R/search.R

In rerddap: General Purpose Client for 'ERDDAP' Servers

#' Search for ERDDAP tabledep or griddap datasets
#'
#' @export
#'
#' @param query (character) Search terms
#' @param page (integer) Page number
#' @param page_size (integer) Results per page
#' @param which (character) One of tabledep or griddap.
#' @param url A URL for an ERDDAP server. Default:
#' https://upwell.pfeg.noaa.gov/erddap/ - See [eurl()] for 
#' more information
#' @param ... Curl options passed on to [crul::verb-GET] (must be
#' named parameters)
#' @references https://upwell.pfeg.noaa.gov/erddap/index.html
#' @examples \dontrun{
#' (out <- ed_search(query='temperature'))
#' out$alldata[[1]]
#' (out <- ed_search(query='size'))
#' out$info
#'
#' # List datasets
#' ed_datasets('table')
#' ed_datasets('grid')
#'
#' # use a different ERDDAP server
#' ## Marine Institute (Ireland)
#' ed_search("temperature", url = "http://erddap.marine.ie/erddap/")
#' }

ed_search <- function(query, page=NULL, page_size=NULL, which='griddap',
                      url = eurl(), ...){

  check_arg(query, "character")
  check_arg(page, "numeric")
  check_arg(page_size, "numeric")
  which <- match.arg(which, c("tabledap","griddap"), FALSE)
  args <- rc(list(searchFor = query, page = page, itemsPerPage = page_size))
  json <- erdddap_GET(paste0(url, 'search/index.json'), args, ...)
  colnames <- vapply(
    tolower(json$table$columnNames), function(z) gsub("\\s", "_", z),
    "", USE.NAMES = FALSE)
  dfs <- lapply(json$table$rows, function(x){
    names(x) <- colnames
    x <- x[c('title','dataset_id')]
    data.frame(x, stringsAsFactors = FALSE)
  })
  df <- data.frame(rbindlist(dfs))
  lists <- lapply(json$table$rows, stats::setNames, nm = colnames)
  df$gd <- vapply(
    lists, function(x) {
      if (x$griddap == "") "tabledap" else "griddap"
    }, character(1))
  df <- df[ df$gd == which, -3 ]
  row.names(df) <- NULL
  res <- list(info = df, alldata = lists)
  structure(res, class = "ed_search")
}

#' @export
print.ed_search <- function(x, ...){
  print(tibble::as_tibble(x$info))
}

#' @export
#' @rdname ed_search
ed_datasets <- function(which = 'tabledap', url = eurl()){
  which <- match.arg(which, c("tabledap","griddap"), FALSE)
  url <- sprintf('%s%s/index.json', url, which)
  out <- erdddap_GET(url, list(page = 1, itemsPerPage = 10000L))
  nms <- out$table$columnNames
  lists <- lapply(out$table$rows, stats::setNames, nm = nms)
  tibble::as_tibble(rbindlist(lapply(lists, data.frame,
                                         stringsAsFactors = FALSE)))
}