R/pdynmc_fitMethods.R

In markusfritsch/pdynmc: Moment Condition Based Estimation of Linear Dynamic Panel Data Models

#####################################################
###	Version information
#####################################################

###
###	Starting point
###

#	AhnSchmidt_Nonlinear_2017-11-07.R

#	split into different functions as of code version
#	AhnSchmidt_Nonlinear_2019-04-08.R





















##################################################################################
###	Define residuals, fitted, predict, print, and summary methods for class 'pdynmc'
##################################################################################











#' Case and Variable Names of Fitted Model.
#'
#' \code{case.names} extracts variable names of cross-sectional and
#'    longitudinal identifiers of an object of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return A list containing tow character vectors with the variable
#'    names of the cross-sectional and the longitudinal identifiers
#'    from object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats case.names
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' case.names(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  case.names(m1)
#' }
#'
#'
case.names.pdynmc <- function(object, ...){

  cn.pd <- list("cross-section id" = as.character(unique(object$data$dat.na[ , object$data$varname.i])),
                "longitudinal id" = as.character(unique(object$data$dat.na[ , object$data$varname.t])))

  return(cn.pd)
}













#' Extract Coefficient Estimates of Fitted Model.
#'
#' \code{coef.pdynmc} extracts coefficient estimates of an object
#'    of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return Extract coefficient estimates from object of class
#'    `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' coef(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  coef(m1)
#' }
#'
#'
coef.pdynmc <- function(object, ...){

  coef.pd <- object$coefficients

  return(coef.pd)
}















#' Extract Coefficient Estimates of Time Dummies of Fitted Model.
#'
#' \code{dummy.coef.pdynmc} extracts coefficient estimates of
#'    time dummies of an object of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return Extract coefficient estimates of time dummies from
#'    object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats dummy.coef
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' dummy.coef(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  dummy.coef(m1)
#' }
#'
#'
dummy.coef.pdynmc		<- function(object, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }
  if(length(object$data$varnames.dum) == 1 &&  object$data$varnames.dum == "no time dummies"){
    stop("No time dummies included in estimation.")
  }

  dum.pd <- object$coefficients[object$data$varnames.reg %in% object$data$varnames.dum]

  return(dum.pd)
}
















#' Extract Fitted Values of Fitted Model.
#'
#' \code{fitted.pdynmc} extracts fitted values of an object of class
#'    `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param step An integer denoting the iteration step for which
#'    fitted values are extracted (defaults to last iteration step
#'    used for obtaining parameter estimates).
#' @param na.rm A logical variable indicating whether missing values
#'    should be removed from the vector of fitted values (defaults
#'    to `FALSE`).
#' @param ... further arguments.
#'
#' @return Extract fitted values from object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats na.omit
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' fitted(m1, na.rm = TRUE)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  fitted(m1, na.rm = TRUE)
#' }
#'
#'
fitted.pdynmc		<- function(object, step = object$iter, na.rm = FALSE, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  if(na.rm == TRUE){
    fit.pd	<- stats::na.omit(get(paste("step", step, sep = "") , object$fitted.values))
  } else{
    fit.pd	<- get(paste("step", step, sep = "") , object$fitted.values)
  }
  return(fit.pd)
}































#' Extract Instrument Matrix of Fitted Model.
#'
#' \code{model.matrix.pdynmc} extracts instrument matrix of an
#'    object of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param sparse Whether to return a sparse matrix (if set to 'TRUE')
#'    or a regular matrix (if set to 'FALSE').
#' @param ... further arguments.
#'
#' @return Extracts instrument matrix from an object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' model.matrix(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  model.matrix(m1)
#' }
#'
#'
model.matrix.pdynmc		<- function(object, sparse = TRUE, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  if(sparse == TRUE){
    modmat <- object$data$Z.temp
  } else{
    modmat <- as.matrix(do.call(what = rbind, object$data$Z.temp, ...))
  }
  return(modmat)
}














#' Extract Instrument Count of Fitted Model.
#'
#' \code{ninst} is a generic function fo extracting the instrument
#'    count of an object.
#'
#' @param object An object for which the instrument count is desired.
#' @param ... further arguments.
#'
#' @return Extracts instrument count from an object.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' ninst(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  ninst(m1)
#' }
#'
#'
ninst <- function(object, ...){
  UseMethod("ninst", object)
}


