R/add_ccode_to_gw.R

In peacesciencer: Tools and Data for Quantitative Peace Science Research

#' Add Correlates of War state system codes to your data with Gleditsch-Ward
#' state codes.
#'
#' @description
#'
#' \code{add_ccode_to_gw()} allows you to match, as well as one can, Correlates
#' of War system membership data with Gleditsch-Ward system data.
#'
#'
#' @return
#'
#' \code{add_ccode_to_gw()} takes a (dyad-year, leader-year, leader-dyad-year,
#' state-year) data frame that already has Gleditsch-Ward state system codes and
#' adds their corollary Correlates of War codes.
#'
#' @details
#'
#' As of version 1.2, this function leans on the information made available in
#' the \pkg{isard} package. This is a spin-off package I maintain for data that
#' require periodic updates for the functionality in this package. As of writing,
#' \pkg{peacesciencer} only requires that you have the \pkg{isard} package
#' installed. It does not require you to have any particular version of the
#' package installed. Thus, what exactly this function returns may depend on the
#' particular version of \pkg{isard} you have installed. This will assuredly
#' concern the right-bound of the temporal domain of data you get.
#'
#' You can read more about the data in the documentation for \pkg{isard}.
#'
#' - [https://svmiller.com/isard/reference/gw_cw_panel.html](https://svmiller.com/isard/reference/gw_cw_panel.html)
#'
#' The user will invariably need to be careful and ask why they want these data
#' included. The issue here is that both have a different composition and the
#' merging process will not (and cannot) be perfect. We can note that a case
#' like Gran Colombia is not too difficult to handle (i.e. CoW does not have
#' this entity and none of the splinter states conflict with CoW's coding).
#' However, there is greater weirdness with a case like the unification of West
#' Germany and East Germany. Herein, Correlates of War treats the unification as
#' the reappearance of the original Germany whereas Gleditsch-Ward treat the
#' unification as an incorporation of East Germany into West Germany. The script
#' will *not* create state-year or dyad-year duplicates for the Gleditsch-Ward
#' codes. The size of the original data remain unchanged. However, there will be
#' some year duplicates for various Correlates of War codes (prominently Serbia
#' and Yugoslavia in 2006). Use with care.
#'
#' You can also use the \pkg{countrycode} package. Whether you use this function
#' or the \pkg{countrycode} package, do *not* do this kind of merging without
#' assessing the output.
#'
#' @author Steven V. Miller
#'
#' @param data a data frame with appropriate \pkg{peacesciencer} attributes
#'
#'
#' @examples
#' \donttest{
#' # just call `library(tidyverse)` at the top of the your script
#' library(magrittr)
#'
#' create_dyadyears(system = "gw") %>% add_ccode_to_gw()
#'
#' create_stateyears(system = 'gw') %>% add_ccode_to_gw()
#' }
#'


add_ccode_to_gw <- function(data) {

  if (any(i <- c("ccode1", "ccode2", "ccode") %in% colnames(data))) {

    stop("Your data already appear to have Correlates of War state codes in it.")

  }

  if (length(attributes(data)$ps_system) == 0 | attributes(data)$ps_system != "gw") {
    warning("The state system data here do not appear to be Gleditsch-Ward, or at least not declared as such. The function will still run, but you may want to inspect the output.")

  }

  ps_type <- attr(data, "ps_data_type")

  dispatch <- list(
    state_year = .add_ccode_to_gw_state_year,
    leader_year = .add_ccode_to_gw_state_year,
    dyad_year = .add_ccode_to_gw_dyad_year,
    leader_dyad_year = .add_ccode_to_gw_dyad_year
  )

  if (!ps_type %in% names(dispatch)) {

    stop("Unsupported ps_data_type. Data type must be 'dyad_year', `leader_dyad_year`, 'leader_year', or 'state_year'.")

