note for future struct::graph development

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Also note GraphViz @ http://www.graphviz.org/
Particularly interesting are "tclgdr" and "tclgdl"
for the manipulation and layouting of graph
structures. tcllib/struct/graph api compatible
wrapper would be nice and also give as the capability
to read and write DOT, the language of GraphViz.

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I'm currently looking into coding a c version to reduce
memory consumption and speed (i like the tcllib interface,
but it is a bit slow using 150 000 + Nodes...), perhaps
there are some ideas how this could be done. Any help
appreciated.

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Whow, there do you use 150 000+ nodes ?

Seriously. We have a command per graph. The implementation
(= C function) of this command should be shared, and be
given a reference to the actual graph structure during
registration as true tcl command (ClientData of tcl
commands!). In the shared implementation cast the incoming
clientdata into the correct pointer to the graph structure
and then just use it.

nodes, arcs. Use hashtables to map from node and arc names
to the structures hold information about them. Interlink
these structure. For example an arc structure should
contain references to the two nodes the arc is connected
too. Same for node structures, should have references to
all incoming and outgoing arcs. Possibilities here are
dynamically allocated arrays, linked lists, hash tables,
Tcl_Obj => list functionality.

A C implementation would be great.

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there do you = where do you

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More notes:

* Structure the system in two layers
- Actual graph handling layer
- Glue between that and Tcl

* Investigate existing C coded graph layers, reduce effort
by having to write only the glue layer.

- http://www.graphviz.org
- The implementation provided "The Stanford Graphbase"
(http://www.amazon.de/exec/obidos/ASIN/0201542757/)
- http://www.informatik.uni-bremen.de/daVinci/
... more

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I have finished a c coded version of the tcllib 1.3 version.
It can be found at:

http://purl.oclc.org/NET/schlenk/tcl/cgraph

Michael

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Raising the priority of the item because its inclusion in the
upcoming release was proposed in the Tcllib-devel mailing list.

Supporting or contrarian statements should be made on the
referenced mailing list for public discussion.