#' Extract Instrument Count of Fitted Model.
#'
#' \code{ninst.pdynmc} extracts instrument count of an object of
#'    class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return Extracts instrument count from an object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' ninst(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  ninst(m1)
#' }
#'
#'
ninst.pdynmc		<- function(object, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  ninsts <- object$data$n.inst

  return(ninsts)
}

















#' Extract Number of Observations of Fitted Model.
#'
#' \code{nobs.pdynmc} extracts number of observations in cross-section
#'    dimension and longitudinal dimension of an object of class
#'    `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return Extracts number of observations in cross-section dimension
#'    and longitudinal dimension of an object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats nobs
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' nobs(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  nobs(m1)
#' }
#'
#'
nobs.pdynmc		<- function(object, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  nob.i <- object$data$n
  nob.t <- object$data$Time

  cat("Cross-section dimension ", paste("n = ", nob.i, sep = ""), "\n", sep = "")
  cat("longitudinal dimension ", paste("n = ", nob.t, sep = ""), "\n", sep = "")
}


















#' Extract Input Parameters of Numeric Optimization of Fitted Model.
#'
#' \code{optimIn} is a generic function for extracting input parameters
#'    of numeric optimization for an object.
#'
#' @param object An object for which input parameters of numeric
#'    optimization are desired.
#' @param ... further arguments.
#'
#' @return \code{optimIn} extracts input parameters used in numeric
#'    optimization from object.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' optimIn(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "BFGS")
#'  optimIn(m1)
#' }
#'
#'
optimIn <- function(object, ...){
  UseMethod("optimIn", object)
}


#' Extract Input Parameters of Numeric Optimization of Fitted Model.
#'
#' \code{optimIn.pdynmc} extracts input parameters of numeric
#'    optimization for an object of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param step An integer denoting the iteration step for which input
#'    parameters are extracted (defaults to last iteration step used
#'    for obtaining parameter estimates).
#' @param ... further arguments.
#'
#' @return Extracts input parameters of numeric optimization from
#'    object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' optimIn(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "BFGS")
#'  optimIn(m1)
#' }
#'
#'
optimIn.pdynmc		<- function(object, step = object$iter, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  if(object$data$opt.method == "none"){
    ret <- paste("No parameter inputs can be extracted (no numerical optimization carried out).")
  } else {
    ret	<- get(paste("step", step, sep = "") , object$ctrl.optim, ...)
    return(ret)
  }
}
















#' Plot Coefficient Estimates and Corresponding Ranges of Fitted Model.
#'
#' \code{plot.pdynmc} Plot methods for objects of class `pdynmc`. The
#'    available plot options visualize: Fitted values versus residuals,
#'    coefficient ranges across GMM iterations, coefficient paths and
#'    objective function values across GMM iterations as proposed by
#'    \insertCite{HanLee2020inference;textual}{pdynmc}.
#'
#' @param x An object of class `pdynmc`. The function requires
#'    twostep or iterative GMM estimates.
#' @param type Whether to plot fitted values against residuals (argument
#'    'fire'; default), first differenced fitted values against
#'    first differenced residuals (argument 'fire.fd'),
#'    coefficient ranges (argument 'coef.range';
#'    this requires twostep or iterative GMM estimates), path of
#'    coefficient estimates across GMM iterations (argument 'coef.path';
#'    this requires twostep or iterative GMM estimates).
#' @param include.dum Include estimates of parameters corresponding to time
#'    dummies (defaults to 'black'; requires 'type = coef.range').
#' @param include.fur.con Include estimates of parameters corresponding to
#'    further controls (defaults to 'FALSE'; requires 'type = coef.range').
#' @param col.coefRange Specify color for plotting range of coefficient
#'    estimates (defaults to 'NULL'; requires 'type = coef.range').
#' @param col.coefInitial Specify color for plotting initial coefficient
#'    estimates (defaults to 'darkgrey'; requires 'type = coef.range').
#' @param col.coefEst Specify color for plotting coefficient estimate
#'    (defaults to 'royalblue'; requires 'type = coef.range').
#' @param omit1step Omit coefficient estimates from one-step GMM
#'    estimation in coefficient range plot. The argument can be employed
#'    to exclude the randomly drawn starting values from the plotted
#'    coefficient range when coefficient estimates were obtained from
#'    numerical optimization methods (defaults to `FALSE`). Set to `TRUE`
#'    to exert the option; this argument requires iterative GMM estimates
#'    and argument 'type = coef.range'.
#' @param boxplot.coef Whether to draw boxplots for coefficient estimates
#'    (defaults to 'FALSE'); requires iterative GMM with at least 10
#'    iterations and argument 'type = coef.range'. Proceed with caution
#'    as this argument is experimental.
#' @param co Character string denoting the variable name(s) for which to
#'    plot the path of coefficient estimate(s) across GMM iterations
#'    (defaults to 'NULL') as proposed in \insertCite{HanLee2020inference;textual}{pdynmc};
#'    if no coefficient name is given, all coefficient paths are plotted;
#'    requires at least two iterations and argument 'type = coef.path'.
#' @param add.se.approx A logical variable indicating if standard errors
#'    should be added to the plot of the path of coefficient estimate(s)
#'    across GMM iterations (defaults to 'NULL'); requires at least
#'    two iterations and argument 'type = coef.path'. This option is
#'    only available when plotting a single coefficient path (i.e.,
#'    when 'co' contains only a single variable name).
#' @param conf.lev A numeric variable indicating the confidence
#'    level for approximating standard errors in the plot of the path
#'    of coefficient estimate(s) across GMM iterations (defaults to
#'    0.95; sensible values lie in the interval ]0,1[); requires
#'    argument 'type = coef.path' and argument 'add.se.approx = TRUE'.
#' @param ... further arguments.
#'
#' @return Plot fitted values against residuals ('type = fire') or
#'    coefficient estimates and coefficient estimate ranges
#'    ('type = coef.range') for object of class `pdynmc`. The latter
#'    plot requires twostep or iterative GMM estimates.
#'
#' @author Markus Fritsch and Joachim Schnurbus
#' @export
#' @importFrom graphics abline
#' @importFrom graphics axis
#' @importFrom graphics boxplot
#' @importFrom graphics legend
#' @importFrom graphics lines
#' @importFrom graphics plot
#' @importFrom graphics points
#' @importFrom grDevices colorRampPalette
#' @importFrom stats qnorm
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @references
#' \insertAllCited{}
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "twostep",
#'     opt.meth = "none")
#' plot(m1)
#' plot(m1, type = "coef.range")
#' plot(m1, type = "coef.path")
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "iterative",
#'     opt.meth = "none")
#'  plot(m1)
#'  plot(m1, type = "coef.range")
#'  plot(m1, type = "coef.path")
#' }
#'
#'
plot.pdynmc		<- function(
  x
  ,type = "fire"
  ,include.dum = FALSE
  ,include.fur.con = FALSE
  ,col.coefRange = 1
  ,col.coefInitial = "darkgrey"
  ,col.coefEst = "royalblue"
  ,omit1step = FALSE
  ,boxplot.coef = FALSE
  ,co = NULL
  ,add.se.approx = NULL
  ,conf.lev = 0.95
  ,...
){