  }

  data <- dispatch[[ps_type]](data)

  return(data)

}


#' @keywords internal
#' @noRd
.add_ccode_to_gw_state_year <- function(data) {

  # state-year panel; G-W is master and we want CoW codes. ----
  syp <- isard::gw_cw_panel

  syp %>% select(.data$gwcode, .data$ccode, .data$year) -> hold_this

  if (!all(i <- c("gwcode") %in% colnames(data))) {

    stop("add_ccode_to_gw() merges on the Gleditsch-Ward code, which your data don't have right now. Make sure to run create_stateyears(system = 'gw') at the top of the pipe.")


  } else {

    data %>%
      left_join(., hold_this,
                by = c("gwcode" = "gwcode",
                       "year" = "year")) -> data

  }

}

#' @keywords internal
#' @noRd
.add_ccode_to_gw_dyad_year <- function(data) {

  # state-year panel; G-W is master and we want CoW codes. ----
  syp <- isard::gw_cw_panel

  syp %>% select(.data$gwcode, .data$ccode, .data$year) -> hold_this

  if (!all(i <- c("gwcode1", "gwcode2") %in% colnames(data))) {

    stop("add_cow_to_gwcode() merges on two Gleditsch-Ward codes (gwcode1, gwcode2), which your data don't have right now. Make sure to run create_dyadyears() at the top of the pipe. You'll want the default option, which returns Correlates of War codes.")


  } else {

    data %>%
      left_join(., hold_this, by=c("gwcode1"="gwcode", "year"="year")) %>%
      rename(ccode1 = .data$ccode) %>%
      left_join(., hold_this, by=c("gwcode2"="gwcode", "year"="year")) %>%
      rename(ccode2 = .data$ccode) -> data

  }

}





# aadd_ccode_to_gw <- function(data) {
#
#   if (any(i <- c("ccode1", "ccode2", "ccode") %in% colnames(data))) {
#
#     stop("Your data already appear to have Correlates of War state codes in it.")
#
#   }
#
#   if (length(attributes(data)$ps_system) == 0 | attributes(data)$ps_system != "gw") {
#     warning("The state system data here do not appear to be Gleditsch-Ward, or at least not declared as such. The function will still run, but you may want to inspect the output.")
#
#   }
#
#   # state-year panel; G-W is master and we want CoW codes. ----
#
#   syp <- isard::gw_cw_panel
#
#   syp %>% select(.data$gwcode, .data$ccode, .data$year) -> hold_this
#
#   if (length(attributes(data)$ps_data_type) > 0 && attributes(data)$ps_data_type %in% c("dyad_year", "leader_dyad_year")) {
#
#     if (!all(i <- c("gwcode1", "gwcode2") %in% colnames(data))) {
#
#       stop("add_cow_to_gwcode() merges on two Gleditsch-Ward codes (gwcode1, gwcode2), which your data don't have right now. Make sure to run create_dyadyears() at the top of the pipe. You'll want the default option, which returns Correlates of War codes.")
#
#
#     } else {
#
#       data %>%
#         left_join(., hold_this, by=c("gwcode1"="gwcode", "year"="year")) %>%
#         rename(ccode1 = .data$ccode) %>%
#         left_join(., hold_this, by=c("gwcode2"="gwcode", "year"="year")) %>%
#         rename(ccode2 = .data$ccode) -> data
#
#       return(data)
#
#     }
#
#
#
#   } else if (length(attributes(data)$ps_data_type) > 0 && attributes(data)$ps_data_type %in% c("state_year", "leader_year")) {
#
#     if (!all(i <- c("gwcode") %in% colnames(data))) {
#
#       stop("add_ccode_to_gw() merges on the Gleditsch-Ward code, which your data don't have right now. Make sure to run create_stateyears(system = 'gw') at the top of the pipe.")
#
#
#     } else {
#
#       data %>%
#         left_join(., hold_this) -> data
#
#       return(data)
#
#     }
#
#   } else  {
#     stop("add_ccode_to_gw() requires a data/tibble with attributes$ps_data_type of state_year or dyad_year. Try running create_dyadyears() or create_stateyears() at the start of the pipe.")
#   }
#
#   return(data)
# }