I need to read some planar graphs from this website, but when I try to use read_planar in SageMath, it doesn't work when using 5reg_20-32.pc (Plane 5-regular simple connected graphs with order 20). It seems something is missing.
file = open("5reg_20-32.pc")
s=graphs._read_planar_code(file)
l=[]
for line in s:
l.append(line)
It gives:
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
/tmp/ipykernel_6268/2127516145.py in ?()
1 file = open("5reg_20-32.pc")
2 s=graphs._read_planar_code(file)
3 l=[]
----> 4 for line in s:
5 l.append(line)
/usr/lib/python3.13/site-packages/sage/graphs/graph_generators.py in ?(self, code_input, immutable)
1582 G = graph.Graph(edges_g, loops=has_loops, immutable=immutable)
1583
1584 if not (G.has_multiple_edges() or has_loops):
1585 embed_g = {i + 1: di for i, di in enumerate(g)}
-> 1586 G.set_embedding(embed_g)
1587 yield G
/usr/lib/python3.13/site-packages/sage/graphs/generic_graph.py in ?(self, embedding)
3228 ...
3229 ValueError: This method is not known to work on graphs with multiedges. Perhaps this method can be updated to handle them, but in the meantime if you want to use it please disallow multiedges using allow_multiple_edges().
3230 """
3231 self._scream_if_not_simple()
-> 3232 self._check_embedding_validity(embedding, boolean=False)
3233 self._embedding = embedding
/usr/lib/python3.13/site-packages/sage/graphs/generic_graph.py in ?(self, embedding, boolean)
3394 for u in embedding[v]:
3395 if not connected(v, u):
3396 if boolean:
3397 return False
-> 3398 raise ValueError("{} and {} are not neighbors but {} is in "
3399 "the list associated with {}".format(u, v, u, v))
3400 return True
ValueError: 10 and 6 are not neighbors but 10 is in the list associated with 6
