Base class for all nearest neighbour indices

Holds a pointer to an index living in Rust memory, plus the bits R needs to talk to it (metric, precision, shape). Never instantiated directly: use one of the algorithm classes such as HnswIndex, AnnoyIndex or ExhaustiveIndex.

The index itself is not serialised by base::saveRDS(). A restored object holds a dead pointer and every method errors. Use $save() and load_ann_index() instead.

Active bindings

n: Integer. Number of indexed samples. Read-only.
dim: Integer. Number of features. Read-only.
metric: String. Distance metric. Read-only.
precision: String. "float" or "double". Read-only.

Methods

`AnnIndex$predict()`

Find the k nearest indexed samples for each row of newdata.

Usage

AnnIndex$predict(newdata, k = 15L, return_dist = TRUE, .verbose = FALSE)

Arguments

newdata: Numeric matrix or data.frame. Queries x features, same number of features as the index.
k: Integer. Number of neighbours.
return_dist: Boolean. Return the distances as well.
.verbose: Boolean. Print progress from Rust.

Returns

A list with:

idx - Integer matrix, queries x k. 1-based row indices into the indexed data. NA where fewer than k neighbours were found.
dist - Numeric matrix, queries x k, or NULL if return_dist = FALSE. Inf where idx is NA.

`AnnIndex$query_self()`

kNN graph over the indexed data itself. Uses each index's own self-query path, which is faster than $predict() on the training data.

Usage

AnnIndex$query_self(k = 15L, return_dist = TRUE, .verbose = FALSE)

Arguments

k: Integer. Number of neighbours, including the sample itself.
return_dist: Boolean. Return the distances as well.
.verbose: Boolean. Print progress from Rust.

Returns

A list with idx and dist, as for $predict(), with one row per indexed sample.

`AnnIndex$save()`

Write the index to a directory. Read it back with load_ann_index().

Usage

AnnIndex$save(dir)

Arguments

dir: String. Target directory, created if missing.

Returns

The object, invisibly.

`AnnIndex$print()`

Print a one-line summary.

Usage

AnnIndex$print(...)

Arguments

...: Ignored.

Returns

The object, invisibly.

`AnnIndex$clone()`

The objects of this class are cloneable with this method.

Usage

AnnIndex$clone(deep = FALSE)

Arguments

deep: Whether to make a deep clone.