You need to define a function on pair of vertices that returns "True"
if there should be an edge.
Something like
X = Set([1,2,3,4,5])
V=(X.subsets(2))
def s(a,b):
return a.intersection(b).cardinality()==0
T = Graph([V, s])
should work, but I am getting the following weird error in sage 4.1:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call
last)
/home/network/jlopez/.sage/temp/mrcpc10.maths.qmul.ac.uk/4734/
_home_network_jlopez__sage_init_sage_0.py in <module>()
/scratch/sage/local/lib/python2.6/site-packages/sage/graphs/graph.pyc
in __init__(self, data, pos, loops, format, boundary, weighted,
implementation, sparse, vertex_labels, **kwds)
8863 if multiedges is None: multiedges = False
8864 if weighted is None: weighted = False
-> 8865 num_verts = len(data[0])
8866 verts = data[0]
8867 elif format == 'dict_of_dicts':
/scratch/sage/local/lib/python2.6/site-packages/sage/combinat/
combinat.pyc in __len__(self)
841 AttributeError: __len__ has been removed;
use .cardinality() instead
842 """
--> 843 raise AttributeError, "__len__ has been removed;
use .cardinality() instead"
844
845 def count(self):
AttributeError: __len__ has been removed; use .cardinality() instead
Is that a bug or did I do something wrong?
Cheers
Javier
On Jul 16, 4:52 pm, Taxman <taxman4...@gmail.com> wrote:
> Hi, I'm trying to construct an odd graph (http://en.wikipedia.org/wiki/
> Odd_graph).
> My first thought was to use
> X = Set([1,2,3,4,5])
> V=(X.subsets(2))
> to get the desired subsets for the vertex set. That does get the
> subsets, but converting it into a graph doesn't seem to work.
> T=Graph(V) gives:
> networkx.exception.NetworkXError: Input is not a known data type for
> conversion.
>
> The next step in constructing the graph is to create edges wherever
> the subsets of the corresponding vertices are disjoint. I didn't know
> how to go about that.
>
> Any ideas?
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