def minimize_distance_from(self, other, quiet=True):
"""
Reorders the stabilizer group generators of this code to minimize
the Hamming distance with the group generators of another code,
using a greedy heuristic algorithm.
"""
self_gens = self.group_generators
other_gens = other.group_generators
for idx_generator in range(len(self_gens)):
min_hdist = self.nq + 1 # Effectively infinite.
min_wt = self.nq + 1
best_gen = None
best_gen_decomp = ()
for stab_elems in p.powerset(self_gens[idx_generator:]):
if len(stab_elems) > 0:
stab_elem = reduce(op.mul, stab_elems)
hd = stab_elem.hamming_dist(other_gens[idx_generator])
if hd <= min_hdist and stab_elem.wt <= min_wt and (
hd < min_hdist or stab_elem.wt < min_wt):
min_hdist = hd
min_wt = stab_elem.wt
best_gen = stab_elem
best_gen_decomp = stab_elems
assert best_gen is not None, "Powerset iteration failed."
if best_gen in self_gens:
# Swap so that it lies at the front.
idx = self_gens.index(best_gen)
if not quiet and idx != idx_generator:
print('Swap move: {} <-> {}'.format(idx_generator, idx))
self_gens[idx_generator], self_gens[idx] = self_gens[
idx], self_gens[idx_generator]
else:
# Set the head element to best_gen, correcting the rest
# as needed.
if self_gens[idx_generator] in best_gen_decomp:
if not quiet:
print('Set move: {} = {}'.format(
idx_generator, best_gen))
self_gens[idx_generator] = best_gen
else:
if not quiet:
print('Mul move: {} *= {}'.format(
idx_generator, best_gen))
self_gens[idx_generator] *= best_gen
return self
def minimize_distance_from(self, other, quiet=True):
"""
Reorders the stabilizer group generators of this code to minimize
the Hamming distance with the group generators of another code,
using a greedy heuristic algorithm.
"""
self_gens = self.group_generators
other_gens = other.group_generators
for idx_generator in range(len(self_gens)):
min_hdist = self.nq + 1 # Effectively infinite.
min_wt = self.nq + 1
best_gen = None
best_gen_decomp = ()
for stab_elems in p.powerset(self_gens[idx_generator:]):
if len(stab_elems) > 0:
stab_elem = reduce(op.mul, stab_elems)
hd = stab_elem.hamming_dist(other_gens[idx_generator])
if hd <= min_hdist and stab_elem.wt <= min_wt and (hd < min_hdist or stab_elem.wt < min_wt):
min_hdist = hd
min_wt = stab_elem.wt
best_gen = stab_elem
best_gen_decomp = stab_elems
assert best_gen is not None, "Powerset iteration failed."
if best_gen in self_gens:
# Swap so that it lies at the front.
idx = self_gens.index(best_gen)
if not quiet and idx != idx_generator:
print 'Swap move: {} <-> {}'.format(idx_generator, idx)
self_gens[idx_generator], self_gens[idx] = self_gens[idx], self_gens[idx_generator]
else:
# Set the head element to best_gen, correcting the rest
# as needed.
if self_gens[idx_generator] in best_gen_decomp:
if not quiet:
print 'Set move: {} = {}'.format(idx_generator, best_gen)
self_gens[idx_generator] = best_gen
else:
if not quiet:
print 'Mul move: {} *= {}'.format(idx_generator, best_gen)
self_gens[idx_generator] *= best_gen
return self
