R/xtset.r

In flynnzac/rata: An Imperative Library for Data Manipulation

## This file is part of genvar.

## genvar is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, under version 3 of the License.

## genvar is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.

## You should have received a copy of the GNU General Public License
## along with genvar.  If not, see <https://www.gnu.org/licenses/>.

#' prepares a panel dataset for lag operations
#'
#' prepares a panel dataset for lag operations.  The lag function in R is simply "lag(var,numlags)".  After calling \code{xtset}, this lag function will work on the panel in the way you would expect.
#' @param timevar the name of the variable to for the time dimension
#' @param obsvar the name of the variable to use for the observation dimension
#' @return returns NULL, invisibly
#' @examples
#' library(plm)
#' data(Produc)
#' use(Produc, clear=TRUE)
#' xtset(year, state)
#' gen(Lemp, L(emp))
#' listif(vars="emp Lemp")
#' reg(emp, unemp, effect="twoway")
#' reg(emp, unemp, effect="individual")
#' reg(emp, unemp, effect="time")
#' @importFrom "plm" pdata.frame
#' @export
xtset <- function (timevar, obsvar)
{
  timevar <- gvcharexpr(enquo(timevar))
  obsvar <- gvcharexpr(enquo(obsvar))
  assert_loaded()
  eval(substitute({data <- pdata.frame(data, index=c(obsvar,timevar))}),
       envir=data.env)
  eval(substitute({attr(data,"timevar") <- timevar}), envir=data.env)
  eval(substitute({attr(data, "obsvar") <- obsvar}), envir=data.env)
  postuse()
  invisible(NULL)
}