  if(type == "fire"){

    if(!inherits(x, what = "pdynmc")){
      stop("Use only with \"pdynmc\" objects.")
    }

    step.temp <- x$iter
    fitteds <- unlist(x$fitted.values.int[[step.temp]])     #fitted values in levels
    resids  <- unlist(x$residuals.int[[step.temp]])         #residuals in levels

    y.range	<- c(-1, 1)*max(abs(resids))
    graphics::plot(x = fitteds, y = resids, ylim = y.range, xlab = "Fitted values", ylab = "Residuals",
#         main	= paste("Fitted vs. residual plot of", substitute(x))
         , col = "grey60", ...)
    graphics::lines(x = c(par("usr")[1], par("usr")[2]), y = c(0,0), col = 1, lty = 2)
#    graphics::lines(x = range(fitteds, na.rm = TRUE), y = c(0,0), col = 1, lty = 2)
#    graphics::abline(h = 0)
  }

  if(type == "fire.fd"){

    if(!inherits(x, what = "pdynmc")){
      stop("Use only with \"pdynmc\" objects.")
    }

    step.temp <- x$iter
    fitteds <- unlist(x$fitted.values[[step.temp]])       #fitted values in first differences
    resids  <- unlist(x$residuals[[step.temp]])           #residuals in first differences

    y.range	<- c(-1, 1)*max(abs(resids))
    graphics::plot(x = fitteds, y = resids, ylim = y.range, xlab = "Fitted values", ylab = "Residuals",
                   #         main	= paste("Fitted vs. residual plot of", substitute(x))
                   , col = "grey60", ...)
    graphics::lines(x = c(par("usr")[1], par("usr")[2]), y = c(0,0), col = 1, lty = 2)
    #    graphics::lines(x = range(fitteds, na.rm = TRUE), y = c(0,0), col = 1, lty = 2)
    #    graphics::abline(h = 0)
  }


  if(type == "coef.range"){
    if(!inherits(x, what = "pdynmc")){
      stop("Use only with \"pdynmc\" objects.")
    }
    if(x$iter == 1){
      stop("Only onestep estimates available; plot requires twostep or iterated GMM results.")
    }
    if(boxplot.coef == TRUE && x$iter < 10){
      boxplot.coef <- FALSE
      warning("Argument 'boxplot.coef' was ignored as coefficient boxplots are only displayed for a minimum of 10 iterations.")
    }

    if(x$iter == 2 & omit1step){
      stop("Cannot compute range from two-step GMM estimates after removing one-step estmates.")
    }

