52 lines
2.3 KiB
R
52 lines
2.3 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.DataIter}
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\alias{xgb.DataIter}
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\title{XGBoost Data Iterator}
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\usage{
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xgb.DataIter(env = new.env(), f_next, f_reset)
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}
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\arguments{
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\item{env}{An R environment to pass to the callback functions supplied here, which can be
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used to keep track of variables to determine how to handle the batches.
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For example, one might want to keep track of an iteration number in this environment in order
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to know which part of the data to pass next.}
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\item{f_next}{\verb{function(env)} which is responsible for:\itemize{
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\item Accessing or retrieving the next batch of data in the iterator.
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\item Supplying this data by calling function \link{xgb.DataBatch} on it and returning the result.
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\item Keeping track of where in the iterator batch it is or will go next, which can for example
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be done by modifiying variables in the \code{env} variable that is passed here.
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\item Signaling whether there are more batches to be consumed or not, by returning \code{NULL}
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when the stream of data ends (all batches in the iterator have been consumed), or the result from
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calling \link{xgb.DataBatch} when there are more batches in the line to be consumed.
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}}
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\item{f_reset}{\verb{function(env)} which is responsible for reseting the data iterator
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(i.e. taking it back to the first batch, called before and after the sequence of batches
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has been consumed).
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Note that, after resetting the iterator, the batches will be accessed again, so the same data
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(and in the same order) must be passed in subsequent iterations.}
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}
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\value{
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An \code{xgb.DataIter} object, containing the same inputs supplied here, which can then
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be passed to \link{xgb.ExternalDMatrix}.
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}
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\description{
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Interface to create a custom data iterator in order to construct a DMatrix
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from external memory.
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This function is responsible for generating an R object structure containing callback
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functions and an environment shared with them.
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The output structure from this function is then meant to be passed to \link{xgb.ExternalDMatrix},
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which will consume the data and create a DMatrix from it by executing the callback functions.
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For more information, and for a usage example, see the documentation for \link{xgb.ExternalDMatrix}.
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}
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\seealso{
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\link{xgb.ExternalDMatrix}, \link{xgb.DataBatch}.
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}
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