R/stl_as_sf.R

In chris-prener/stlData: City of St. Louis Data

#' Load tibble as sf
#'
#' @description For specified tibbles, this function will load them as simple features with appropriate
#'     geometric data.
#'
#' @details This function currently works with the tibbles that contain census tract level data:
#'     stl_tbl_asthma, stl_tbl_income, stl_tbl_insurance, stl_tbl_lead, and stl_tbl_smoking
#'
#' @param table Unquoted name of one of the accepted tables
#'
#' @return A simple features object with the specified tibble joined to the appropriate geometry.
#'
#' @importFrom dplyr %>%
#' @importFrom dplyr left_join
#' @importFrom dplyr select
#' @importFrom dplyr rename
#'
#' @export
stl_as_sf <- function(table) {

  # To prevent NOTE from R CMD check 'no visible binding for global variable'
  AWATER = COUNTYFP = FUNCSTAT = GEOID = INTPTLAT = INTPTLON = MTFCC = NAME = NAMELSAD =
    STATEFP = TRACTCE = NULL

  # quote input
  tblQ <- rlang::quo_name(rlang::enquo(table))

  if (requireNamespace("sf", quietly = TRUE)) {

    # create list of acceptable tables
    tableList <- c("stl_tbl_asthma", "stl_tbl_income", "stl_tbl_insurance",
                   "stl_tbl_lead", "stl_tbl_pop", "stl_tbl_race", "stl_tbl_smoking")

    # compare input with list of tables
    if (!!tblQ %nin% tableList) {
      stop("The given table is not available for automatic conversion to an sf object.")
    }

    tracts <- get("stl_sf_tracts")

    # merge data
    merge <- left_join(tracts, table, by = c("GEOID" = "geoID"))

    # clean up merge
    merge %>%
      select(-STATEFP, -COUNTYFP, -TRACTCE, -NAME, -NAMELSAD, -MTFCC, -FUNCSTAT, -AWATER,
             -INTPTLAT, -INTPTLON) %>%
      rename(geoID = GEOID) -> merge

    test <- class(merge)[1]

    if (test != "sf"){

      stop("The package sf must be loaded prior to executing this function.")

    }

    # return output
    return(merge)

  } else {

    stop("The package sf is required for this function but not found.")

  }

}