[R] Maps and plotting

Roger Bivand Roger.Bivand at nhh.no
Wed Oct 13 20:40:48 CEST 2004

On Wed, 13 Oct 2004, 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.
> Are there any packages out there that can aid me in doing this?

See R 2.0.0 NEWS: 

    o	It is now possible to specify colours with a full alpha
	transparency channel via the new 'alpha' argument to the
	rgb() and hsv() functions, or as a string of the form "#RRGGBBAA".

	NOTE: most devices draw nothing if a colour is not opaque,
	but PDF and Quartz devices will render semitransparent colours.

	A new argument 'alpha' to the function col2rgb()
	provides the ability to return the alpha component of
	colours (as well as the red, green, and blue components).

and output on the PDF device - works very nicely with the standard 
points() function and other graphics functions. For on-screen rendering, 
it looks as though only the Quartz device will do this, but PDF is 

> Thanks,
> Shawn Way, PE
> Engineering Manager
> ________________________________
> "Policies are many, Principles are few, Policies will change, Principles
> never do." 
> -John C. Maxwell
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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no

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