Sandbox/Old object possibilities/dual.formula.R

In akreutzmann/trafo: Estimation, Comparison and Selection of Transformations

#' #' Dual Formula
#' #'
#' #' Dual estimation 
#' #' @param formula object of type formula with the model to transform
#' #' @param data an optional data frame containing the variables in the model 
#' #' @param \dots additional arguments to be passed to the estimation function; see dualEst()
#' #' @return an object of class \code{transformation}; see dualEst()
#' #' @keywords internal
#' #' @export
#' dual.formula <- function(formula, data = list(), ...){
#'   model_frame <- model.frame(formula = formula, data = data)
#'   if (is.null(y <- model.response(model_frame)))
#'     stop("Dependent variable y must not be empty")
#'   if (is.null(x <- model.matrix(attr(model_frame,"terms"), data = model_frame))) 
#'     stop("Matrix of covariates X must not be empty")
#'   if (any(y <= 0)) 
#'     stop("response variable must be positive")
#'   dualEst(y,x)
#' }