Re: [R] childNames for xaxis grob (grid package)

From: Paul Murrell <p.murrell_at_auckland.ac.nz>
Date: Thu, 10 Jul 2008 14:39:58 +1200

Hi

Tobias Verbeke wrote:
> Dear list,
>
> Can someone explain why the childNames below
> gives
>
> character(0)
>
> instead of the (canonical) names of the children grobs
> of the xaxis gTree ?
>
> [1] "major" "ticks" "labels"

The problem is that you xaxis has an 'at' component of NULL, which means that the axis calculates its tick marks on-the-fly when it comes time to draw (it has to ask the current viewport what the current scale is).

This means that there are no grobs representing the major, ticks, and labels stored with the xaxis grob on the display list. These are generated just to draw then thrown away.

If you want to modify the look of the grobs that are drawn (then thrown away), you can use the 'edits' component of the xaxis. This provides an edit that will be applied whenever the children are created for drawing.

Simple example (assuming your code below has been run) ...

 grid.edit("xa", edits=gEdit("labels", rot=45))

Paul

> Many thanks in advance,
> Tobias
>
> ### minimal example code ###
>
> library(grid)
> pushViewport(plotViewport(c(5,4,4,2)))
> pushViewport(dataViewport(1:5, 1:5))
> grid.points(1:5, 1:5)
> grid.xaxis(name = "xa")
> grid.get("xa")
> childNames(grid.get("xa"))
>
> ### sessionInfo() ###
>
> > sessionInfo()
> R version 2.7.1 (2008-06-23)
> i486-pc-linux-gnu
>
> locale:
> en_US.UTF-8
>
> attached base packages:
> [1] grid stats graphics grDevices utils datasets methods
> [8] base
>
> ______________________________________________
> 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/

______________________________________________
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.
Received on Thu 10 Jul 2008 - 04:54:13 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Thu 10 Jul 2008 - 08:31:47 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive