[R] help with data presentation (cartograms)

[Roger Bivand]

On Wed, 29 Aug 2001 kfast at poczta.onet.pl wrote:

> I want to use a distorted political map of the world with certain
> countries increased in size according to a certain variable (an idea
> similar to the homunculi usually found in psychology textbooks) to
> demonstrate the coverage of particular countries in a news service.
> Does anyone have any idea of how to approach this? I don't think there
> is any software or anything that could do it, but I would be more than
> happy to hear a couple of ideas/intuitions as to how to tackle this.
> 
Your are looking for cartograms, see for example:

http://www.geog.qmw.ac.uk/hgis/conference/cartogram.html

and look for work by Danny Dorling. Another site is:

http://www-viz.tamu.edu/faculty/house/cartograms/index.html.

Dorling cartograms are mostly bubbles, Kocmoud/House deformed polygons.
There is a Java applet at:
http://www.geog.leeds.ac.uk/pgrads/j.macgill/java/Cartogram.html, and the
details are in: Dorling, Daniel (1996): Area Cartograms: Their Use and
Creation, Concepts and Techniques in Modern Geography (CATMOG), 59. The
complicated issue is to jitter the centres of the circular symbols so that
they are close to the point representing the original object location,
their area is proportional to the chosen weighting variable (here coverage
in the news service), they do not overlap; they are then filled to
represent the variable being visualized.

Roger

-- 
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
and: Department of Geography and Regional Development, University of
Gdansk, al. Mar. J. Pilsudskiego 46, PL-81 378 Gdynia, Poland.


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