new nrow function for xgb.DMatrix

R-package/NAMESPACE

@@ -16,6 +16,7 @@ export(xgb.save)
 export(xgb.save.raw)
 export(xgb.train)
 export(xgboost)
+exportMethods(nrow)
 exportMethods(predict)
 import(methods)
 importClassesFrom(Matrix,dgCMatrix)
@@ -52,4 +53,3 @@ importFrom(stringr,str_match)
 importFrom(stringr,str_replace)
 importFrom(stringr,str_split)
 importFrom(stringr,str_trim)
-import(vcd)

R-package/R/nrow.xgb.DMatrix.R

@@ -0,0 +1,18 @@
+setGeneric("nrow")
+
+#' @param x Object of class \code{xgb.DMatrix}
+#' @title \code{nrow} return the number of rows present in x.
+#' @rdname nrow
+#' @examples
+#' data(agaricus.train, package='xgboost')
+#' train <- agaricus.train
+#' dtrain <- xgb.DMatrix(train$data, label=train$label)
+#' stopifnot(nrow(dtrain) == nrow(train$data))
+#' 
+#' @export
+setMethod("nrow",
+          signature = "xgb.DMatrix",
+          definition = function(x) {
+            xgb.numrow(x)
+          }
+)

R-package/man/nrow.Rd

@@ -0,0 +1,22 @@
+% Generated by roxygen2 (4.1.0): do not edit by hand
+% Please edit documentation in R/nrow.xgb.DMatrix.R
+\docType{methods}
+\name{nrow,xgb.DMatrix-method}
+\alias{nrow,xgb.DMatrix-method}
+\title{\code{nrow} return the number of rows present in x.}
+\usage{
+\S4method{nrow}{xgb.DMatrix}(x)
+}
+\arguments{
+\item{x}{Object of class \code{xgb.DMatrix}}
+}
+\description{
+\code{nrow} return the number of rows present in x.
+}
+\examples{
+data(agaricus.train, package='xgboost')
+train <- agaricus.train
+dtrain <- xgb.DMatrix(train$data, label=train$label)
+stopifnot(nrow(dtrain) == nrow(train$data))
+}
+