Graphing routines in Tcl/Tk

Question

I want to do simple graphing routines in Tcl/Tk like scatter plot, x-y plot, histograms. I am using Tcl/Tk 8.5.7. I found in Tcler's wiki that there are few options such as BLT which is not supported in Tcl/Tk 8.5+

Is there any Tcl/Tk interface to gnuplot or any widget to accomplish graphing?

Please let me know about the choices for graphing routines in Tcl/Tk.

Answer 1

Gnuplot can indeed produce output that Tcl/Tk can consume. This page on the Tcler's Wiki describes how (though with some extra complexity because it is doing animations). Here's a simplified version:

package require Tk
eval [exec gnuplot << "
    set term tk
    plot x*x
"]
pack [canvas .c]
gnuplot .c

The gnuplot command is created by evaluating the output that the gnuplot program produced. This is a little bit tricky, especially if you're wanting to do multiple plots (hint: use namespaces) but it is pretty simple to use.