R/fetch_indicator.R

In worldbank/pddcs: Prepare data for Data Collection System

#' Fetch indicator
#'
#' Fetch data for a specified indicator from available sources.
#'
#' `r lifecycle::badge("stable")`
#'
#' See `?indicatorlist` for an overview of available indicators.
#'
#' @param indicator character: A CETS type indicator code. See details.
#' @param source character: Data source.
#' @return tibble
#' @examples
#' \dontrun{
#' # Fetch population data from Eurostat
#' df <- fetch_indicator("SP.POP.TOTL", source = "eurostat")
#'
#' # Fetch population data from UNPD
#' df <- fetch_indicator("SP.POP.TOTL", source = "unpd")
#'
#' # Fetch bed nets data from UNICEF
#' df <- fetch_indicator("SH.MLR.NETS.ZS", source = "unicef")
#'
#' # Fetch multiple indicators from the same source
#' df <- fetch_indicator(
#'   indicator = c("SH.STA.ANV4.ZS", "SN.ITK.VITA.ZS"),
#'   source = "unicef"
#' )
#'
#' # Fetch multiple indicators from different sources
#' df <- fetch_indicator(
#'   indicator = c("SH.STA.ANV4.ZS", "SP.POP.TOTL"),
#'   source = c("unicef", "eurostat")
#' )
#' }
#' @export
fetch_indicator <- function(indicator, source) {

  # Repeat source if length is 1
  if (length(source) == 1) {
    source <- rep(source, length(indicator))
  }

  # Check that lengths match
  if (length(indicator) != length(source)) {
    rlang::abort(
      "`source` must either be of length 1 or have the same length as `indicator`."
    )
  }

  # Fetch data
  dl <- purrr::map2(indicator, source, .f = fetch_indicator_single)

  # Combine to data frame
  df <- data.table::rbindlist(dl)

  # Convert to tibble
  df <- dplyr::tibble(df)

  return(df)
}

#' Fetch indicator (single)
#'
#' @inheritParams fetch_indicator
#' @keywords internal
fetch_indicator_single <- function(indicator,
                                   source = c(
                                     "eurostat", "unicef",
                                     "unpd", "who"
                                   )) {
  # Match argument
  source <- match.arg(source)

  # Check inputs
  check_inputs_fetch_indicator(indicator, source)

  # Fetch data
  df <- fetch_data(indicator, source)

  return(df)
}

#' fetch_data
#' @inheritParams fetch_indicator
#' @return data.frame
#' @noRd
fetch_data <- function(indicator, source) {

  # Fetch data, based on source
  if (source == "eurostat") {
    df <- fetch_eurostat(indicator)
  }
  if (source == "unpd") {
    df <- fetch_unpd(indicator)
  }
  if (source == "unicef") {
    df <- fetch_unicef(indicator)
  }
  if (source == "who") {
    df <- fetch_who(indicator)
  }

  # Add source column
  df$source <- source

  return(df)
}

#' check_inputs_fetch_indicator
#' @inheritParams fetch_indicator
#' @return logical
#' @noRd
check_inputs_fetch_indicator <- function(indicator, source) {
  if (!source %in% c("eurostat", "unpd", "who", "unicef")) {
    rlang::abort(sprintf("`%s` is not a valid source.", source))
  }

  if (source == "eurostat") {
    if (!indicator %in% eurostat_indicators) {
      rlang::abort(sprintf("`%s` is not a valid indicator for Eurostat.", indicator))
    }
  }

  if (source == "unpd") {
    if (!indicator %in% unpd_indicators) {
      rlang::abort(sprintf("`%s` is not a valid indicator for UN Population Division.", indicator))
    }
  }

  if (source == "who") {
    if (!indicator %in% who_indicators) {
      rlang::abort(sprintf("`%s` is not a valid indicator for WHO GHO.", indicator))
    }
  }

  if (source == "unicef") {
    if (!indicator %in% unicef_indicators) {
      rlang::abort(sprintf("`%s` is not a valid indicator for UNICEF.", indicator))
    }
  }
}