[R] ggplot 2 - editing in the "panel_1_1" viewport

[Paul Murrell]

Hi


Pedro Barros wrote:
> Hi Paul,
> Thanks for the tips. I am using ggplot indeed, but I am trying to "drill
> down", and extract several grobs, most of which are gTrees or frames. Until
> now, I have more or less managed, but I am having difficulties because I
> would like to get at the gTrees that are in each cell of a frame. From a
> grid.ls() printout, I managed to discover that these are cellGrobs, but I
> cannot find any documentation for these.
> So, the more straightforward question would be "If I have a frameGrob, with
> several children (in different levels), how can I get the grob that is in
> row 2, column 4?". I assume there is a way, but I could not find out how...


There is no "system" to the naming of cellGrobs because cells can occupy
any subset of the cells of a frame, including overlapping each other and
more than one cellGrob in the same cell (i.e., I could think of no
simple, completely general naming scheme).  However, all is hopefully
not lost because you can hopefully apply a naming scheme to the gTrees
that you are placing within the cells and you can make use of that (?).
 You may need to make use of the 'grep' argument of grid.get() et al to
specify a gPath through a cellGrob that you do not know the *exact* name
for.

Paul


> Thanks a lot for the great package, BTW!
> Pedro
> 
> Paul Murrell wrote:
>> Hi
>>
>>
>> Pedro Barros wrote:
>>> Hi All,
>>>
>>> I am trying to find out how to access the components of a ggplot plot,
>>> and I
>>> found this reply from Paul Murrel
>>> http://www.nabble.com/navigating-ggplot-viewports-tt14826352.html#a15056223.
>>> I tried it, and it works.
>>> However, I am trying to develop some functions that will do the drawing
>>> "automatically", and usually I will not know the full name of the grob
>>> that
>>> has the layout vp, like "plot.gtree.76". Is there a way that I can repeat
>>> the same process, without going through the grid.ls step?
>>
>> Being able to divine the names of grobs (and viewports) is dependent on
>> the system being used to name the grobs/viewports.  One approach, taken
>> in lattice for viewports, is to provide a function, e.g.,
>> trellis.vpname(), that builds a name from salient bits of information,
>> e.g., panel numbers.  Another important source of information is
>> documentation of the naming scheme, e.g., for ggplot2, Hadley's
>> http://had.co.nz/ggplot2/book/grid.pdf
>>
>> Paul
>>
>>
>>> Thanks,
>>> Pedro
>> -- 
>> 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/
>>
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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/