def _segmentation_impl(self, graph, costs, time_limit=None, **kwargs):
objective = nmc.multicutObjective(graph, costs)
if self.solver == 'greedy-additive':
solver_impl = objective.greedyAdditiveFactory().create(objective)
elif self.solver == 'kernighan-lin':
warmstart = self.solver_options.get('warmstart_greedy', True)
# TODO need to set this if we use verbosity
# greedyVisitNth = kwargs.pop('greedyVisitNth', 100)
solver_impl = objective.kernighanLinFactory(
warmStartGreedy=warmstart).create(objective)
elif self.solver == 'fusion-moves':
solver_impl = self._get_fusion_moves(objective)
elif self.solver == 'ilp':
ilp_backend = self.solver_options.get("ilp_backend", None)
solver_impl = objective.multicutIlpFactory(
ilpSolver=ilp_backend).create(objective)
# TODO this needs to change once we suport verbosity / logging
if time_limit is None:
node_labels = solver_impl.optimize()
else:
visitor = objective.verboseVisitor(visitNth=100000000,
timeLimitSolver=time_limit)
node_labels = solver_impl.optimize(visitor=visitor)
return node_labels
def multicut_kernighan_lin(graph,
costs,
time_limit=None,
warmstart=True,
**kwargs):
""" Solve multicut problem with kernighan lin solver.
Introduced in "An efficient heuristic procedure for partitioning graphs":
http://xilinx.asia/_hdl/4/eda.ee.ucla.edu/EE201A-04Spring/kl.pdf
Arguments:
graph [nifty.graph] - graph of multicut problem
costs [np.ndarray] - edge costs of multicut problem
time_limit [float] - time limit for inference (default: None)
warmstart [bool] - whether to warmstart with gaec solution (default: True)
"""
objective = nmc.multicutObjective(graph, costs)
solver = objective.kernighanLinFactory(
warmStartGreedy=warmstart).create(objective)
if time_limit is None:
return solver.optimize()
else:
visitor = objective.verboseVisitor(visitNth=1000000,
timeLimitTotal=time_limit)
return solver.optimize(visitor=visitor)
def _compute_mc(self, input_, feat_function, beta):
# watershed and region adjacency graph
ws, n_labels = self._compute_ws(input_)
rag = nrag.gridRag(ws,
numberOfLabels=n_labels,
numberOfThreads=self.n_threads)
if rag.numberOfEdges == 0:
return np.zeros_like(ws)
# features and features to costs
feats = feat_function(rag, input_)
probs, edge_len = feats[:, 0], feats[:, -1]
costs = self._probs_to_costs(probs, edge_len, beta)
# graph and multicut solver
graph = nifty.graph.undirectedGraph(rag.numberOfNodes)
graph.insertEdges(rag.uvIds())
objective = nmc.multicutObjective(graph, costs)
solver = objective.kernighanLinFactory(
warmStartGreedy=True).create(objective)
# solve multicut and project back to segmentation
# TODO time limit
node_labels = solver.optimize()
return nrag.projectScalarNodeDataToPixels(
rag, node_labels, numberOfThreads=self.n_threads)
def _to_objective(graph, costs):
if isinstance(graph, nifty.graph.UndirectedGraph):
graph_ = graph
else:
graph_ = nifty.graph.undirectedGraph(graph.numberOfNodes)
graph_.insertEdges(graph.uvIds())
objective = nmc.multicutObjective(graph_, costs)
return objective
def multicut_gaec(graph, costs, time_limit=None, n_threads=1):
objective = nmc.multicutObjective(graph, costs)
solver = objective.greedyAdditiveFactory().create(objective)
if time_limit is None:
return solver.optimize()
else:
visitor = objective.verboseVisitor(visitNth=1000000,
timeLimitTotal=time_limit)
return solver.optimize(visitor=visitor)
def multicut_kernighan_lin(graph, costs, warmstart=True, time_limit=None, n_threads=1):
objective = nmc.multicutObjective(graph, costs)
solver = objective.kernighanLinFactory(warmStartGreedy=warmstart).create(objective)
if time_limit is None:
return solver.optimize()
else:
visitor = objective.verboseVisitor(visitNth=1000000,
timeLimitTotal=time_limit)
return solver.optimize(visitor=visitor)
def multicut_fusion_moves(graph, costs, time_limit=None, n_threads=1,
solver='kernighan-lin'):
assert solver in ('kernighan-lin', 'greedy-additive')
objective = nmc.multicutObjective(graph, costs)
if time_limit is None:
return solver.optimize()
else:
visitor = objective.verboseVisitor(visitNth=1000000,
timeLimitTotal=time_limit)
return solver.optimize(visitor=visitor)
def _test_multicut(self, solver):
# TODO remove the try-except once download is implemented
try:
graph, costs = self.load_problem(self.problem_root)
except FileNotFoundError:
return
node_labels = solver(graph, costs)
obj = nmc.multicutObjective(graph, costs)
energy = obj.evalNodeLabels(node_labels)
self.assertGreater(self.upper_bound, energy)
def multicut_fusion_moves(graph,
costs,
time_limit=None,
n_threads=1,
internal_solver='kernighan-lin',
seed_fraction=.05,
num_it=1000,
num_it_stop=10):
""" Solve multicut problem with fusion moves solver.
