About 6 months ago, I wrote a package for the R programming language called rNOMADS. It interfaces with the National Oceanic and Atmospheric Association’s Operational Archive and Distribution System (NOMADS), comprising everything from global weather forecast models, to high resolution regional models, to wave and sea ice models. rNOMADS uses R to download requested data from the NOMADS servers and uses an external program called wgrib2 to read the data files. This allows R users to make some spectacular pictures (see below) but I also hope that it will lead to greater availability of these valuable resources to data analysts all over the world. Already, rNOMADS is being used in an online sailboat racing game and to get data for predicting solar and wind energy output. However, rNOMADS can be a bit of a challenge to install. Below the picture, I’ll outline an installation I recently did on an Ubuntu computer. Other Linux should be similar. To my knowledge, Windows users will have to use Cygwin. I am not sure about Mac.
The first step is to make sure R is configured correctly. You can skip the reinstallation (step 2) if need be, but I recommend getting r-base-dev anyway for all the libraries it has.
apt-get install r-base-dev
apt-get build-dep r-base
Then, I build R from the source. You can skip this method if you’ve already done this.
You can download the latest version (as of March 2014) here.
Navigate to the file and type:
tar -xvf R-3.0.3.tar.gz
Now we get dependencies for specific packages that rNOMADS requires.
apt-get install libxml2-dev
apt-get install libcurl4-openssl-dev
apt-get install libboost-dev
tar -xvf wgrib2.tgz
mv wgrib2/ /usr/local
mv wgrib.tar wgrib
tar -xvf wgrib.tar
mv * /usr/local/wgrib
add “/usr/local/wgrib2″ and “/usr/local/wgrib” to the end of the PATH variable, then close /etc/environment and close the superuser terminal.
Now we install rNOMADS and another package called GEOmap so that we can build and test the example vignette.
Now we are in the R interpreter, as root. Type:
If everything went well, you now have rNOMADS! Test rNOMADS (and learn how it works) by building the example vignette. First, download the source here and navigate to the saved file. Then, type:
R CMD Sweave rNOMADS_examples.Rnw
This should create a PDF file called “rNOMADS_examples.pdf” with code and images. It should look similar to this one.