, however.
> 
> I noticed this when the example on page 200-201 in Paul Murrell's R 
> Graphics book did not work as expected when using 
> grid.remove("circles").  Can anyone replicate this?


I've seen this type of behaviour on X11 before, but I think it is
specific to that device (e.g., you get the "right" behaviour on Windows).

I have not yet attempted to seek out the source of the X11 problem.

Paul


> ## Example
> library(grid)
> 
> ## Create two circles
> grid.circle(name = "redcircle",  r = .20, gp = gpar(col = "red"))
> grid.circle(name = "bluecircle", r = .25, gp = gpar(col = "blue"))
> 
> ## removes the blue circle
> grid.remove("bluecircle")
> 
> ## the red circle will be deleted from the grid display list, but
> ## the graphics device will still show it until I 'refresh' the
> ## device by giving it focus via mouse or alt+tab, or producing
> ## more grid output
> grid.remove("redcircle") ## still on my X11 device!
> 
> ## more grid output
> grid.text("Now the circle is gone!", name = "txt")
> 
> ## But I can't get rid of this text on the device
> ## until I refresh device or do another grid call
> grid.remove("txt")  ## still on my X1 device!
> 
> 
>  > sessionInfo()
> R version 2.6.2 (2008-02-08)
> i686-pc-linux-gnu
> 
> locale:
> LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=en_US.UTF-8;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
> 
> attached base packages:
> [1] grid      stats     graphics  grDevices utils     datasets  methods
> [8] base
> 
> ______________________________________________
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-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/