Dear Patrick & Renaud,
Categorical maps are one of the issues we have looked at in a new
package 'rworldmap' that we've been developing. Coincidentally I
submitted the first version to Cran for consideration yesterday.
The package and source can currently be downloaded from :
http://code.google.com/p/rworld/downloads/list
With a SpatialGridDataFrame containing categorical data, default
plotting should be as easy as :
library(rworldmap)
mapGriddedData(sGDF, catMethod='categorical')
#colours can be changed by e.g.
mapGriddedData(sGDF, catMethod='categorical',
colourPalette=c('red','white','blue'))
#or
mapGriddedData(sGDF, catMethod='categorical',
colourPalette=c("#E5F5E0","#A1D99B","#31A354"))
A default legend is added and there are options for modifying it.
The package concentrates on displaying global data, either gridded or
referenced by country.
I'll be interested to hear any feedback that you or others have,
This builds particularly on the packages sp, maptools and fields, so
thanks go out to all those that have contributed to those packages.
Happy new year,
Andy
Dr Andy South
Leader Spatial Information, Fisheries
Cefas, Pakefield Road, Lowestoft , Suffolk, NR33 0HT, UK
Tel: +44 (0)1502 524213
Fax: +44 (0)1502 513865
www.cefas.co.uk
Message: 1
Date: Thu, 31 Dec 2009 12:07:03 +0100
From: Renaud Lancelot <renaud.lancelot at cirad.fr>
Subject: Re: [R-sig-Geo] color category SpatialGridDataFrame
SpatialPolygonsDataFrame Corine Land Cover Global Land Cover
2000
To: patrick.giraudoux at univ-fcomte.fr
Cc: r-sig-geo at stat.math.ethz.ch
Message-ID: <4B3C85D7.7050600 at cirad.fr>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Dear Patrick,
I recently met this issue. I finally used image() on the
SpatialGridDataFrame, defining the appropriate colors using the col
argument (?tonnant, non ;-)). I have defined the legend using legend(),
and I used split.screen() to arrange the plots. If you wish, I can send
you the whole stuff (data and code) in a private message (huge
datasets).
Renaud
Patrick Giraudoux a ?crit :
Dear all,
I am wondering what is the safest way to handle colors when
SpatialGridDataFrame data are categories. spplot() or image() are
extremely convenient when attributes are continuous variables or so
(eg altitude, rainfall, etc...), but the colorRamp() system and the
col.regions, col arguments, though extremely powerful in other cases,
is not really adapted to category data such as Corine LandCover or
Global Land Cover 2000 codes. Thus to link pixels to the right color
may be quite tedious (however I may have missed something...).
One option I though about was to change raster into shapefile (or
SpatialGrid into SpatialPolygons objects), but again the straight way
to get right colors is not evident.
Any idea ?
Patrick
--
Renaud Lancelot
EDEN Project, coordinator
http://www.eden-fp6project.net/
<< EDEN International Conference, Montpellier, 10-12 May 2010 >>
<< http://international-conference2010.eden-fp6project.net/ >>
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