# -----------------------------------------------------------------------------
# FUNCTIONS: get.dummy get.dummies
# Retrieve the dummy variables for a data.frame
# -----------------------------------------------------------------------------
#' Get the dummy variable columns from a data frame.
#'
#' Given a data.frame and an optional variables name, return only the columns
#' that are dummy variables
#'
#' This uses \code{\link{which.dummy}} to identify the dummy columns.
#'
#' @param data A data.frame with an dummies attributes
#' @param name Optional. The name of a variable.
#' @return The subset of \code{data} that are dummy columns.
#' @author Christopher Brown
#' @seealso \code{\link{which.dummy}}, \code{\link{dummy.data.frame}}
#' @keywords manip
#' @examples
#'
#'
#' data( iris )
#' d <- dummy.data.frame( iris )
#' get.dummy( d, 'Species' )
#'
#'
get.dummy <- function(data,name=NULL) {
if( ! is.null(name) ) {
dat <- data[ , which.dummy(data, name) ]
} else {
dat <- data[ , which.dummy(data) ]
}
return(dat)
}
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