% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/xgb.Booster.R
\name{xgb.slice.Booster}
\alias{xgb.slice.Booster}
\alias{[.xgb.Booster}
\title{Slice Booster by Rounds}
\usage{
xgb.slice.Booster(
  model,
  start,
  end = xgb.get.num.boosted.rounds(model),
  step = 1L
)

\method{[}{xgb.Booster}(x, i)
}
\arguments{
\item{model, x}{A fitted \code{xgb.Booster} object, which is to be sliced by taking only a subset
of its rounds / iterations.}

\item{start}{Start of the slice (base-1 and inclusive, like R's \link{seq}).}

\item{end}{End of the slice (base-1 and inclusive, like R's \link{seq}).

Passing a value of zero here is equivalent to passing the full number of rounds in the
booster object.}

\item{step}{Step size of the slice. Passing '1' will take every round in the sequence defined by
\verb{(start, end)}, while passing '2' will take every second value, and so on.}

\item{i}{The indices - must be an increasing sequence as generated by e.g. \code{seq(...)}.}
}
\value{
A sliced booster object containing only the requested rounds.
}
\description{
Creates a new booster including only a selected range of rounds / iterations
from an existing booster, as given by the sequence \code{seq(start, end, step)}.
}
\details{
Note that any R attributes that the booster might have, will not be copied into
the resulting object.
}
\examples{
data(mtcars)
y <- mtcars$mpg
x <- as.matrix(mtcars[, -1])
dm <- xgb.DMatrix(x, label = y, nthread = 1)
model <- xgb.train(data = dm, params = list(nthread = 1), nrounds = 5)
model_slice <- xgb.slice.Booster(model, 1, 3)
# Prediction for first three rounds
predict(model, x, predleaf = TRUE)[, 1:3]

# The new model has only those rounds, so
# a full prediction from it is equivalent
predict(model_slice, x, predleaf = TRUE)
}