22 Teaching Tricks
There are several tricks that are of use to teachers of statistics
in the lab. Here are a few.
Exchanging data with students
- The task of getting data and
functions to the students so that they may easily use it in the lab
is really quite simple using R thanks to some handy commands
provided by R's developers.
The scenario is you, the instructor, have created some functions and
have data sets that will save your students from typing or something
else. You want to get them from your computer to the students. Thus
there are two things: saving and reading in.
Saving your work
- The package mechanism for R can be used
for this and should be if you have major amounts of work. However,
if you have a lab sessions worth of data and functions you may not
want to go to the trouble. Instead, you can save the commands and data
using dump into one file.
For example, suppose you have a function
really.convenient.function and a dataset
too.large.to.type and you want to save these in a file to
distribute to your students. This can be done with
> dump( c("really.convenient.function","too.large.to.type"),
file = "file-for-my-students.R")
This creates the file with your given file name which can later be
"sourced" into your student's R session.
- Distributing your work
- You probably can put your file on
floppies and distribute to your students to read in during a lab
session using source.
This is very easy, but not the best
solution if you have access to the internet.
In this case, you can place your file on a web site and then have
your students "source" the file using a url for the file. To be
specific, suppose you put your file so that its web address (url)
is http://www.simpleR.edu/file-for-my-students.R. Then,
students can read this into their session using the following command
That's it. Make sure your students know how important punctuation
is. If you have a really long base for your url's, you might
suggest to students to define this as a variable so they don't
need to type it. Then the paste command can be used. For
> baseurl = "http://www.simpleR.edu/reallylongbaseurl"
- Students saving their work
- If a student wishes to save their
working session they can easily do so.
If a student is always assigned to the same machine or is working
with the same account, then when R quits it stores a copy of its
session in a file called .Rdata in the current directory. If R is
started from that directory it will automatically load this in.
If the students move about and want to take a copy of their work
with them, the underlying mechanism is available to them via the
function save.image(). For example, if the student is on the
windows platform, then the following should save the image to a file
on the ``a'' drive in a file called ``rdata.Rd''
To load the session back in, the load command is used. This
command will restore from the floppy
As well, the menus in windows allow this to be done with a mouse.
Copyright © John Verzani, 2001-2. All rights reserved.