#' Conditional Random Forest Model
#'
#' An implementation of the random forest and bagging ensemble algorithms
#' utilizing conditional inference trees as base learners.
#'
#' @param teststat character specifying the type of the test statistic to be
#' applied.
#' @param testtype character specifying how to compute the distribution of the
#' test statistic.
#' @param mincriterion value of the test statistic that must be exceeded in
#' order to implement a split.
#' @param replace logical indicating whether sampling of observations is done
#' with or without replacement.
#' @param fraction fraction of number of observations to draw without
#' replacement (only relevant if \code{replace = FALSE}).
#' @param ntree number of trees to grow in a forest.
#' @param mtry number of input variables randomly sampled as candidates at each
#' node for random forest like algorithms.
#'
#' @details
#' \describe{
#' \item{Response types:}{\code{factor}, \code{numeric}, \code{Surv}}
#' \item{\link[=TunedModel]{Automatic tuning} of grid parameter:}{
#' \code{mtry}
#' }
#' }
#'
#' Supplied arguments are passed to \code{\link[party]{cforest_control}}.
#' Further model details can be found in the source link below.
#'
#' @return \code{MLModel} class object.
#'
#' @seealso \code{\link[party]{cforest}}, \code{\link{fit}},
#' \code{\link{resample}}
#'
#' @examples
#' fit(sale_amount ~ ., data = ICHomes, model = CForestModel)
#'
CForestModel <- function(
teststat = c("quad", "max"),
testtype = c("Univariate", "Teststatistic", "Bonferroni", "MonteCarlo"),
mincriterion = 0, ntree = 500, mtry = 5, replace = TRUE, fraction = 0.632
) {
teststat <- match.arg(teststat)
testtype <- match.arg(testtype)
MLModel(
name = "CForestModel",
label = "Conditional Random Forests",
packages = "party",
response_types = c("factor", "numeric", "Surv"),
weights = TRUE,
predictor_encoding = "model.frame",
na.rm = "response",
params = new_params(environment()),
gridinfo = new_gridinfo(
param = "mtry",
get_values = c(
function(n, data, ...) seq_nvars(data, CForestModel, n)
)
),
fit = function(formula, data, weights, ...) {
party::cforest(
formula, data = as.data.frame(formula, data = data), weights = weights,
controls = party::cforest_control(...)
)
},
predict = function(object, newdata, .MachineShop, ...) {
newdata <- as.data.frame(newdata)
if (object@responses@is_censored) {
y <- response(.MachineShop$input)
fits <- predict(object, newdata = newdata, type = "prob")
predict(y, fits, ...)
} else {
predict(object, newdata = newdata, type = "prob") %>%
unlist %>%
matrix(nrow = nrow(newdata), byrow = TRUE)
}
},
varimp = function(object, .MachineShop, ...) {
structure(
party::varimp(object, ...),
metric = if (object@responses@is_censored) "brier" else "accuracy"
)
}
)
}
MLModelFunction(CForestModel) <- NULL
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