Hi Steve,
If you read your netCDF files into R you end up with sp-classes which
can be displayed using spplot. But you do not seem to use rgdal.
If you can make a data.frame with the x, y and z coordinates this can
quite easily be transformed into an sp-class:
library(sp)
dat = data.frame(x = UTMx, y = UTMy, z = wat.data2001q1,,i])
coordinates(dat) = ~x+y # "tell" spplot what the names of the columns
with the x and y coordinates are
gridded(dat) = TRUE # make clear it is a grid
spplot(dat)
For more details see the documentation for the sp-package, especially
spplot. These kinds of questions are more suitable for the r-sig-geo
mailing list and not the general r-help list.
hope this helps,
Paul
[EMAIL PROTECTED] schreef:
Hello
I'm working with a large hydrological data set stored in a netCDF format.
The file stores x and y coordinates in the UTM projected coordinate system,
yet when I use image to graphically display the z variable, the image is
distorted in the sense that it does not plot the map in the correct spatial
organization.
I'm wondering if I need to define the projection of the netCDF file with
rgdal or proj4 routines first before I send it to the graphics device.
Defining the projection is not needed
My code is as follows:
q1_2001 <- open.ncdf("H:\\SKF_DESKTOP FILES\\My
Documents\\EDEN\\EDEN\\Surfaces\\2000_q1.nc", readunlimi=FALSE) #opens ncdf
file for reading
wat.data2000q1 <- get.var.ncdf(q1_2001, verbose=FALSE ) # gets the real
information
# GENERAL EXAMINATION OF HEADER DATA in the wat.data file
day <- get.var.ncdf(q1_2001, "time") # length(day) 91 days in quarter
UTMx <- get.var.ncdf(q1_2001, "x") # columns (eastings) # should
return 405
UTMy <- get.var.ncdf(q1_2001, "y") # rows (northings) #
should return 287
# plot first 91 days (3 months of the year)
for(i in 1:91) {
!is.na( image(UTMx, UTMy, z = wat.data2001q1[,,i], col=brewer.pal(8,
"YlGnBu"),
axes=T, pty="s", ylab="UTM Northing", xlab="UTM Easting",
main = "First Quater 2001") )
}
As I indicated above the map is displayed on the graphics device. However
the orientation is distorted pulling the x axis to wide and the y axis too
tall. How can I set the graphics device to know the orientation and
scaling (if these are the correct terms) in order to display this map
correctly?
All insights will be greatly appreciated.
Thanks
Steve
Steve Friedman Ph. D.
Spatial Statistical Analyst
Everglades and Dry Tortugas National Park
950 N Krome Ave (3rd Floor)
Homestead, Florida 33034
Office (305) 224 - 4282
[EMAIL PROTECTED]
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--
Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
Heidelberglaan 2
P.O. Box 80.115
3508 TC Utrecht
Phone: +31302535773
Fax: +31302531145
http://intamap.geo.uu.nl/~paul
______________________________________________
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