R/dimensional_query_select_dimension.R

In geomultistar: Multidimensional Queries Enriched with Geographic Data

#' Select dimension
#'
#' To add a dimension in a `dimensional_query` object, we have to define its
#' name and a subset of the dimension attributes. If only the name of the
#' dimension is indicated, it is considered that all its attributes should be
#' added.
#'
#' @param dq A `dimensional_query` object.
#' @param name A string, name of the dimension.
#' @param attributes A vector of attribute names.
#'
#' @return A `dimensional_query` object.
#'
#' @family query functions
#'
#' @examples
#'
#' dq <- dimensional_query(ms_mrs) |>
#'   select_dimension(name = "where",
#'                   attributes = c("city", "state")) |>
#'   select_dimension(name = "when")
#'
#' @export
select_dimension <- function(dq,
                            name = NULL,
                            attributes = NULL) {
  UseMethod("select_dimension")
}



#' @rdname select_dimension
#' @export
select_dimension.dimensional_query <- function(dq,
                                              name = NULL,
                                              attributes = NULL) {
  stopifnot("The name of the dimension must be indicated." = !is.null(name))
  validate_names(names(dq$input$dimension), name, concept = 'dimension name')
  stopifnot("The dimension had already been selected." = !(name %in% names(dq$dimension)))
  stopifnot("There are repeated attributes." = length(attributes) == length(unique(attributes)))
  all_attributes <- names(dq$input$dimension[[name]])
  key <- all_attributes[1]
  attributes_defined <- all_attributes[-1]
  for (attribute in attributes) {
    validate_names(attributes_defined, attribute, concept = 'attribute')
  }
  if (is.null(attributes) |
      setequal(attributes, attributes_defined)) {
    attributes <- attributes_defined
  }
  attributes <- c(key, attributes)
  if (is.null(dq$dimension)) {
    dq$dimension <- list(name = attributes)
    names(dq$dimension) <- name
  } else {
    dim_names <- names(dq$dimension)
    dq$dimension <- c(dq$dimension, list(name = attributes))
    names(dq$dimension) <- c(dim_names, name)
  }
  dq
}