    parMar <- par()$mar
    par(mar=par()$mar + c(0,0,0,8), xpd=TRUE)

    if(!include.dum | !include.fur.con){
      if(!include.dum && !include.fur.con){
        varnames.ind <- !(x$data$varnames.reg %in% x$data$varnames.dum) & !(x$data$varnames.reg %in% x$data$varnames.reg.fur)
      } else{
        if(!include.dum){
          varnames.ind <- !(x$data$varnames.reg %in% x$data$varnames.dum)
        } else{
          varnames.ind <- !(x$data$varnames.reg %in% x$data$varnames.reg.fur)
        }
      }
    } else{
      varnames.ind <- rep(TRUE, times = length(x$data$varnames.reg))
    }
    var.names <- x$data$varnames.reg[varnames.ind]

    n.iter    <- x$iter
    if(x$data$opt.method == "none"){
      coef.list <- lapply(x$par.clForm, FUN = '[', varnames.ind)
    } else{
      coef.list <- lapply(x$par.optim, FUN = '[', varnames.ind)
    }
    coef.est  <- x$coefficients[varnames.ind]
    n.coef    <- length(coef.est)

    coef.mat  <- do.call(what = cbind, coef.list)
    if(omit1step){
      coef.mat <- coef.mat[,-1]
    }

    if(nrow(coef.mat) == 1){
      if(boxplot.coef){
        graphics::plot(x = rep(n.coef, times = 2), y = c(coef.mat.min, coef.mat.max), type = "n", xaxt = "n", xlab = "", ylab = "", ...)
        graphics::points(x = n.coef, y = coef.mat[,1], col = col.coefInitial, pch = 1, ...)
        graphics::boxplot(t(coef.mat), xaxt = "n", xlabel = "", ylabel = "", ...)

      } else{
        coef.mat.min <- min(coef.mat)
        coef.mat.max <- max(coef.mat)
        graphics::plot(x = rep(n.coef, times = 2), y = c(coef.mat.min, coef.mat.max), type = "n", xaxt = "n", xaxt = "n", xlab = "", ylab = "", ...)
        graphics::lines(x = rep(n.coef, times = 2), y = c(coef.mat.min, coef.mat.max), col = col.coefRange, lwd = 1, lty = 2, ...)
        graphics::points(x = n.coef, y = coef.mat[,1], col = col.coefInitial, pch = 1, ...)
        graphics::points(x = n.coef, y = coef.est, col = col.coefEst, pch = 18, ...)
        graphics::axis(side = 1, at = c(1:n.coef), labels = paste(var.names))
      }
    } else{
      if(boxplot.coef){
        graphics::boxplot(t(coef.mat), xaxt = "n", xlabel = "", ylabel = "Estimate", ...)
        for(i in 1:n.coef){
          graphics::points(x = x.vec[i], y = coef.mat[i,1], col = col.coefInitial, pch = 1, ...)
          graphics::lines(x = c(i-0.2, i+0.2), y = rep(coef.est[i], times = 2), col = col.coefEst, lwd = 2, ...)
        }
      } else{
        coef.mat.min.max <- cbind(apply(X = coef.mat, MARGIN = 1, FUN = min), apply(X = coef.mat, MARGIN = 1, FUN = max))
        x.vec        <- 1:n.coef
        graphics::plot(x = rep(x.vec, each = 2), y = t(coef.mat.min.max), type = "n", xlim = c(0.7, n.coef+0.3), xaxt = "n", xaxt = "n", xlab = "", ylab = "Estimate", ...)
        for(i in 1:n.coef){
          graphics::lines(x = rep(x.vec[i], times = 2), y = coef.mat.min.max[i,], col = col.coefRange, lwd = 1, lty = 2, ...)
          graphics::points(x = x.vec[i], y = coef.mat[i,1], col = col.coefInitial, pch = 1, ...)
          graphics::points(x = x.vec[i], y = coef.est[i], col = col.coefEst, pch = 18, ...)
        }
        graphics::axis(side = 1, at = c(1:n.coef), labels = paste(var.names))
      }
    }
#    abline(h = 0)
#    graphics::legend("bottomleft", col = c(col.coefEst, col.coefInitial, col.coefRange), lwd = c(NA,NA,1), pch = c(18,1,NA), lty = c(NA,NA,2), legend = c("coeff. est.", "coeff. initial", "coeff. range"), bty = "n")
    graphics::legend("topright", inset = c(-0.35,0),
#      x = n.coef + 1, y = max(coef.mat),
                   legend = c("coef. est.", "coef. initial", "coef. range"), col = c(col.coefEst, col.coefInitial, col.coefRange),
                   lwd = c(NA,NA,1), pch = c(18,1,NA), lty = c(NA,NA,2), bty = "n", cex = 0.9, horiz = FALSE)
    par(mar = parMar)
  }




