[R] plot.Map with pattern instead of colors

[Arne Henningsen]

Hi,

I am plotting shapefiles with plot.Map (package maptools). So far I use 
different colors for the shapes depending on the a value that belongs to the 
shape. Now, I need to produce maps only in black, gray and white for 
publication. Is it possible to fill shapes with pattern (e.g. hatched) 
instead of colors? 

Details of a simplified example:
I want to show the percentage change of a variable in a map:
e.g. following levels
a) >+10
b) +5% to +10%
c) -5% to +5%
d) -10% to -5%
e) <-10%

Now I have following colors
a) "red"
b) "orange"
c) "white"
d) "greenyellow"
e) "green3" 

Printing this on a monochrome printer is - of course - stupid, because levels 
a) and e) as well as b) and d) have approximately the same grayscale. 
I could fill a) = black and e) = white, and everything inbetween with an 
appropriate grayscale, but I prefer to have areas with no change to appear 
white rather than medium gray. Therefore, I thought of doing following:
a) black
b) gray
c) white
d) hatched with thin lines
e) hatched with thick lines (or double-hatched)

Any hints and ideas are welcome!
(BTW: I use R 1.9.1 on SuSE Linux 9.0)

Thanks,
Arne

-- 
Arne Henningsen
Department of Agricultural Economics
University of Kiel
Olshausenstr. 40
D-24098 Kiel (Germany)
Tel: +49-431-880 4445
Fax: +49-431-880 1397
ahenningsen at agric-econ.uni-kiel.de
http://www.uni-kiel.de/agrarpol/ahenningsen/