Introduced in "Fusion moves for correlation clustering":
http://openaccess.thecvf.com/content_cvpr_2015/papers/Beier_Fusion_Moves_for_2015_CVPR_paper.pdf
Arguments:
graph [nifty.graph] - graph of multicut problem
costs [np.ndarray] - edge costs of multicut problem
time_limit [float] - time limit for inference (default: None)
n_threasd [int] - number of threads (default: 1)
internal_solver [str] - name of solver used for connected components
(default: 'kernighan-lin')
seed_fraction [float] - fraction of nodes used as seeds for proposal generation
(default: .05)
num_it [int] - maximal number of iterations (default: 1000)
num_it_stop [int] - stop if no improvement after num_it_stop (default: 1000)
"""
assert internal_solver in ('kernighan-lin', 'greedy-additive')
objective = nmc.multicutObjective(graph, costs)
if internal_solver == 'kernighan-lin':
sub_solver = objective.greedyAdditiveFactory()
else:
sub_solver = objective.kernighanLinFactory(warmStartGreedy=True)
sub_solver = objective.fusionMoveSettings(mcFactory=sub_solver)
proposal_gen = objective.watershedProposals(sigma=10,
seedFraction=seed_fraction)
solver = objective.fusionMoveBasedFactory(
fusionMove=sub_solver,
verbose=1,
fuseN=2,
proposalGen=proposal_gen,
numberOfIterations=num_it,
numberOfParallelProposals=2 * n_threads,
numberOfThreads=n_threads,
stopIfNoImprovement=num_it_stop).create(objective)
if time_limit is None:
return solver.optimize()
else:
visitor = objective.verboseVisitor(visitNth=1000000,
timeLimitTotal=time_limit)
return solver.optimize(visitor=visitor)
def solve_multicut(graph, costs):
assert graph.numberOfEdges == len(costs)
_logger.debug('Creating multi-cut object from graph %s and costs %s',
graph, costs.shape)
_logger.trace('Costs are %s', costs)
# TODO why do lower costs mean cut the edge?
# Qutoing @constantinpape
# the cost can be in ]-inf, inf[ (I usually clip at ~ ]-6, 6[),
# where negative costs are repulsive (i.e. nodes are more likely to be disconnected)
# and positive costs are attractive
objective = nifty_mc.multicutObjective(graph, costs)
solver = objective.kernighanLinFactory(
warmStartGreedy=True).create(objective)
return solver.optimize()
def multicut_gaec(graph, costs, time_limit=None, **kwargs):
""" Solve multicut problem with greedy-addtive edge contraction solver.
Introduced in "Fusion moves for correlation clustering":
http://openaccess.thecvf.com/content_cvpr_2015/papers/Beier_Fusion_Moves_for_2015_CVPR_paper.pdf
Arguments:
graph [nifty.graph] - graph of multicut problem
costs [np.ndarray] - edge costs of multicut problem
time_limit [float] - time limit for inference (default: None)
"""
objective = nmc.multicutObjective(graph, costs)
solver = objective.greedyAdditiveFactory().create(objective)
if time_limit is None:
return solver.optimize()
else:
visitor = objective.verboseVisitor(visitNth=1000000,
timeLimitTotal=time_limit)
return solver.optimize(visitor=visitor)
def _test_multicut(self, solver, **kwargs):
graph, costs = load_multicut_problem('A', 'small', self.problem_path)
node_labels = solver(graph, costs, **kwargs)
obj = nmc.multicutObjective(graph, costs)
energy = obj.evalNodeLabels(node_labels)
self.assertGreater(self.upper_bound, energy)
def _check_result(self, graph, costs, node_labels):
self.assertEqual(graph.numberOfNodes, len(node_labels))
obj = nmc.multicutObjective(graph, costs)
energy = obj.evalNodeLabels(node_labels)
self.assertGreater(self.upper_bound, energy)
return energy
