convert S4 to S3; add some extra methods to DMatrix

R-package/man/dimnames.xgb.DMatrix.Rd

@@ -0,0 +1,36 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/xgb.DMatrix.R
+\name{dimnames.xgb.DMatrix}
+\alias{dimnames.xgb.DMatrix}
+\alias{dimnames<-.xgb.DMatrix}
+\title{Handling of column names of \code{xgb.DMatrix}}
+\usage{
+\method{dimnames}{xgb.DMatrix}(x)
+
+\method{dimnames}{xgb.DMatrix}(x) <- value
+}
+\arguments{
+\item{x}{object of class \code{xgb.DMatrix}}
+
+\item{value}{a list of two elements: the first one is ignored
+and the second one is column names}
+}
+\description{
+Only column names are supported for \code{xgb.DMatrix}, thus setting of 
+row names would have no effect and returnten row names would be NULL.
+}
+\details{
+Generic \code{dimnames} methods are used by \code{colnames}.
+Since row names are irrelevant, it is recommended to use \code{colnames} directly.
+}
+\examples{
+data(agaricus.train, package='xgboost')
+train <- agaricus.train
+dtrain <- xgb.DMatrix(train$data, label=train$label)
+dimnames(dtrain)
+colnames(dtrain)
+colnames(dtrain) <- make.names(1:ncol(train$data))
+print(dtrain, verbose=TRUE)
+
+}
+