top-k accuracy indicator

Determines if the true class label is among the top k predicted probabilities for each observation.

Usage

topk(prob, observed, k)

Arguments

prob

Numeric matrix of predicted probabilities (observations x classes). Column names must correspond to class labels.

observed

Factor or vector of observed class labels. Must be present in colnames(prob).

k

Integer; the number of top probabilities to consider.

Value

A data.frame with columns topk (logical indicator: TRUE if observed class is in top-k) and observed.

See also

Other classifier evaluation: rank_score()

Examples

probs <- matrix(c(0.1, 0.9, 0.8, 0.2, 0.3, 0.7), 3, 2, byrow=TRUE,
                dimnames = list(NULL, c("A", "B")))
obs <- factor(c("B", "A", "B"))
topk(probs, obs, k=1)
#>   topk observed
#> 1 TRUE        B
#> 2 TRUE        A
#> 3 TRUE        B
topk(probs, obs, k=2)
#>   topk observed
#> 1 TRUE        B
#> 2 TRUE        A
#> 3 TRUE        B