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makeNoFeaturesModel = function(targets, task.desc) {
setClasses(list(targets = targets, task.desc = task.desc),
"NoFeaturesModel")
}
predictNofeatures = function(model, newdata) {
y = getLearnerModel(model)$targets
type = model$learner$type
# for regression return constant mean
if (type == "regr") {
return(rep(mean(y), nrow(newdata)))
}
if (type == "classif") {
tab = prop.table(table(y))
probs = as.numeric(tab)
if (model$learner$predict.type == "response") {
return(sample(as.factor(names(tab)), nrow(newdata), prob = probs, replace = TRUE))
}
probs = t(replicate(nrow(newdata), probs))
colnames(probs) = names(tab)
return(probs)
}
if (type == "surv") {
if (model$learner$predict.type == "response") {
return(runif(nrow(newdata)))
}
# FIXME: probs / brier for survival should use something like median survival time
}
stopf("NoFeaturesModel for learner type '%s' not implemented", type)
}
|
