#' Download and create a data.table of CRU CL v. 2.0 climatology elements
#'
#' This function automates downloading and importing \acronym{CRU}
#' \acronym{CL} v. 2.0 climatology data and creates a \CRANpkg{data.table} of
#' the data. If requested, minimum and maximum temperature may also be
#' automatically calculated as described in the data
#' [readme.txt](https://crudata.uea.ac.uk/cru/data/hrg/tmc/readme.txt) file.
#' Data may be cached for later use by this function, saving time downloading
#' files in future use of this function.
#'
#' @section Nomenclature and Units:
#' \describe{
#' \item{pre}{precipitation (millimetres/month)}
#' \describe{
#' \item{cv}{cv of precipitation (percent)}
#' }
#' \item{rd0}{wet-days (number days with >0.1 millimetres rain per month)}
#' \item{tmp}{mean temperature (degrees Celsius)}
#' \item{dtr}{mean diurnal temperature range (degrees Celsius)}
#' \item{reh}{relative humidity (percent)}
#' \item{sunp}{sunshine (percent of maximum possible (percent of day length))}
#' \item{frs}{ground-frost (number of days with ground-frost per month)}
#' \item{wnd}{10 metre windspeed (metres/second)}
#' \item{elv}{elevation (automatically converted to metres)}
#' }
#' For more information see the description of the data provided by
#' \acronym{CRU}, <https://crudata.uea.ac.uk/cru/data/hrg/tmc/readme.txt>
#'
#' @param pre Fetches precipitation (millimetres/month) from server and
#' returns it in the data frame, `TRUE`. Defaults to `FALSE`.
#' @param pre_cv Fetch cv of precipitation (percent) from server and
#' returns it in the data frame, `TRUE`. Defaults to `FALSE`. NOTE Setting
#' this to `TRUE` will always results in **pre** being set to `TRUE` and
#' returned as well.
#' @param rd0 Fetches wet-days (number days with >0.1 millimetres rain
#' per month) and returns it in the data frame? Defaults to `FALSE`.
#' @param dtr Fetches mean diurnal temperature range (degrees Celsius)
#' and returns it in the data frame? Defaults to `FALSE`.
#' @param tmp Fetches temperature (degrees Celsius) and returns it in the
#' data frame, `TRUE`. Defaults to `FALSE`.
#' @param tmn Calculates minimum temperature values (degrees Celsius)
#' and returns it in the data frame, `TRUE`. Defaults to `FALSE`.
#' @param tmx Calculates maximum temperature (degrees Celsius) and
#' returns it in the data frame, `TRUE`. Defaults to `FALSE`.
#' @param reh Fetches relative humidity and returns it in the data frame,
#' `TRUE`. Defaults to FALSE.
#' @param sunp Fetch sunshine, percent of maximum possible (percent of
#' day length) and return it in the data frame? Defaults to `FALSE`.
#' @param frs Fetches ground-frost records (number of days with ground-
#' frost per month) and return it in the data frame? Defaults to `FALSE`.
#' @param wnd Fetches 10m wind speed (metres/second) and returns it in the
#' data frame, `TRUE`. Defaults to `FALSE`.
#' @param elv Fetches elevation (converted to metres) and returns it in
#' the data frame, `TRUE`. Defaults to `FALSE`.
#' @param cache Stores CRU CL v. 2.0 data files locally for later use.
#' If `FALSE`, the downloaded files are removed when the \R session is closed.
#' To take advantage of cached files in future sessions, use `cache = TRUE`
#' even after the initial download and caching. Defaults to `FALSE`.
#'
#' @examplesIf interactive()
#' # Download data and create a data frame of precipitation and temperature
#' # without caching the data files
#' CRU_pre_tmp <- get_CRU_df(pre = TRUE, tmp = TRUE)
#'
#' head(CRU_pre_tmp)
#' CRU_pre_tmp
#'
#' @seealso
#' [create_CRU_stack], [manage_cache].
#'
#' @inherit create_CRU_df author
#' @inherit create_CRU_df source
#' @inherit create_CRU_df references
#' @inherit create_CRU_df return
#'
#' @export
get_CRU_df <- function(pre = FALSE,
pre_cv = FALSE,
rd0 = FALSE,
tmp = FALSE,
dtr = FALSE,
reh = FALSE,
tmn = FALSE,
tmx = FALSE,
sunp = FALSE,
frs = FALSE,
wnd = FALSE,
elv = FALSE,
cache = FALSE) {
.check_vars_FALSE(
pre,
pre_cv,
rd0,
tmp,
dtr,
reh,
tmn,
tmx,
sunp,
frs,
wnd,
elv
)
cache_dir <- .set_cache(cache)
files <- .get_CRU(
pre,
pre_cv,
rd0,
tmp,
dtr,
reh,
tmn,
tmx,
sunp,
frs,
wnd,
elv,
cache_dir
)
return(.create_df(tmn, tmx, tmp, dtr, pre, pre_cv, elv, files))
}
#' @export
#' @rdname get_CRU_df
get_cru_df <- get_CRU_df
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