importing adf file to R using RArcInfo / converting adf file to R friendly format
Harry,
I have been able to reproduce your error and it seems that the problem
is that there is not enough memory to load your data. Furthermore, I am
not sure whether RArcInfo can handle this sort of gridded data. I
believe that your data is an Arc/Info Binary Grid, which can be read
with package rgdal:
library(rgdal)
dpath<-"/home/vrubio/tmp/GLiPHAmaps/global/poultry/totcor/glbpod1t0503m/hdr.adf"
x <- new("GDALReadOnlyDataset", dpath)
getDriver(x)
getDriverLongName(getDriver(x))
library(RColorBrewer)
xx<-asSGDF_GROD(x, output.dim=c(200, 200))
spplot(xx, "band1",
at=c(0, 10, 50, 100, 200, 500, 1000, 2500, max(xx$band1,
na.rm=TRUE)),
col.regions=brewer.pal(8,"Oranges") )
If you require a higher resolution try to increase the values of
output.dim=c(200, 200) but be careful because it can take a lot of
memory.
Hope this helps,
Virgilio
On Tue, 2008-09-02 at 12:35 -0700, Harry Kim wrote:
Dear R-sig-geoers
I need some help on importing adf file--ArcGIS coverage file
which is no longer supported--into R and was hoping if I could get any
input from you. I've searched the forum and came across a package
named "RArcInfo".
It has functions to read and plot the ArcGIS coverage files in R.
I obtained the data from
http://www.fao.org/geonetwork/srv/en/metadata.show?id=12720
The direct link to the data set is
http://www.fao.org/geonetwork/srv/en/resources.get?id=12720&fname=glbpototcor.zip&access=private
and this is what it is supposed to look like
http://www.fao.org/geonetwork/srv/en/resources.get?access=public&id=12720&fname=glbpod1t0503m.gif
Here is what I did so far:
#set the path
datadir=getwd()
coveragedir= "C:/Users/Harry/Desktop/poultry/glbpod1t0503m/"
infodir= "C:/Users/Harry/Desktop/poultry/info/"
#obtain table and coverage names
tablenames<-get.tablenames(infodir)
covnames<-get.namesofcoverages(datadir)
arc=get.arcdata(datadir, covnames, filename="w001001x.adf")
The arc file is read into R and I can even plot it but when I try
the file that I am actually interested in analyzing (w001001.adf), R
crashes. I am assuming that the size of the file (100 mb) is too much
to handle and it breaks.
So I would like to see if it is possible to convert this ArcGIS
coverage file into more managable format in R. Are there any suitable
options? My final aim is to get the density values associated with the
coordinates in the world. I am aware that I can convert the coverage
file to E00 format but I've searched on the internet how I can use
this in R, and so far had no luck finding much of valuable
information.
Thank you so much
Harry
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