test_source/old scripts/get_croston.R

In opoyc/autoforecast: Forecast Development Kit

#' Fit Croston model
#'
#' @param .data Data frame or tibble with a response variable.
#' @param y_var String. Column name of the time series to be forecasted.
#' @param horizon Numeric. Number of periods to forecast.
#' @param parameter List. Parameter to be used for estimation, looks for alpha parameter.
#'
#' @import forecast
#' @import stats
#' @return data-frame
#' @export
#'
#' @examples
#' \dontrun{
#' get_croston()
#' }
get_croston <- function(.data, y_var, horizon = 12, parameter = NULL){
  if(is.null(attributes(.data)[["prescription"]]) == FALSE) {
    prescription <- attributes(.data)[["prescription"]]
    y_var <- prescription$y_var
    date_var <- prescription$date_var
    freq <- prescription$freq
    na_exclude <- unique(c(prescription$key, y_var, date_var))
  }
  # Ts object
  y_var_int <- ts(.data[[y_var]], frequency = freq)
  # Fit
  if(is.null(parameter)){
    model_fit <- croston(y_var_int, h = horizon)
  }else{
    model_fit <- croston(y_var_int, alpha = parameter[["croston"]][["alpha"]], h = horizon)
  }
  # Output
  .fit_output <- list(model = "croston"
                      , y_var_int = y_var_int
                      , model_fit = model_fit
                      , y_var_pred = as.numeric(model_fit$mean)
                      , parameter = list(alpha = ifelse(is.null(parameter$croston$alpha), 0.1 , parameter$croston$alpha))
  )
  attr(.fit_output, "prescription") <- prescription
  class(.fit_output) <- ".fit_output"
  return(.fit_output) 
}