R/parameters.R

In tidymodels/discrim: Model Wrappers for Discriminant Analysis

#' Parameter objects for Regularized Discriminant Models
#'
#' `discrim_regularized()` describes the effect of `frac_common_cov()` and
#' `frac_identity()`. `smoothness()` is an alias for the `adjust` parameter in
#' `stats::density()`.
#'
#' @param range A two-element vector holding the _defaults_ for the smallest and
#' largest possible values, respectively.
#'
#' @param trans A `trans` object from the `scales` package, such as
#' `scales::log10_trans()` or `scales::reciprocal_trans()`. If not provided,
#' the default is used which matches the units used in `range`. If no
#' transformation, `NULL`.
#'
#' @return A function with classes "quant_param" and "param"
#'
#' @details
#' These parameters can modulate a RDA model to go between linear and quadratic
#' class boundaries.
#' @examples
#' frac_common_cov()
#' @export
frac_common_cov <- function(range = c(0, 1), trans = NULL) {
  dials::new_quant_param(
    type = "double",
    range = range,
    inclusive = c(TRUE, TRUE),
    trans = trans,
    label = c(frac_common_cov = "Fraction of the Common Covariance Matrix"),
    finalize = NULL
  )
}

#' @export
#' @rdname frac_common_cov
frac_identity <- function(range = c(0, 1), trans = NULL) {
  dials::new_quant_param(
    type = "double",
    range = range,
    inclusive = c(TRUE, TRUE),
    trans = trans,
    label = c(frac_identity = "Fraction of the Identity Matrix"),
    finalize = NULL
  )
}

#' @export
#' @rdname frac_common_cov
smoothness <- function(range = c(0.5, 1.5), trans = NULL) {
  dials::new_quant_param(
    type = "double",
    range = range,
    inclusive = c(TRUE, TRUE),
    trans = trans,
    label = c(smoothness = "Kernel Smoothness"),
    finalize = NULL
  )
}