  if(type == "coef.path"){
    if(!inherits(x, what = "pdynmc")){
      stop("Use only with \"pdynmc\" objects.")
    }
    parMar <- par()$mar
    par(mar = par()$mar + c(0, 0, 0, 8), xpd = TRUE)
    if (is.null(co)) {
      if(!include.dum | !include.fur.con){
        if(!include.dum && !include.fur.con){
          varnames.ind <- !(x$data$varnames.reg %in% x$data$varnames.dum) & !(x$data$varnames.reg %in% x$data$varnames.reg.fur)
        } else {
          if (!include.dum) {
            varnames.ind <- !(x$data$varnames.reg %in% x$data$varnames.dum)
          } else {
            varnames.ind <- !(x$data$varnames.reg %in% x$data$varnames.reg.fur)
          }
        }
      } else {
        varnames.ind <- rep(TRUE, times = length(x$data$varnames.reg))
      }
      co <- x$data$varnames.reg[varnames.ind]
    }
    if(length(co) == 1 & sum(add.se.approx, is.null(add.se.approx))){
      add.se.approx <- TRUE
      plot.se <- TRUE
    } else {
      plot.se <- FALSE
      if(length(co) > 1 & sum(add.se.approx)){
        warning("Argument 'add.se.approx' is only available when plotting one coefficient path and was set to 'FALSE'")
      }
    }
    col.pal <- c(col.coefEst, col.coefInitial)
    coef.est <- if(sum(!is.na(x$par.optim[[x$iter]])) > 0) { x$par.optim } else { x$par.clForm }
    coef.mat <- Reduce(rbind, coef.est)[, x$data$varnames.reg %in% co]
    quant <- abs(stats::qnorm(p = (1 - conf.lev)/2, mean = 0, sd = 1))
    se.est <- x$stderr
    se.mat <- Reduce(rbind, se.est)[, x$data$varnames.reg %in% co]
    if(length(co) > 1){
      col.set <- (grDevices::colorRampPalette(col.pal))(length(co) + 1)
    } else {
      col.set <- col.pal
      coef.mat <- as.matrix(coef.mat, ncol = 1)
      se.mat <- as.matrix(se.mat, ncol = 1)
    }
    coef.range <- range(coef.mat, coef.mat[nrow(coef.mat), ] + quant * se.mat[nrow(se.mat), ], coef.mat[nrow(coef.mat), ] - quant * se.mat[nrow(se.mat), ])
    ord.min <- min(coef.range)
    ord.max <- max(coef.range)
#      if(sum(!is.na(x$par.optim[[x$iter]])) > 0){
#        objective <- matrix(data = unlist(x[["ctrl.optim"]]),nrow = length(x[["ctrl.optim"]]), byrow = TRUE, dimnames = list(NULL, names(x[["ctrl.optim"]][["step1"]])))
#        obj.values <- objective[, "value"]
#        obj.min <- min(obj.values)
#        obj.max <- max(obj.values)
#        a <- (ord.min * obj.max - ord.max * obj.min)/(obj.max - obj.min)
#        b <- (ord.max - ord.min)/(obj.max - obj.min)
#        obj.rescaled <- a + b * obj.values
#      } else {
#        obj.values <- NULL
#        ord.limits <- c(ord.min, ord.max)
#      }
    plot(x = rep(1:nrow(coef.mat), times = ncol(coef.mat)),
         y = coef.mat, xlab = "Iteration", ylab = "Estimate",
         xaxt = "n", xlim = c(1 - 0.25, nrow(coef.mat) +
                                0.25), ylim = coef.range, type = "n", main = paste("Coefficient estimates over ",
                                                                                   x$iter, " iterations", sep = ""))
    axis(side = 1, at = c(1:x$iter))
#     if (sum(!is.na(x$par.optim[[x$iter]])) > 0) {
#       graphics::lines(x = 1:nrow(coef.mat), y = obj.rescaled, type = "b", pch = 20, col = col.coefInitial)
#       graphics::axis(side = 4, at = c(ord.min, ord.max), labels = round(c(obj.min, obj.max), digits = 1),
#           col = col.set[length(col.set)], col.ticks = col.set[length(col.set)], col.lab = col.set[length(col.set)],
#           col.axis = col.set[length(col.set)])
#       graphics::mtext("Objective function value", side = 4, col = col.coefInitial)
#        }
    for(i in 1:ncol(coef.mat)){
      graphics::lines(x = 1:nrow(coef.mat), y = coef.mat[, i], type = "l", col = col.set[i])
      graphics::points(x = 1:nrow(coef.mat), y = coef.mat[, i], type = "b", pch = 19, col = col.set[i])
    }
    if(plot.se){
      graphics::lines(x = rep(nrow(coef.mat), times = 2),
                      y = c(coef.mat[nrow(coef.mat)] - quant * se.mat[nrow(coef.mat)], coef.mat[nrow(coef.mat)] + quant * se.mat[nrow(coef.mat)]),
                      type = "l", lty = 3, col = col.set[i])
      graphics::lines(x = c(nrow(coef.mat) - nrow(coef.mat)/20, nrow(coef.mat) + nrow(coef.mat)/20),
                      y = rep(coef.mat[nrow(coef.mat)] - quant * se.mat[nrow(coef.mat)], times = 2), type = "l",
                      lty = 1, col = col.set[i], lwd = 2)
      graphics::lines(x = c(nrow(coef.mat) - nrow(coef.mat)/20, nrow(coef.mat) + nrow(coef.mat)/20),
                      y = rep(coef.mat[nrow(coef.mat)] + quant * se.mat[nrow(coef.mat)], times = 2), type = "l",
                      lty = 1, col = col.set[i], lwd = 2)
    }
    graphics::legend("topright", inset = c(-0.35, 0), legend = co, col = col.set,
#		   if(sum(!is.na(x$par.optim[[x$iter]])) > 0){ c(co, "obj.fct") } else { co },
#			 if(sum(!is.na(x$par.optim[[x$iter]])) > 0){ c(col.set, col.coefInitial) } else { col.set },
      pch = 19, lty = 1, bty = "n", cex = 0.9, horiz = FALSE)
    par(mar = parMar)
  }
}

























