63 lines
2.3 KiB
R
63 lines
2.3 KiB
R
% Generated by roxygen2: do not edit by hand
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% Please edit documentation in R/callbacks.R
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\name{cb.early.stop}
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\alias{cb.early.stop}
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\title{Callback closure to activate the early stopping.}
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\usage{
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cb.early.stop(stopping_rounds, maximize = FALSE, metric_name = NULL,
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verbose = TRUE)
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}
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\arguments{
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\item{stopping_rounds}{The number of rounds with no improvement in
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the evaluation metric in order to stop the training.}
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\item{maximize}{whether to maximize the evaluation metric}
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\item{metric_name}{the name of an evaluation column to use as a criteria for early
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stopping. If not set, the last column would be used.
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Let's say the test data in \code{watchlist} was labelled as \code{dtest},
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and one wants to use the AUC in test data for early stopping regardless of where
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it is in the \code{watchlist}, then one of the following would need to be set:
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\code{metric_name='dtest-auc'} or \code{metric_name='dtest_auc'}.
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All dash '-' characters in metric names are considered equivalent to '_'.}
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\item{verbose}{whether to print the early stopping information.}
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}
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\description{
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Callback closure to activate the early stopping.
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}
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\details{
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This callback function determines the condition for early stopping
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by setting the \code{stop_condition = TRUE} flag in its calling frame.
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The following additional fields are assigned to the model's R object:
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\itemize{
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\item \code{best_score} the evaluation score at the best iteration
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\item \code{best_iteration} at which boosting iteration the best score has occurred (1-based index)
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\item \code{best_ntreelimit} to use with the \code{ntreelimit} parameter in \code{predict}.
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It differs from \code{best_iteration} in multiclass or random forest settings.
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}
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The Same values are also stored as xgb-attributes:
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\itemize{
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\item \code{best_iteration} is stored as a 0-based iteration index (for interoperability of binary models)
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\item \code{best_msg} message string is also stored.
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}
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At least one data element is required in the evaluation watchlist for early stopping to work.
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Callback function expects the following values to be set in its calling frame:
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\code{stop_condition},
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\code{bst_evaluation},
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\code{rank},
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\code{bst} (or \code{bst_folds} and \code{basket}),
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\code{iteration},
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\code{begin_iteration},
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\code{end_iteration},
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\code{num_parallel_tree}.
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}
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\seealso{
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\code{\link{callbacks}},
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\code{\link{xgb.attr}}
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}
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