58 lines
1.8 KiB
R
58 lines
1.8 KiB
R
% Generated by roxygen2: do not edit by hand
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% Please edit documentation in R/xgb.Booster.R
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\name{xgb.slice.Booster}
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\alias{xgb.slice.Booster}
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\alias{[.xgb.Booster}
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\title{Slice Booster by Rounds}
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\usage{
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xgb.slice.Booster(
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model,
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start,
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end = xgb.get.num.boosted.rounds(model),
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step = 1L
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)
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\method{[}{xgb.Booster}(x, i)
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}
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\arguments{
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\item{model, x}{A fitted \code{xgb.Booster} object, which is to be sliced by taking only a subset
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of its rounds / iterations.}
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\item{start}{Start of the slice (base-1 and inclusive, like R's \link{seq}).}
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\item{end}{End of the slice (base-1 and inclusive, like R's \link{seq}).
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Passing a value of zero here is equivalent to passing the full number of rounds in the
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booster object.}
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\item{step}{Step size of the slice. Passing '1' will take every round in the sequence defined by
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\verb{(start, end)}, while passing '2' will take every second value, and so on.}
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\item{i}{The indices - must be an increasing sequence as generated by e.g. \code{seq(...)}.}
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}
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\value{
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A sliced booster object containing only the requested rounds.
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}
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\description{
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Creates a new booster including only a selected range of rounds / iterations
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from an existing booster, as given by the sequence \code{seq(start, end, step)}.
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}
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\details{
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Note that any R attributes that the booster might have, will not be copied into
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the resulting object.
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}
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\examples{
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data(mtcars)
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y <- mtcars$mpg
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x <- as.matrix(mtcars[, -1])
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dm <- xgb.DMatrix(x, label = y, nthread = 1)
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model <- xgb.train(data = dm, params = list(nthread = 1), nrounds = 5)
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model_slice <- xgb.slice.Booster(model, 1, 3)
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# Prediction for first three rounds
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predict(model, x, predleaf = TRUE)[, 1:3]
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# The new model has only those rounds, so
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# a full prediction from it is equivalent
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predict(model_slice, x, predleaf = TRUE)
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}
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