Hellooo,
> You are right in that the drawings output by sage do not correspond to the
> planar embedding. The get_embedding method says vertices are ordered in
> clockwise order whereas the drawing output by sage displays them in
> counter-clockwise order.
Oh. So you say that we should
Hello Nathann,
Thanks again..
Yesterday evening I made a pause about my sagemath worries...and read
(again) one math paper...including Schnyder woods, and once again authors
are
requiring that the graph is "maximum planar" (or "triangulated") and, as
you have discovered, my example is not
"Change the doc"
yes, I am suggesting that for the planar layout; if the input graph is not
maximal planar
and you can add a simple function checking that one graph is maximal planar
(simple to code : loop on each couple of vertices, and add edge made of
this couple, if adding make graph not
That is a very nice function. One thing to note is that having edges added
in this way may bump up the running time above O(n), since we would have to
be testing that planarity is preserved after adding a given edge.
I do agree that sometimes the drawings output by the planar layout are not
Boost provides a make_maximal_planar function ... and this function can be
parametrized by a addEdgeVisitor
http://www.boost.org/doc/libs/1_36_0/libs/graph/doc/make_maximal_planar.html
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@fidelbc : I didn't know that condition about m = 3n - 6 ... but now I
found it (from Euler formula) for example
https://en.wikipedia.org/wiki/F%C3%A1ry%27s_theorem
For drawing a planar and not maximal planar graph, a "straight" edge
drawing would satisfy me
In some papers (for example :
It is simpler to check if a graph is maximal planar. If you already know
the graph is planar, then just check if it has 3n-6 edges. If it does, then
it is maximal, otherwise it isn't.
What planar layout do you suggest for graphs that are not maximal planar?
f
On Monday, October 19, 2015 at
