R/spq_group_by.R

In lvaudor/glitter: glitter makes SPARQL

#' Group the results by one or more variables
#' @param .query query
#' @param ... Either R-DSL or strings with variable names
#' @return A query object
#' @export
#' @examples
#' spq_init() %>%
#' spq_add("?item wdt:P361 wd:Q297853") %>%
#' spq_add("?item wdt:P1082 ?folkm_ngd") %>%
#' spq_add("?area wdt:P31 wd:Q1907114") %>%
#' spq_label(area) %>%
#' spq_add("?area wdt:P527 ?item") %>%
#' spq_group_by(area, area_label)  %>%
#' spq_summarise(total_folkm = sum(folkm_ngd))
spq_group_by = function(.query, ...) {

  vars = purrr::map_chr(rlang::enquos(...), spq_treat_argument)

  purrr::reduce(
    vars,
    function(query, x) track_structure(query, name = x, grouping = TRUE),
    .init = .query
  )

}