R/download_fars.R

In rfars: Download and Analyze Crash Data

#' (Internal) Download FARS data files
#'
#' Download files from NHTSA, unzip, and prepare them.
#'
#' @param years Years to be downloaded, in yyyy (character or numeric formats)
#' @param dest_raw Directory to store raw CSV files
#' @param dest_prepd Directory to store prepared CSV files
#' @param states (Optional) Inherits from get_fars()
#'
#' @return Nothing directly to the current environment. Various CSV files are stored either in a temporary directory or dir as specified by the user.
#'
#' @details Raw files are downloaded from \href{https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/}{NHTSA}.


download_fars <- function(years,
                          dest_raw,
                          dest_prepd,
                          states){

  for(y in years){

    dest_zip   <- tempfile() # creates and stores the name for where the zip file will be downloaded to

    dest_raw_y <- paste0(dest_raw, "/", y)

    my_url <- paste0(
      "https://static.nhtsa.gov/nhtsa/downloads/FARS/", y,
      "/National/FARS", y,
      "NationalSAS.zip")

    try_my_url <- try(
      expr = downloader::download(my_url, destfile=dest_zip, mode="wb"),
      silent = TRUE)

    if(inherits(try_my_url, "try-error")){

      message(paste0("Failed to download data for year ", y))
      next

    } else{

      cat(paste0("\u2713 ", y, " data downloaded\n"))

    # Unzip and remove zipfiles
      utils::unzip(dest_zip, exdir = dest_raw_y, overwrite = TRUE)
      unlink(dest_zip)

    # File structure changes
      if(y %in% c(2011:2015, 2020)){

        from <- paste0(dest_raw_y, "/FARS", y, "NationalSAS") %>% list.files(full.names = T, recursive = T)

        to <- gsub(x = from, pattern = paste0("/FARS", y, "NationalSAS"), replacement = "")

        dir.create(paste0(dest_raw_y, "/format-32"), showWarnings = F)
        dir.create(paste0(dest_raw_y, "/format-64"), showWarnings = F)

        file.copy(from, to, overwrite = T)

        unlink(paste0(dest_raw_y, "/FARS", y, "NationalSAS"), recursive = T)

      }


    if(y %in% c(2021:2022)){

        from <- paste0(dest_raw_y, "/FARS", y, "NationalSAS") %>% list.files(full.names = T, recursive = T)

        to <- gsub(x = from, pattern = paste0("/FARS", y, "NationalSAS"), replacement = "")

        dir.create(paste0(dest_raw_y, "/format-viya"), showWarnings = F)

        file.copy(from, to, overwrite = T)

        unlink(paste0(dest_raw_y, "/FARS", y, "NationalSAS"), recursive = T)

      }


    # Get list of raw data files
      rawfiles <-
        #data.frame(filename = list.files(dest_raw_y, recursive = T, full.names = T)) %>%
        data.frame(filename = list.files(dest_raw_y, recursive = T)) %>%
        #filter(stringr::str_detect(filename, "sas7bdat"))
        dplyr::mutate(
          type = stringr::word(.data$filename, start = -1, end = -1, sep = stringr::fixed(".")) %>% stringr::str_to_upper(),
          cleaned  = .data$filename %>%
            stringr::str_to_lower() %>%
            stringr::str_remove(".csv") %>%
            stringr::str_remove(".sas7bdat") %>%
            stringr::str_remove(".sas7bcat") %>%
            stringr::str_remove(".sas") %>%
            stringr::str_remove(".txt") %>%
            stringr::word(-1, sep="/")
          ) %>%
        filter(stringr::str_to_upper(.data$type) %in% c("SAS7BDAT", "SAS"))


    # Fix dest_raw_y, dest_prepd
      if(substr(dest_raw_y, nchar(dest_raw_y), nchar(dest_raw_y)) != "/") dest_raw_y <- paste0(dest_raw_y, "/")
      if(substr(dest_prepd, nchar(dest_prepd), nchar(dest_prepd)) != "/") dest_prepd <- paste0(dest_prepd, "/")


    # Prep each file, producing annual CSVs
      prep_fars(
        y=y,
        wd = dest_raw_y,
        rawfiles = rawfiles,
        prepared_dir = dest_prepd,
        states = states
        )


    # Compile the full codebook
      full_codebook <-
        dir(dest_raw, pattern = "codebook.rds", recursive=TRUE, full.names=TRUE) %>%
        map_dfr(readRDS) %>%
        distinct()

      saveRDS(full_codebook, paste0(dest_prepd, "codebook.rds"))

      cat(paste0("\u2713 ", "Codebook file saved in ", dest_prepd, "\n"))

    }

    }

}