[R] docs update - callbacks and parameter style

R-package/man/cb.cv.predict.Rd

@@ -0,0 +1,43 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/callbacks.R
+\name{cb.cv.predict}
+\alias{cb.cv.predict}
+\title{Callback closure for returning cross-validation based predictions.}
+\usage{
+cb.cv.predict(save_models = FALSE)
+}
+\arguments{
+\item{save_models}{a flag for whether to save the folds' models.}
+}
+\value{
+Predictions are returned inside of the \code{pred} element, which is either a vector or a matrix,
+depending on the number of prediction outputs per data row. The order of predictions corresponds 
+to the order of rows in the original dataset. Note that when a custom \code{folds} list is 
+provided in \code{xgb.cv}, the predictions would only be returned properly when this list is a 
+non-overlapping list of k sets of indices, as in a standard k-fold CV. The predictions would not be 
+meaningful when user-profided folds have overlapping indices as in, e.g., random sampling splits.
+When some of the indices in the training dataset are not included into user-provided \code{folds},
+their prediction value would be \code{NA}.
+}
+\description{
+Callback closure for returning cross-validation based predictions.
+}
+\details{
+This callback function saves predictions for all of the test folds,
+and also allows to save the folds' models.
+
+It is a "finalizer" callback and it uses early stopping information whenever it is available,
+thus it must be run after the early stopping callback if the early stopping is used.
+
+Callback function expects the following values to be set in its calling frame:
+\code{bst_folds},
+\code{basket},
+\code{data},
+\code{end_iteration},
+\code{num_parallel_tree},
+\code{num_class}.
+}
+\seealso{
+\code{\link{callbacks}}
+}
+