Re: your mail

Jon Berry (berryj@numen.elon.edu)
Fri, 21 Nov 1997 14:48:23 -0500 (EST)


I suspect that you haven't called the function yet. The code you have
below *defines* the function. To call it:

1. click with the left button in a graph window
2. (at STk>) (forefather-binding (current-graph-view))

now you should be able to click on a vertex, hit the "f" key, and see
its forefather flash.

Note that STk provides you with Scheme, a standard functional programming
language. The standard is available at:

http://www.cs.rice.edu/CS/PLT/packages/doc/r4rs/index.html

and other places.

It would be a good idea to spend an hour or two looking at the language.
Then the STk manual would be good reading to gear up for manipulating
graphs.

Jon

Dr. Jon Berry Office: Whitley 204
Assistant Professor, Computing Sciences Campus Box: 2130
Elon College, N.C. 27244 Office Phone: (910)584-2290

On Fri, 21 Nov 1997, Graph Theory Project wrote:

> Hi:
> last time I asked you about the articel" Graph Drawing and ..."
> Figure 6, after I draw a picture, and typed:
>
> (define (forefather-binding graph-view)
> (strongly-connected-components (graph graph-view))
> (bind (slot-ref graph-view 'graph-toplevel) "<KeyPress-f>"
> (lambda (x y)
> (flash (vertex-item
> (find-vertex-attribute 'forefather
> (slot-ref (car *link:selected-vertex-item*) 'vertex))graph-view)))))
>
> then it appeared the #undefined
>
> then I click one vertice on the graph, and type f, there is nothing happened.
> I do not know why, I tried two types to type f, first on graph, I just type key
> f, second I type f on STK>, third I type f on stk then return, it appeared
> there is error, I do not know why?
>
> best wishes!
>
> Mei Liu
>
>