#' Print Fitted Model Object.
#'
#' \code{print.pdynmc} prints objects of class `pdynmc`.
#'
#' @param x An object of class `pdynmc`.
#' @param digits An integer indicating the maximum number of digits to
#'    display in the object.
#' @param ... further arguments.
#'
#' @return Print objects of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats coef
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' m1
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  m1
#' }
#'
#'
#'
print.pdynmc	<- function(x, digits = max(3, getOption("digits") - 3), ...){

  if(!inherits(x, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  cat("\nDynamic linear panel estimation", paste(" (", x$data$estimation, ")", sep = ""), sep = "")
  cat("\nMoment conditions: ", paste(if(x$data$diffMC){ "linear (DIF)" }, if(x$data$levMC){ " linear (LEV)" }, if(x$data$nlMC){ " nonlinear" }), sep = "")
  cat("\nEstimation steps: ", paste(x$iter), sep = "")
  cat("\n")
  cat("\nCoefficients:\n")
  print.default(format(coef(x), digits = digits), print.gap = 2L, quote = FALSE)
  cat("\n")
}
















#' Print Summary of Fitted Model Object.
#'
#' \code{print.summary.pdynmc} prints the summary for objects of class
#'    `pdynmc`.
#'
#' @param x An object of class `summary.pdynmc`.
#' @param digits An integer indicating the maximum number of digits to
#'    display in the object.
#' @param signif.stars Argument is defined as in \code{\link{options}}.
#' @param ... further arguments.
#'
#' @return Print information on objects of class `summary.pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats coef
#' @importFrom stats printCoefmat
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' summary(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  summary(m1)
#' }
#'
#'
print.summary.pdynmc	<- function(x, digits = max(3, getOption("digits") - 3), signif.stars = getOption("show.signif.stars"), ...){

