Neighbors Epsilon Neighborhood

Source header: cuvs/neighbors/epsilon_neighborhood.hpp

Epsilon Neighborhood L2 Operations

neighbors::epsilon_neighborhood::compute

Computes epsilon neighborhood for the given distance metric and ball size.

1 template <typename value_t, typename idx_t, typename matrix_idx_t>
2 void compute(raft::resources const& handle,
3 raft::device_matrix_view<const value_t, matrix_idx_t, raft::row_major> x,
4 raft::device_matrix_view<const value_t, matrix_idx_t, raft::row_major> y,
5 raft::device_matrix_view<bool, matrix_idx_t, raft::row_major> adj,
6 raft::device_vector_view<idx_t, matrix_idx_t> vd,
7 value_t eps,
8 cuvs::distance::DistanceType metric = cuvs::distance::DistanceType::L2Unexpanded);

The epsilon neighbors is represented by a dense boolean adjacency matrix of size m * n and an array of degrees for each vertex, which can be used as a compressed sparse row (CSR) indptr array.

Currently, only L2Unexpanded (L2-squared) distance metric is supported. Other metrics will throw an exception.

Template Parameters

Name	Type	Description
`value_t`	“	IO and math type
`idx_t`	“	Index type
`matrix_idx_t`	“	matrix indexing type

Parameters

Name	Direction	Type	Description
`handle`	in	`raft::resources const&`	raft handle to manage library resources
`x`	in	`raft::device_matrix_view<const value_t, matrix_idx_t, raft::row_major>`	first matrix [row-major] [on device] [dim = m x k]
`y`	in	`raft::device_matrix_view<const value_t, matrix_idx_t, raft::row_major>`	second matrix [row-major] [on device] [dim = n x k]
`adj`	out	`raft::device_matrix_view<bool, matrix_idx_t, raft::row_major>`	adjacency matrix [row-major] [on device] [dim = m x n]
`vd`	out	`raft::device_vector_view<idx_t, matrix_idx_t>`	vertex degree array [on device] [len = m + 1] `vd + m` stores the total number of edges in the adjacency matrix. Pass a nullptr if you don’t need this info.
`eps`	in	`value_t`	defines epsilon neighborhood radius (should be passed as squared when using L2Unexpanded metric)
`metric`	in	`cuvs::distance::DistanceType`	distance metric to use. Currently only L2Unexpanded is supported. Default: `cuvs::distance::DistanceType::L2Unexpanded`.

Returns

void