index_search: Search for Nearest Neighbors

In usearchlite: Local Vector Search with 'USearch'

Search for Nearest Neighbors

Description

Searches the index for the k nearest neighbors of the query vector(s).

Usage

index_search(index, query, k = 10L, filter = NULL, prefilter_k = 100L)

Arguments

index	An usearchlite_index object.
query	Numeric vector of length dim, or matrix with dim columns for batch queries.
k	Integer. Number of nearest neighbors to return.
filter	Optional function that takes the metadata data.frame and returns a logical vector indicating which rows to keep, or a filtered data.frame.
prefilter_k	Integer. Number of candidates to retrieve from the C++ layer before applying the filter. Should be >= k.

Value

A list with components:

ids

Integer vector (or matrix for batch) of neighbor IDs

distances

Numeric vector (or matrix for batch) of distances

meta

Data.frame of metadata for returned IDs

Examples

tmp <- tempfile()
dir.create(tmp)
idx <- index_new(3L, tmp)
idx <- index_add(idx, 1L, c(1, 0, 0), meta = list(category = "a"))
idx <- index_add(idx, 2L, c(0, 1, 0), meta = list(category = "b"))
res <- index_search(idx, c(1, 0, 0), k = 2L)
res <- index_search(idx, c(1, 0, 0), k = 2L,
                    filter = function(m) m$category == "a")
unlink(tmp, recursive = TRUE)

usearchlite documentation built on Feb. 13, 2026, 1:06 a.m.