def initialize_heaps(data, n_neighbors, leaf_array):
graph_heap = make_heap(data.shape[0], 10)
search_heap = make_heap(data.shape[0], n_neighbors * 2)
tried = set([(-1, -1)])
for n in range(leaf_array.shape[0]):
for i in range(leaf_array.shape[1]):
if leaf_array[n, i] < 0:
break
for j in range(i + 1, leaf_array.shape[1]):
if leaf_array[n, j] < 0:
break
if (leaf_array[n, i], leaf_array[n, j]) in tried:
continue
d = dist(data[leaf_array[n, i]], data[leaf_array[n, j]],
*dist_args)
unchecked_heap_push(graph_heap, leaf_array[n, i], d,
leaf_array[n, j], 1)
unchecked_heap_push(graph_heap, leaf_array[n, j], d,
leaf_array[n, i], 1)
unchecked_heap_push(search_heap, leaf_array[n, i], d,
leaf_array[n, j], 1)
unchecked_heap_push(search_heap, leaf_array[n, j], d,
leaf_array[n, i], 1)
tried.add((leaf_array[n, i], leaf_array[n, j]))
return graph_heap, search_heap
def init_from_random(n_neighbors, data, query_points, heap, rng_state):
for i in range(query_points.shape[0]):
indices = rejection_sample(n_neighbors, data.shape[0], rng_state)
for j in range(indices.shape[0]):
if indices[j] < 0:
continue
d = dist(data[indices[j]], query_points[i], *dist_args)
heap_push(heap, i, d, indices[j], 1)
return
def init_from_tree(tree, data, query_points, heap, rng_state):
for i in range(query_points.shape[0]):
indices = search_flat_tree(
query_points[i],
tree.hyperplanes,
tree.offsets,
tree.children,
tree.indices,
rng_state,
)
for j in range(indices.shape[0]):
if indices[j] < 0:
continue
d = dist(data[indices[j]], query_points[i], *dist_args)
heap_push(heap, i, d, indices[j], 1)
return
def initialized_nnd_search(data, indptr, indices, initialization,
query_points):
for i in numba.prange(query_points.shape[0]):
tried = set(initialization[0, i])
while True:
# Find smallest flagged vertex
vertex = smallest_flagged(initialization, i)
if vertex == -1:
break
candidates = indices[indptr[vertex]:indptr[vertex + 1]]
for j in range(candidates.shape[0]):
if (candidates[j] == vertex or candidates[j] == -1
or candidates[j] in tried):
continue
d = dist(data[candidates[j]], query_points[i], *dist_args)
unchecked_heap_push(initialization, i, d, candidates[j], 1)
tried.add(candidates[j])
return initialization
def nn_descent(
data,
n_neighbors,
rng_state,
max_candidates=50,
n_iters=10,
delta=0.001,
rho=0.5,
rp_tree_init=True,
leaf_array=None,
verbose=False,
):
n_vertices = data.shape[0]
current_graph = make_heap(data.shape[0], n_neighbors)
for i in range(data.shape[0]):
indices = rejection_sample(n_neighbors, data.shape[0], rng_state)
for j in range(indices.shape[0]):
d = dist(data[i], data[indices[j]], *dist_args)
heap_push(current_graph, i, d, indices[j], 1)
heap_push(current_graph, indices[j], d, i, 1)
if rp_tree_init:
for n in range(leaf_array.shape[0]):
for i in range(leaf_array.shape[1]):
if leaf_array[n, i] < 0:
break
for j in range(i + 1, leaf_array.shape[1]):
if leaf_array[n, j] < 0:
break
d = dist(data[leaf_array[n, i]],
data[leaf_array[n, j]], *dist_args)
heap_push(current_graph, leaf_array[n, i], d,
leaf_array[n, j], 1)
heap_push(current_graph, leaf_array[n, j], d,
leaf_array[n, i], 1)
for n in range(n_iters):
if verbose:
print("\t", n, " / ", n_iters)
candidate_neighbors = build_candidates(current_graph, n_vertices,
n_neighbors, max_candidates,
rng_state)
c = 0
for i in range(n_vertices):
for j in range(max_candidates):
p = int(candidate_neighbors[0, i, j])
if p < 0 or tau_rand(rng_state) < rho:
continue
for k in range(max_candidates):
q = int(candidate_neighbors[0, i, k])
if (q < 0 or not candidate_neighbors[2, i, j]
and not candidate_neighbors[2, i, k]):
continue
d = dist(data[p], data[q], *dist_args)
c += heap_push(current_graph, p, d, q, 1)
c += heap_push(current_graph, q, d, p, 1)
if c <= delta * n_neighbors * data.shape[0]:
break
return deheap_sort(current_graph)