R/create_leaderdyadyears.R

In peacesciencer: Tools and Data for Quantitative Peace Science Research

#' Create leader-dyad-years from the Archigos data
#'
#' @description
#'
#' \code{create_leaderdyadyears()} allows you to created leader dyad-year data
#' from the Archigos data first introduced and described by Goemans et al.
#' (2009).
#'
#' @return
#'
#' \code{create_leaderdyadyears()} takes remote data available for separate
#' download and returns a complete leader dyad-year data frame for all leaders,
#' and all possible dyads, from 1870 to 2015.
#'
#' @details
#'
#' This is a *complete* and *universal* leader dyad-year data frame for all
#' possible dyadic leader pairings from 1870 to 2015. This has several
#' implications. First: these data are enormous. The output is over 2 million
#' rows long! Second: the time required to create these data from scratch would
#' take too long for a normal function call. This amounts to an unholy
#' combination of data that are too large for CRAN's disk space restrictions
#' (5 MB) and too time-consuming to do from scratch every time. Thus, the
#' data are pre-generated and stored remotely. Check [download_extdata()] for
#' more information.
#'
#' @author Steven V. Miller
#'
#' @references
#'
#' Goemans, Henk E., Kristian Skrede Gleditsch, and Giacomo Chiozza. 2009.
#' "Introducing Archigos: A Dataset of Political Leaders"
#' *Journal of Peace Research* 46(2): 269--83.
#'
#'
#' @param system a character specifying whether the user wants Correlates of War
#' state-years ("cow") or Gleditsch-Ward ("gw") state-years. Gleditsch-Ward is the
#' default.
#' @param directed optional, defaults to TRUE. If TRUE, the function returns
#' so-called "directed" leader dyad-year data. If FALSE, the function returns
#' non-directed data where the state codes for the second leader are all greater
#' than the state codes for the second leader.
#'
#' @examples
#' \dontrun{
#' # download_extdata()
#' # ^ make sure you've run this first.
#' # default is directed
#' create_leaderdyadyears()
#'
#' # non-directed
#' create_leaderdyadyears(directed = FALSE)
#' }
#'
create_leaderdyadyears <- function(directed = TRUE, system = "gw") {

  if (!(system %in% c("cow", "gw"))) {
    stop("create_leaderdyadyears() requires the system argument to be either 'cow' (Correlates of War) or 'gw' (Gleditsch-Ward). Default is 'gw'.")

  }

  if (!file.exists(system.file("extdata", "gw_dir_leader_dyad_years.rds", package="peacesciencer"))) {

    stop("The process of creating these data would take too long for a normal function. Thus, they are pre-generated, stored remotely, and must be downloaded separately.\nThis error disappears after successfully running `download_extdata()`. Thereafter, the function works with no problem.")

  } else {

    if (system == "gw") {

      readRDS(system.file("extdata", "gw_dir_leader_dyad_years.rds", package="peacesciencer")) -> data

      if (directed == FALSE) {

        data %>%
          filter(.data$gwcode1 < .data$gwcode2) -> data

      }
    } else { # Assuming it's CoW.

      readRDS(system.file("extdata", "cow_dir_leader_dyad_years.rds", package="peacesciencer")) -> data

      if (directed == FALSE) {

        data %>%
          filter(.data$ccode1 < .data$ccode2) -> data

      }

    }





  }

  attr(data, "ps_data_type") = "leader_dyad_year"
  if (system == "cow") {
    attr(data, "ps_system") = "cow"
  } else {
    attr(data, "ps_system") = "gw"
  }

  return(data)

}