Hi folks,
I'm trying to do some clean-ups [1] of the C graph module
sage/graphs/base/c_graph.pyx
I'm almost done and am about to finish off a patch. However, I need
some clarification for the method degree() of the class CGraphBackend.
As of Sage 4.4.alpha1, the definition of this method is as follows:
def degree(self, v, directed):
"""
Return the degree of the vertex ``v``.
INPUT:
- ``v`` - a vertex of the graph
EXAMPLE::
sage: from sage.graphs.base.sparse_graph import SparseGraphBackend
sage: B = SparseGraphBackend(7)
sage: B.degree(3, False)
0
"""
cdef v_int = get_vertex(v, self.vertex_ints, self.vertex_labels, self._cg)
if directed:
return self._cg._in_degree(v_int) + self._cg._out_degree(v_int)
else:
return self._cg._out_degree(v_int)
What I don't understand is the purpose of the keyword "directed". Is
it meant to signify whether or not we want to consider the orientation
of the graph when counting the degree of a vertex?
[1] http://trac.sagemath.org/sage_trac/ticket/8733
--
Regards
Minh Van Nguyen
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