54 lines
2.0 KiB
R
54 lines
2.0 KiB
R
% Generated by roxygen2: do not edit by hand
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% Please edit documentation in R/xgb.DMatrix.R
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\name{xgb.get.DMatrix.qcut}
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\alias{xgb.get.DMatrix.qcut}
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\title{Get Quantile Cuts from DMatrix}
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\usage{
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xgb.get.DMatrix.qcut(dmat, output = c("list", "arrays"))
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}
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\arguments{
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\item{dmat}{An \code{xgb.DMatrix} object, as returned by \code{\link[=xgb.DMatrix]{xgb.DMatrix()}}.}
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\item{output}{Output format for the quantile cuts. Possible options are:
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\itemize{
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\item "list"\verb{will return the output as a list with one entry per column, where each column will have a numeric vector with the cuts. The list will be named if}dmat` has column names assigned to it.
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\item \code{"arrays"} will return a list with entries \code{indptr} (base-0 indexing) and
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\code{data}. Here, the cuts for column 'i' are obtained by slicing 'data' from entries
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\code{ indptr[i]+1} to \code{indptr[i+1]}.
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}}
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}
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\value{
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The quantile cuts, in the format specified by parameter \code{output}.
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}
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\description{
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Get the quantile cuts (a.k.a. borders) from an \code{xgb.DMatrix}
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that has been quantized for the histogram method (\code{tree_method = "hist"}).
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These cuts are used in order to assign observations to bins - i.e. these are ordered
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boundaries which are used to determine assignment condition \verb{border_low < x < border_high}.
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As such, the first and last bin will be outside of the range of the data, so as to include
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all of the observations there.
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If a given column has 'n' bins, then there will be 'n+1' cuts / borders for that column,
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which will be output in sorted order from lowest to highest.
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Different columns can have different numbers of bins according to their range.
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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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# DMatrix is not quantized right away, but will be once a hist model is generated
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model <- xgb.train(
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data = dm,
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params = list(tree_method = "hist", max_bin = 8, nthread = 1),
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nrounds = 3
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)
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# Now can get the quantile cuts
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xgb.get.DMatrix.qcut(dm)
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}
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