Message-ID: <Prayer.1.0.12.0709031915160.20358@amos.qub.ac.uk>
Date: 2007-09-03T19:15:16Z
From: Michal Gallay
Subject: Image colours based on certain values
In-Reply-To: <Pine.LNX.4.58.0709031336470.30656@dalmore.c3sl.ufpr.br>
Dear R Spatial Users,
I have many DEM ASCII grid files and have produced maps(images) via
image(). The maps display e.g. slope angle, profile curvature for one area,
but calculated via different methods.
I have searched R help, the R group, but I couldn't find out how to make R
use certain colours for certain image values, in order to be able to
compare the maps, for instance to have the same color for 0 curvature
values, no matter what is the range of values.
If it helps, the following is applied in a 'for' loop for 20 files:
raster.values <- read.asciigrid(fname=Files[i], as.image = FALSE,
plot.image = FALSE, colname = Files[i])
min.val <- min(raster.values at data, na.rm=TRUE)
max.val <- max(raster.values at data, na.rm=TRUE)
image(raster.values, zlim=c(min.val,max.val), col=bpy.colors(255,
cutoff.tails = 0.1), axes=TRUE)
I appreciate and thank you for help.
Michal
--
Michal Gallay
Postgraduate Research Student
School of Geography, Archaeology and Palaeoecology
Queen's University
Belfast BT7 1NN
Northern Ireland
Tel: +44(0)2890 273929
Fax: +44(0)2890 973212
email: mgallay01 at qub.ac.uk
www: www.qub.ac.uk/geog