Any elegant way to construct the complete $k$-partite graph in Python?
Paul Miller
paul.w.miller.please.dont.spam.me at wmich.edu
Mon Nov 23 19:05:33 EST 2009
I was wondering if there were any neat tools (like for instance,
something from itertools) that would help me write the following function
more elegantly. The return value should, of course, be the complete $k$-
partite graph $K_{n_1, n_2, \dots, n_k}$:
def completeGraph (*ns):
'''
Returns the complete graph $K_{n_1, n_2, \dots, n_k}$ when passed
the sequence \code {n_1, n_2, \dots, n_k}.
'''
if len (ns) == 1:
return completeGraph ( * ([1] * ns[0]) )
n = sum (ns)
vertices = range (n)
partition_indices = [sum (ns[:i]) for i in range (len (ns))]
partite_sets = [vertices[partition_indices[i]:partition_indices[i+1]]
\
for i in range (len (partition_indices) - 1)]
partite_sets.append (vertices[partition_indices [-1]:] )
edges = []
for i in range (len (partite_sets)):
for j in range (i + 1, len (partite_sets)):
edges.extend ([ (u, v) for u in partite_sets [i] for v in \
partite_sets [j] ])
return graph.Graph (vertices = vertices, edges = edges)
Many thanks!
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