Hello! My name is Eibe Frank.
I'm with the Department of Computer Science
at the University of Waikato, the home of
Weka, and it is my job to tell you a bit about
how to use the statistical computing environment
R from Weka.
So, let's get started.
Because R is implemented in a different programming
language than Weka, which is implemented in
Java, getting things setup so that Weka can
use R is a little bit tricky, but we will
go through the steps in this first video.
The following assumes that you're using 64-bit
Windows, 64-bit R, and 64-bit Java.
You can also do the same if you use 32-bit
versions of everything.
Furthermore, we'll assume that you have administrator
access on your computer, and we assume that
you have a direct connection to the internet.
All right.
The first thing we need to do is download
R and install it.
Download R.
Download R-3.2.2 for Windows, that's the current
version, and now we should download it by
clicking on this download link here, but to
save some time, I've already downloaded R,
and we can just install it from here.
Okay.
We accept this.
We run the installer.
We want English as the language, and we just
accept the license, which is the same as the
one used for Weka.
Accept the default install location.
Now, because I want to use 64-bit R, I unselect
32-bit files here, and then I just go with
the standard setup.
I also want to create a Start menu folder,
and we accept the defaults here, as well.
Okay, finished!
Now we have installed R.
The first thing we should do is install a
particular package in R that is necessary
for R to be able to communicate with Java, the programming environment that Weka is implemented in.
We start R from the shortcut, and we get the
R console, where we can enter text commands.
This is the standard way to interact with
R, because R is really a programming language.
We type in 'install.packages("rJava")'.
We want to install this in the personal library,
and we want to create this library.
Because I'm in New Zealand, I want to download
from a New Zealand computer, a New Zealand
server, so I click on New Zealand here.
Okay, rJava has been installed successfully.
We just close this, and now what we need to
do next is set up some environment variables.
We search for "variables" using the Windows
search functionality, and then we click the
item "Edit environment variables for you account".
There are already some environment variables
there, we need to add some new ones.
We click on New to enter a new variable.
This new variable is called R_HOME, and the
variable value is the location of the R distribution.
To find this, we right click on the R shortcut
and we go in Properties, and now we have the
location of the R distribution here.
It's the path to the directory containing
the R binaries.
We select everything up to the bin folder.
Then we paste it here.
That's the R_HOME variable.
The next variable we need to insert is the
R_LIBS_USER variable, which determines the
location of the user libraries that R installs.
Now, we've already installed one user library,
namely the rJava library, so we just need
to find it and put the location of this library
here.
Let's just use the Windows search functionality
again to search for rJava.
It's a file folder.
Now we just go up one level.
This is the folder containing all of the user
libraries for R, so we right click on this
text field and we select "Copy address as
text" to copy this path.
Then we go back to our form to enter the variable
value for our user variable.
We right click and we paste it in.
We're almost done now.
The last thing we need to do is modify the
path environment variable to include the directory
containing the R executable.
We select this PATH environment variable and
click on the Edit button, and at the end,
we add a semicolon, and then we use the location
of the R executable.
In this case, we actually use this bit of
the path for the R executable.
Okay. This should be it.
We just go OK here.
Now what we need to do is install the R plugin
package for Weka, which is Weka's interface for R.
We start Weka, and we go to the Package manager.
It just refreshes the package cache at the start.
Once it's done that and popped up the window,
we can select the R plugin.
R plugin is here.
We choose the Install button.
Okay.
Right.
There's quite a bit of information here in
this window, install information for the R plugin.
This is about setting the environment variables
that we just set before, so we just click
OK here.
Now, it takes a little while for R to be downloaded
and installed, but it doesn't take too long.
It actually also installs an additional R
library, the Java JD library for R, which
makes it possible to output R plots in Java.
Okay, now it's finished.
You just need to restart Weka.
We close this, close this.
Start Weka again.
Okay, and now when we start the Explorer,
we can load in some data.
In this case, just go to the Program Files
folder, and then the Weka folder, and then
there's a data folder.
We load in the iris data.
Now we can go to the R console, which is a
new tab here that comes as part of the R plugin
package, which provides us with a console
for R implemented in Java.
This console allows us to address the data
that we've loaded in the Preprocess panel
using the name "rdata".
We can go "plot(rdata)", and this will give
us a plot of the iris data generated by R.
Okay, that's it for this video.
We'll look at the R console a bit more next time.
See you later!
