[R] Maps and plotting
Prof Brian Ripley
ripley at stats.ox.ac.uk
Thu Oct 14 13:04:59 CEST 2004
On Thu, 14 Oct 2004, Barry Rowlingson wrote:
> Shawn Way wrote:
> > At our facility we have multiple sample points that are sampled on any
> > given day. What I would like to do is create a map of the facility with
> > the sample points (and point labels) and when we have out of
> > specification results, place a transparent dot over the area on the map.
> > As the number of OOS results builds up, I envision the dot getting
> > darker.
> Over what timescale? This sounds like it could be an interactive,
> real-time on-line monitoring thing. Is it?
> In which case R's graphics devices might not be good enough, and you'd
> be better off using a TclTk graphics canvas.
> library(tcltk) and read the docs!
> Another idea, if all you are doing is updating a daily image, would be
> to use a language like Python, and the Python Imaging Library (PIL) to
> draw pretty graphs.
> I've done something similar that produces daily maps of disease
> incidence, but I used different size and colour circles and not
> transparency, so I just used base R graphics and produced a PNG file. If
> I wanted transparency I'd probably use Python/PIL, which can handle
> alpha channels.
I think this may mean *translucent* dots. R has been able to do
transparent dots for a very long time, but PNG cannot handle
translucency. On devices (e.g. pdf) which can, you can do this as of R
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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