b4d97d3cb8
* [R] better argument check in xgb.DMatrix; fixes #1480 * [R] showsd was a dummy; fixes #2044 * [R] better categorical encoding explanation in vignette; fixes #1989 * [R] new roxygen version docs update
86 lines
3.3 KiB
R
86 lines
3.3 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.attr}
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\alias{xgb.attr}
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\alias{xgb.attr<-}
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\alias{xgb.attributes}
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\alias{xgb.attributes<-}
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\title{Accessors for serializable attributes of a model.}
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\usage{
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xgb.attr(object, name)
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xgb.attr(object, name) <- value
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xgb.attributes(object)
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xgb.attributes(object) <- value
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}
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\arguments{
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\item{object}{Object of class \code{xgb.Booster} or \code{xgb.Booster.handle}.}
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\item{name}{a non-empty character string specifying which attribute is to be accessed.}
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\item{value}{a value of an attribute for \code{xgb.attr<-}; for \code{xgb.attributes<-}
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it's a list (or an object coercible to a list) with the names of attributes to set
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and the elements corresponding to attribute values.
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Non-character values are converted to character.
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When attribute value is not a scalar, only the first index is used.
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Use \code{NULL} to remove an attribute.}
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}
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\value{
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\code{xgb.attr} returns either a string value of an attribute
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or \code{NULL} if an attribute wasn't stored in a model.
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\code{xgb.attributes} returns a list of all attribute stored in a model
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or \code{NULL} if a model has no stored attributes.
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}
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\description{
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These methods allow to manipulate the key-value attribute strings of an xgboost model.
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}
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\details{
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The primary purpose of xgboost model attributes is to store some meta-data about the model.
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Note that they are a separate concept from the object attributes in R.
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Specifically, they refer to key-value strings that can be attached to an xgboost model,
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stored together with the model's binary representation, and accessed later
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(from R or any other interface).
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In contrast, any R-attribute assigned to an R-object of \code{xgb.Booster} class
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would not be saved by \code{xgb.save} because an xgboost model is an external memory object
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and its serialization is handled externally.
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Also, setting an attribute that has the same name as one of xgboost's parameters wouldn't
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change the value of that parameter for a model.
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Use \code{\link{xgb.parameters<-}} to set or change model parameters.
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The attribute setters would usually work more efficiently for \code{xgb.Booster.handle}
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than for \code{xgb.Booster}, since only just a handle (pointer) would need to be copied.
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That would only matter if attributes need to be set many times.
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Note, however, that when feeding a handle of an \code{xgb.Booster} object to the attribute setters,
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the raw model cache of an \code{xgb.Booster} object would not be automatically updated,
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and it would be user's responsibility to call \code{xgb.save.raw} to update it.
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The \code{xgb.attributes<-} setter either updates the existing or adds one or several attributes,
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but it doesn't delete the other existing attributes.
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}
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\examples{
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data(agaricus.train, package='xgboost')
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train <- agaricus.train
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bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
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eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic")
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xgb.attr(bst, "my_attribute") <- "my attribute value"
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print(xgb.attr(bst, "my_attribute"))
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xgb.attributes(bst) <- list(a = 123, b = "abc")
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xgb.save(bst, 'xgb.model')
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bst1 <- xgb.load('xgb.model')
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print(xgb.attr(bst1, "my_attribute"))
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print(xgb.attributes(bst1))
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# deletion:
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xgb.attr(bst1, "my_attribute") <- NULL
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print(xgb.attributes(bst1))
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xgb.attributes(bst1) <- list(a = NULL, b = NULL)
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print(xgb.attributes(bst1))
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}
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