[R] grid.edit() for ggplot2

[baptiste auguie]

Perfect, thank you!

Thanks also to Gabor G. for the links.

baptiste

On 2 Jun 2009, at 01:30, Paul Murrell wrote:

> Hi
>
>
> baptiste auguie wrote:
>> Dear all,
>>
>>
>> I'm trying to access and modify grobs in a ggplot2 plot. The basic  
>> idea
>> for raw Grid objects I understand from Paul Murrell's R graphics  
>> book,
>> or this page of examples,
>>
>> http://www.stat.auckland.ac.nz/~paul/grid/copygrob/copygrobs.R
>>
>> However I can't figure out how to apply this to a ggplot (basically I
>> don't know how to write a syntactically correct gPath),
>>
>>
>> p <- # minimal example
>> qplot(0,0)+ annotate("text",0,0,label="test")
>>
>> g <- # store the plot as a grob
>> ggplotGrob(p)
>>
>> # structure of the grob
>> grid.ls(g) # rather large!
>>
>> # find a particular grob in the gTree
>> getGrob(g,"texts", grep = T)
>>
>>
>> # next step, modify, say, the colour of these grobs
>> grid.edit() # what do I put in here?
>
>
> (Ignoring whether this is the most ggplot-ish way to achieve the end
> result ...)
>
> Let's take a closer look at the part of the grob (gTree) that you have
> selected ...
>
>> grid.ls(getGrob(g,"texts", grep = T))
> texts.gTree.5
>   GRID.text.3
>
> ... (the "5" and the "3" in those names are likely to be different for
> you).  This is a gTree with one child, which is a text grob.  I don't
> know much about how the "texts" gTree works, so it's not clear how I
> should modify that to influence the text grob, but I do know that I  
> can
> modify the 'gp' component of the text grob.  For example ...
>
>> grid.edit("GRID.text.3", gp=gpar(col="red"))
>
> ... and if I wanted to be SURE that I was getting the text grob  
> beneath
> that "texts" gTree, then I could use a gPath like this ...
>
>> grid.edit(gPath("texts.gTree.5", "GRID.text.3"), gp=gpar(col="blue"))
>
> ... and if I wanted to use code that had a better chance of working in
> another session (when the "5" and "3" name suffixes are likely to be
> different), I could use something like ...
>
>> grid.edit(gPath("texts.gTree", "GRID.text"), grep=TRUE,
>             gp=gpar(col="pink"))
>
> ... does that give you what you were looking for ?
>
> Paul
>
>
>> Thanks for any piece of advice,
>>
>> baptiste
>>
>> ______________________________________________
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>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
> -- 
> 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/

_____________________________

Baptiste Auguié

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag