make_class_pred function

Create a class_pred vector from class probabilities

These functions can be used to convert class probability estimates to class_pred objects with an optional equivocal zone.

make_class_pred(..., levels, ordered = FALSE, min_prob = 1/length(levels))

make_two_class_pred(
  estimate,
  levels,
  threshold = 0.5,
  ordered = FALSE,
  buffer = NULL
)

Arguments

• ...: Numeric vectors corresponding to class probabilities. There should be one for each level in levels, and it is assumed that the vectors are in the same order as levels.

• levels: A character vector of class levels. The length should be the same as the number of selections made through ..., or length 2

  for make_two_class_pred().

• ordered: A single logical to determine if the levels should be regarded as ordered (in the order given). This results in a class_pred object that is flagged as ordered.

• min_prob: A single numeric value. If any probabilities are less than this value (by row), the row is marked as equivocal.

• estimate: A single numeric vector corresponding to the class probabilities of the first level in levels.

• threshold: A single numeric value for the threshold to call a row to be labeled as the first value of levels.

• buffer: A numeric vector of length 1 or 2 for the buffer around threshold that defines the equivocal zone (i.e., threshold - buffer[1] to threshold + buffer[2]). A length 1 vector is recycled to length 2. The default, NULL, is interpreted as no equivocal zone.

Returns

A vector of class class_pred.

Examples

library(dplyr)

good <- segment_logistic$.pred_good
lvls <- levels(segment_logistic$Class)

# Equivocal zone of .5 +/- .15
make_two_class_pred(good, lvls, buffer = 0.15)

# Equivocal zone of c(.5 - .05, .5 + .15)
make_two_class_pred(good, lvls, buffer = c(0.05, 0.15))

# These functions are useful alongside dplyr::mutate()
segment_logistic %>%
  mutate(
    .class_pred = make_two_class_pred(
      estimate = .pred_good,
      levels = levels(Class),
      buffer = 0.15
    )
  )

# Multi-class example
# Note that we provide class probability columns in the same
# order as the levels
species_probs %>%
  mutate(
    .class_pred = make_class_pred(
      .pred_bobcat, .pred_coyote, .pred_gray_fox,
      levels = levels(Species),
      min_prob = .5
    )
  )