R/read_lat_lon_csv.R

In degauss-org/dht: A Collection of Functions to Assist Building DeGAUSS Containers

#' read in and format input file for DeGAUSS container
#'
#' @export
#' @param filename name of input file, probably opt$filename if inside container
#' @param nest_df logical. If TRUE, data is nested on lat/lon. Defaults to FALSE.
#' @param sf_out logical. If TRUE, data is converted as an sf object. Defaults to FALSE.
#' @param project_to_crs (optional) if sf_out=TRUE, the crs to which input data is projected. If unspecified
#'                       and sf_out=TRUE, the crs defaults to 4326.
#' @return a list with two elements. The first is the raw_data as it is read in from the input file.
#' The second is a tibble nested on lat and lon to prevent duplication of geomarker computations.
#' If sf_out=TRUE the second is an sf object.
#' @examples
#' \dontrun{
#' d <- read_lat_lon_csv(filename = "test/my_address_file_geocoded.csv")
#' d <- read_lat_lon_csv(
#'   filename = "test/my_address_file_geocoded.csv",
#'   sf_out = TRUE, project_to_crs = 5072
#' )
#' }
#'
read_lat_lon_csv <- function(filename, nest_df = FALSE, sf_out = FALSE, project_to_crs = NULL) {
  cli::cli_alert_info("loading input file...", wrap = TRUE)

  raw_data <-
    readr::read_csv(
      filename,
      col_types = readr::cols(
        lat = readr::col_double(),
        lon = readr::col_double()
      )
    )

  raw_data$.row <- seq_len(nrow(raw_data))

  if (nest_df) {
    d <-
      raw_data %>%
      dplyr::select(.row, lat, lon) %>%
      stats::na.omit() %>%
      dplyr::group_by(lat, lon) %>%
      tidyr::nest(.rows = c(.row))

    if (sf_out) {
      if (!requireNamespace("sf", quietly = TRUE)) {
        stop("reading input data as an sf object requires the sf package; install that first")
      }
      cli::cli_alert_info("converting input to sf object...", wrap = TRUE)
      d <- sf::st_as_sf(d, coords = c("lon", "lat"), crs = 4326)

      if (!is.null(project_to_crs)) {
        cli::cli_alert_info("projecting input...", wrap = TRUE)
        d <- sf::st_transform(d, project_to_crs)
      }
    }
    return(list(raw_data = raw_data, d = d))
  }

  return(raw_data)
}