R/lightcurves_data_dl.R

In samuelmacedo83/exoplanets: Exoplanets

#' lightcurves_data_dl
#'
#' Download the lightcurve data according to the kepid provided
#'
#' @param kepid_table A data frame containing a column name kepid
#'
#' @importFrom magrittr %>%
#' @export
lightcurves_data <- function(kepid_table){

 #verify if lightcurves folder exists, if not, creates
  if (!dir.exists("lightcurves")){
    dir.create("lightcurves")
  }

  # when the user doesn't pass a data.frame
  if (class(kepid_table) == "numeric"){

    kepid_table = data.frame(kepid = kepid_table)
  }

 # verify the kepid column
 if (!any(grepl("kepid", names(kepid_table))) == TRUE){
   stop("There is no kepid column in your data")
 }


# remove duplicate
kepid_table <- kepid_table %>%
  dplyr::select(kepid) %>%
  dplyr::distinct()

# padronizing the star name by nine digits. "000847632"
kepid_table <-  purrr::map_chr(kepid_table$kepid,
                               stringr::str_pad,
                               width = 9, pad = "0")

# kepler lightcurve website
base_url <- "http://archive.stsci.edu/pub/kepler/lightcurves/"

# downloading lightcurves
purrr::walk(kepid_table, download_lightcurve,
           base_url = base_url)

}

download_lightcurve <- function(kepid, base_url){


  # star lightcurve url
  kepid_url <- paste0(base_url,
                      substring(kepid, 1, 4), "/",
                      kepid, "/")

  # Link to download lightcurve data
  kepid_html <- xml2::read_html(kepid_url)
  kepid_fits <- kepid_html %>% rvest::html_nodes("a") %>% rvest::html_text()
  kepid_lc <- purrr::map_lgl(kepid_fits, grepl, pattern ="_lc_")
  kepid_tar <- kepid_fits[kepid_lc]



  # Create the folder to storage the data, in necessary
  kepid_folder <- paste0("lightcurves/",kepid)

  if (dir.exists(kepid_folder)) {
    cat(paste0("The ", kepid, " lightcurve directory already exists\n"))
  }  else {
    utils::download.file(url = paste0(kepid_url, kepid_tar),
                         destfile = "lightcurves/temp.tar",
                         method = "curl",
                         quiet = TRUE)
    utils::untar("lightcurves/temp.tar",
                 exdir = "lightcurves")

    file.remove("lightcurves/temp.tar")

    cat(paste0("The ", kepid, " lightcurve was successfully downloaded\n"))
  }

}