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
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> 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/