  if(!inherits(x, what = "summary.pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  #  cat(formula(paste(x$data$varname.y, paste(x$data$varnames.reg, collapse = "+"), sep = " ~ ")))
  #  cat("\n")
  cat("\nDynamic linear panel estimation", paste(" (", x$data$estimation, ")", sep = ""), sep = "")
#  cat("\nMoment conditions: ", paste(if(x$data$diffMC){paste(x$data$n.inst["inst.diff"], " linear (DIF)", sep = "") }, if(x$data$levMC){paste(" ", x$data$n.inst["inst.lev"], " linear (LEV)", sep = "") }, if(x$data$nlMC){paste(" ", x$data$n.inst["inst.nl"], " nonlinear", sep = "") }), sep = "")
  cat("\nGMM estimation steps: ", paste(x$iter), "\n", sep = "")
  cat("\nCoefficients:\n")
  printCoefmat(coef(x), digits = digits, signif.stars = signif.stars, na.print = "NA", ...)
  #  cat(paste("Total Sum of Squares ", round(x$tss, digits = digits), "\n", sep = ""))
  #  cat(paste("Residual Sum of Squares ", round(x$rss, digits = digits), "\n", sep = ""))
  cat("\n", paste(sum(x$data$n.inst), " total instruments are employed to estimate ", length(x$data$varnames.reg), " parameters", sep = ""))
  cat("\n", paste(if(x$data$diffMC){paste(x$data$n.inst["inst.diff"], " linear (DIF) ", sep = "") }, if(x$data$levMC){paste(x$data$n.inst["inst.lev"], " linear (LEV) ", sep = "") }, if(x$data$nlMC){paste(x$data$n.inst["inst.nl"],  " nonlinear", sep = "") }, sep = ""))
  cat("\n", paste(if(x$data$varnames.fur.con[1] == "no further controls"){"no further controls "} else {paste(if("inst.furCon.diff" %in% names(x$data$n.inst)){paste(x$data$n.inst["inst.furCon.diff"], " further controls (DIF) ", sep = "")}, if("inst.furCon.lev" %in% names(x$data$n.inst)){paste(x$data$n.inst["inst.furCon.lev"], " further controls (LEV) ", sep = "")}, sep = "")}, sep = ""))
  cat("\n", paste(if(x$data$varnames.dum[1] == "no time dummies"){"no time dummies "} else {paste(if("dum.diff" %in% names(x$data$n.inst)){paste(x$data$n.inst["dum.diff"], " time dummies (DIF) ", sep = "")}, if("dum.lev" %in% names(x$data$n.inst)){paste(x$data$n.inst["dum.lev"], " time dummies (LEV) ", sep = "")}, sep = "")}, sep = ""))

  cat("\n", "\nJ-Test (overid restrictions): ", paste(round(x$hansenj$statistic, digits = 2), " with ", x$hansenj$parameter, " DF, pvalue: ", if(x$hansenj$p.value < 0.001){paste("<0.001")} else{round(x$hansenj$p.value, digits = digits)}, sep = ""))
  cat("\nF-Statistic (slope coeff): ", paste(round(x$slopef$statistic, digits = 2), " with ", x$slopef$parameter, " DF, pvalue: ", if(x$slopef$p.value < 0.001){paste("<0.001")} else{round(x$slopef$p.value, digits = digits)}, sep = ""))
  cat("\nF-Statistic (time dummies): ", if(length(x$time.dumf) == 1){ "no time dummies included in estimation" } else{ paste(round(x$time.dumf$statistic, digits = 2), " with ", x$time.dumf$parameter, " DF, pvalue: ", if(x$time.dumf$p.value < 0.001){paste("<0.001")} else{round(x$time.dumf$p.value, digits = digits)}, sep = "")} )
  cat("\n")
}
















#' Extract Residuals of Fitted Model.
#'
#' \code{residuals.pdynmc} extracts residuals from an object of class
#'    `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param step An integer denoting the iteration step for which fitted
#'    values are extracted (defaults to last iteration step used for
#'    obtaining parameter estimates).
#' @param na.rm A logical variable indicating whether missing values
#'    should be removed from the vector of fitted values (defaults to
#'    `FALSE`).
#' @param ... further arguments.
#'
#' @return Extract residuals from object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats na.omit
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' residuals(m1, na.rm = TRUE)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#' ## Further code example
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  residuals(m1, na.rm = TRUE)
#' }
#'
#'
residuals.pdynmc		<- function(object, step = object$iter, na.rm = FALSE, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  if(na.rm == TRUE){
    res.pd	<- stats::na.omit(get(paste("step", step, sep = "") , object$residuals))
  } else{
    res.pd	<- get(paste("step", step, sep = "") , object$residuals)
  }
  return(res.pd)
}




















#' Summary for Fitted Model Object.
#'
#' \code{summary.pdynmc} generates the summary for objects of class
#'    `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return Object of class `summary.pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' summary(m1, na.rm = TRUE)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  summary(m1)
#' }
#'
#'
summary.pdynmc	<- function(object, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  step		<- object$iter
  est			<- object$data$estimation
  object$n.obs	<- object$data$n * object$data$n - length(object$data$dat.na[is.na(object$data$dat.na[, object$data$varname.y]), ])
  object$unbal	<- length(object$data$dat.na[is.na(object$data$dat.na[, object$data$varname.y]), ]) > 0

  coef.est		  <- as.numeric(if(object$data$opt.method == "none"){ get(paste("step", step, sep = ""), object$par.clForm)} else{get(paste("step", step, sep = ""), object$par.optim)})
  varnames.reg	<- object$data$varnames.reg

  stderr		<- get(paste("step", step, sep = ""), object$stderr)
  zvalue		<- get(paste("step", step, sep = ""), object$zvalue)
  pvalue		<- get(paste("step", step, sep = ""), object$pvalue)

