def _sample_kmc2_chain():
"""Returns previous centers as well as a new center sampled using k-MC2."""
# Extract the subset from the underlying batch.
start = i * self._kmc2_chain_length
end = start + self._kmc2_chain_length
subset = first_shard[start:end]
# Compute the distances from points in the subset to previous centers.
_, distances = gen_clustering_ops.nearest_neighbors(
subset, self._cluster_centers, 1)
# Sample index of new center using k-MC2 Markov chain.
new_center_index = gen_clustering_ops.kmc2_chain_initialization(
array_ops.squeeze(distances), self._seed)
# Extract actual new center.
newly_sampled_center = array_ops.reshape(
subset[new_center_index], [1, -1])
# Return concatenation with previously sampled centers.
if self._distance_metric == COSINE_DISTANCE:
newly_sampled_center = nn_impl.l2_normalize(
newly_sampled_center, dim=1)
return array_ops.concat(
[self._cluster_centers, newly_sampled_center], 0)
def _sample_kmc2_chain():
"""Returns previous centers as well as a new center sampled using k-MC2.
"""
# Extract the subset from the underlying batch.
start = i * self._kmc2_chain_length
end = start + self._kmc2_chain_length
subset = first_shard[start:end]
# Compute the distances from points in the subset to previous centers.
_, distances = gen_clustering_ops.nearest_neighbors(
subset, self._cluster_centers, 1)
# Sample index of new center using k-MC2 Markov chain.
new_center_index = gen_clustering_ops.kmc2_chain_initialization(
array_ops.squeeze(distances), self._seed)
# Extract actual new center.
newly_sampled_center = array_ops.reshape(subset[new_center_index],
[1, -1])
# Return concatenation with previously sampled centers.
if self._distance_metric == COSINE_DISTANCE:
newly_sampled_center = nn_impl.l2_normalize(
newly_sampled_center, dim=1)
return array_ops.concat([self._cluster_centers, newly_sampled_center],
0)