The tcltk package now comes bundled with R, so you may not need to
install anything if you just want to use the basic Tk widgets. Most of the examples
at this website should work simply by pasting them into an R session.
However, you will not be able to run the drop-down combo box example or the TkTable example without a separate installtion, because they require additional packages which are distributed with ActiveTcl. For R 1.6.x, it was necessary to download Active Tcl 8.3.x, but for R 1.7.0, the version of ActiveTcl you should use (if you want the extra packages) is 8.4.x.
Once you have installed ActiveTcl and made a note of which directory you installed it
in, you need to make sure that the Tcl\bin directory (e.g. C:\Tcl\bin) containing the
dynamic librarys (dlls) is included in your Path environment variable. You also need
create a new environment variable, TCL_LIBRARY (if it doesn't already exist), and set
its value to the directory containing the tcl8.x library (e.g. C:\Tcl\lib\tcl8.4). Finally,
you need to create a new environment variable, MY_TCLTK (if it doesn't already exist),
and set it to a non-empty value (e.g. "yes"). Once this is complete, you should not
only be able to load the tcltk package in R with require(tcltk),
but you should also be able to use additional widgets not available in the bundled R
installation, e.g. to use a drop-down combo box, you would need to type
tclRequire("Iwidgets") after typing require(tcltk).
One common method for setting environment variables in Windows 2000 will be illustrated below with screenshots. But firstly, Henrik "R.oo" Bengtsson has kindly pointed out that there are other ways to set environment variables for use in R for Windows, as described in Brian Ripley's R for Windows FAQ, which can be found in the Help Pull-Down Menu of RGui. (See the section, "How do I set environment variables?".)
One method involves modifying the short-cut to R. Another way is to create a .Renviron
file to define your environment variables relevant to R, which also works in Unix. If your
directory name includes spaces, (e.g. C:\Program Files\Tcl), then you will
need to put quotes around the directory name or put backslashes before the spaces. See Brian Ripley's
R for Windows FAQ for more details.
The usual method for setting environment variables in Windows 2000 is shown below. (Alternatively you can go to the Control Panel and then double-click on "System". The latter method may be more portable to other versions of Windows.)
Right-click on the My Computer icon and select Properties.
Click on the Advanced tab of the Properties dialog.
Click on the Environment Variables button.
Now you can create new environment variables, and also edit existing environment variables, e.g. Path.
To set environment variables in Windowx XP, open the system applet from the Conrol Panel, click the Advanced tab and do the same thing as above for Windows 2000.
To set environment variables in Windowx ME, you can use the System Configuration Utility (under Programs, Accessories, System Tools on the Start menu).