Recall of an approximate kNN result

Fraction of the true k nearest neighbours that the approximate search found, averaged over queries. Order within a row does not matter.

Usage

knn_recall(truth, approx, k = NULL)

Arguments

truth

Integer matrix. Queries x k true neighbour indices, e.g. the idx element from an ExhaustiveIndex.

approx

Integer matrix. Queries x k approximate neighbour indices.

k

Optional integer. Only the first k columns of both are compared. Defaults to ncol(approx).

Value

Numeric between 0 and 1.