def bytes_n_cobs(mfld):
"""
Return a bytestring encoding of the manifold and a list of basis
changes that convert the combinatorial basis of the decoded
bytestring back to the original peripheral basis of the manifold,
and a permutation to be applied to the cusp indices.
"""
cobs = mfld.set_peripheral_curves('combinatorial', return_matrices=True)
bytestring = mfld._to_bytes()
encoded_perm = 0
N = Manifold('empty')
N._from_bytes(bytestring)
N.set_peripheral_curves('combinatorial')
mfld.set_peripheral_curves(cobs) # put it back the way it was
isoms = mfld.isomorphisms_to(N)
abcd = False
while isoms:
pick_one = isoms.pop()
abcd = tuples(pick_one)
if abcd:
break
if not abcd:
print('No orientation preserving isometries????')
return bytestring, cobs, 0
perm = pick_one.cusp_images()
for n in range(mfld.num_cusps()):
a, b, c, d = abcd[n]
cobs[perm[n]] = [[a, c], [b, d]]
encoded_perm |= (n << (perm[n] << 2))
return bytestring, cobs, encoded_perm
def _test_against_known_canonical_retriangulations():
from snappy import Manifold
for name, bytes_ in _known_canonical_retriangulations:
M = Manifold(name); K = verified_canonical_retriangulation(M)
L = Manifold('empty'); L._from_bytes(bytes_)
if not len(K.isomorphisms_to(L)):
raise Exception('%s failed' % name)