  object$coefficients			<- cbind(coef.est, stderr, zvalue, pvalue)
  colnames(object$coefficients)	<- if(object$data$stderr.type != "corrected") {c("Estimate", "Std.Err", "z-value", "Pr(>|z|)")} else{c("Estimate", "Std.Err.rob", "z-value.rob", "Pr(>|z.rob|)")}
  rownames(object$coefficients)	<- object$data$varnames.reg

  object$hansenj		<- jtest.fct(object)

  object$slopef		  <- wald.fct(param = "slope", object = object)
  if(length(object$data$varnames.dum) > 1){
    object$time.dumf	<- wald.fct(param = "time.dum", object = object)
  } else{
    if(object$data$varnames.dum == "no time dummies"){
      object$time.dumf	<- "no times dummies included in estimation"
    } else{
      object$time.dumf	<- wald.fct(param = "time.dum", object = object)
    }
  }

  class(object)		<- "summary.pdynmc"
  return(object)
}






















#' Extract Names of Explanatory Variables of Fitted Model.
#'
#' \code{variable.names.pdynmc} extracts explanatory variables
#'    from an object of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param ... further arguments.
#'
#' @return Extract explanatory variables from an object of class
#'    `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#' @importFrom stats variable.names
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' variable.names(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  variable.names(m1)
#' }
#'
#'
variable.names.pdynmc		<- function(object, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  vnames	<- object$data$varnames.reg
  return(vnames)
}













#' Extract Variance Covariance Matrix of Fitted Model.
#'
#' \code{vcov.pdynmc} extracts variance covariance matrix of the
#'    paramter estimates from an object of class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param step An integer denoting the iteration step for which
#'    fitted values are extracted (defaults to last iteration step
#'    used for obtaining parameter estimates).
#' @param ... further arguments.
#'
#' @return Extract variance covariance matrix of the parameter estimates
#'    from an object of class `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' vcov(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  vcov(m1)
#' }
#'
#'
vcov.pdynmc		<- function(object, step = object$iter, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  vcov	<- get(paste("step", step, sep = "") , object$vcov)
  return(vcov)
}


















#' Extract Weighting Matrix of Fitted Model.
#'
#' \code{wmat} is a generic function for extracting the
#'    weighting matrix of an object.
#'
#' @param object An object for which the weighting matrix is
#'    desired.
#' @param ... further arguments.
#'
#' @return Extract weighting matrix from an object.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' wmat(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  wmat(m1)
#' }
#'
#'
wmat <- function(object, ...){
  UseMethod("wmat", object)
}


#' Extract Weighting Matrix of Fitted Model.
#'
#' \code{wmat.pdynmc} extracts weighting matrix from an object of
#'    class `pdynmc`.
#'
#' @param object An object of class `pdynmc`.
#' @param step An integer denoting the iteration step for which
#'    fitted values are extracted (defaults to last iteration step
#'    used for obtaining parameter estimates).
#' @param ... further arguments.
#'
#' @return Extract weighting matrix from an object of class
#'    `pdynmc`.
#'
#' @author Markus Fritsch
#' @export
#'
#' @seealso
#'
#' \code{\link{pdynmc}} for fitting a linear dynamic panel data model.
#'
#' @examples
#' ## Load data
#' data(ABdata, package = "pdynmc")
#' dat <- ABdata
#' dat[,c(4:7)] <- log(dat[,c(4:7)])
#' dat <- dat[c(1:140), ]
#'
#' ## Code example
#' m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#' wmat(m1)
#'
#' \donttest{
#' ## Load data
#'  data(ABdata, package = "pdynmc")
#'  dat <- ABdata
#'  dat[,c(4:7)] <- log(dat[,c(4:7)])
#'
#'  m1 <- pdynmc(dat = dat, varname.i = "firm", varname.t = "year",
#'     use.mc.diff = TRUE, use.mc.lev = FALSE, use.mc.nonlin = FALSE,
#'     include.y = TRUE, varname.y = "emp", lagTerms.y = 2,
#'     fur.con = TRUE, fur.con.diff = TRUE, fur.con.lev = FALSE,
#'     varname.reg.fur = c("wage", "capital", "output"), lagTerms.reg.fur = c(1,2,2),
#'     include.dum = TRUE, dum.diff = TRUE, dum.lev = FALSE, varname.dum = "year",
#'     w.mat = "iid.err", std.err = "corrected", estimation = "onestep",
#'     opt.meth = "none")
#'  wmat(m1)
#' }
#'
#'
wmat.pdynmc		<- function(object, step = object$iter, ...){

  if(!inherits(object, what = "pdynmc")){
    stop("Use only with \"pdynmc\" objects.")
  }

  wmat	<- get(paste("step", step, sep = "") , object$w.mat, ...)
  return(wmat)
}