It's my understanding that neato is an implementation of Kamada-Kwai, which
is going to try to match the distance between two nodes in the
two-dimensional drawing to a pre-defined distance between nodes. By default,
I think this distance is defined as the length of the shortest path between
two nodes, but I'm pretty sure it can be overridden.

I would say that "dot", as a Sugiyama layout, is just going to try to keep
edge lengths short. Sometimes, due to the constraints of the layout, edges
can be quite long. I'm a little surprised that 'len' works with dot, since
the documentation appears to say otherwise.

Michael

On Sun, May 30, 2010 at 3:00 PM, <prsmra01@uniroma2.it> wrote:

> Hi Guido,
> I share with you my experience and a chunk of code to better clarify the
> concepts;
> after many attempts in trying to draw graphs with defined edge lengths, my
> conclusion was that "dot" is the tool most suitable to do this,because more
> "flexible";
>  the others (neato and fdp) are more aimed to draw nice graphs instead of
> graphs with precise edge lengths(the value you put for the argument len
> doesn't affect the final result!); the only way I found to do something
> "close" to what I wanted was this: (note the argument "weight" aimed to
> force the program to take more into account the value of len parameter)
>
>  graph G  {
>
> overlap = false;
> node [shape=box,style=filled,width=.3, height=.3];
>
> ds1N -- ds1P [len=0.16,weight=15];
> ds1P -- ds2P [len=0.12,weight=5];
> ds1P -- ds2N [len=0.20,weight=5];
> ds1N -- ds2P [len=1.00,weight=18];
> ds1N -- ds2N [len=0.89,weight=15];
> ds2N -- ds2P [len= 0.48,weight=18];
>
> }
>  Hope this can help.
>
> Best,
> maria
> --
> Maria Persico, PhD
> Applied Bioinformatics Group, Biotec, TU Dresden,
> Tatzberg 47-51, 01307 Dresden
> maria.persico@biotec.tu-dresden.de
> persico.maria@gmail.com
> Phone:   +49 (0)351 463 40020
> Fax:     +49 (0)351 463 40087
>
> e-mail maria.persico@uniroma2.it
>
>
> Def. Quota "Hooiveld, Guido" <Guido.Hooiveld@wur.nl>:
>
>
>  Dear list,
>>
>> I am new to RGraphViz and currently evaluating it's options. So bare with
>> me regarding this basic question....
>>
>> Say i have three nodes, A, B and C. How can i plot a graph in which the
>> length of the edges between the nodes are user-defined? Say between A en B
>> the length should be 1, between A and C this should be 2, and between B and
>> C this should be 0.5?
>> I found that the argument "len" is able to set the length of the edges,
>> http://www.graphviz.org/pub/scm/graphviz2/doc/info/attrs.html#d:len
>> (len: Preferred edge length, in inches.)
>> Also from the info @ the link:
>> len; Edge;, double; 1.0 (neato); 0.3(fdp); fdp, neato only
>>
>>  From the above I conclude that depending on the lay-out (neato or fdp)
>>> the length of ALL edges in the graph are set to 1 and 0.3 inch,
>>> respectively.
>>>
>>
>> But how to vary the length per edge? Or is what i would like to to not
>> possible?
>>
>> Any feedback is much appreciated!
>>
>> Guido
>>
>> ------------------------------------------------
>> Guido Hooiveld, PhD
>> Nutrition, Metabolism & Genomics Group
>> Division of Human Nutrition
>> Wageningen University
>> Biotechnion, Bomenweg 2
>> NL-6703 HD Wageningen
>> the Netherlands
>> tel: (+)31 317 485788
>> fax: (+)31 317 483342
>> internet:   http://nutrigene.4t.com<http://nutrigene.4t.com/>
>> email:      guido.hooiveld@wur.nl
>>
>>
>>
>>        [[alternative HTML version deleted]]
>>
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>>
>>
>
>
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