R/tibble.R

In sfnetworks: Tidy Geospatial Networks

#' Extract the active element of a sfnetwork as spatial tibble
#'
#' The sfnetwork method for \code{\link[tibble]{as_tibble}} is conceptually
#' different. Whenever a geometry list column is present, it will by default
#' return what we call a 'spatial tibble'. With that we mean an object of
#' class \code{c('sf', 'tbl_df')} instead of an object of class
#' \code{'tbl_df'}. This little conceptual trick is essential for how
#' tidyverse functions handle \code{\link{sfnetwork}} objects, i.e. always
#' using the corresponding \code{\link[sf]{sf}} method if present. When using
#' \code{\link[tibble]{as_tibble}} on \code{\link{sfnetwork}} objects directly
#' as a user, you can disable this behaviour by setting \code{spatial = FALSE}.
#'
#' @param x An object of class \code{\link{sfnetwork}}.
#'
#' @param active Which network element (i.e. nodes or edges) to activate before
#' extracting. If \code{NULL}, it will be set to the current active element of
#' the given network. Defaults to \code{NULL}.
#'
#' @param spatial Should the extracted tibble be a 'spatial tibble', i.e. an
#' object of class \code{c('sf', 'tbl_df')}, if it contains a geometry list
#' column. Defaults to \code{TRUE}.
#'
#' @param ... Arguments passed on to \code{\link[tibble]{as_tibble}}.
#'
#' @return The active element of the network as an object of class
#' \code{\link[tibble]{tibble}}.
#'
#' @name as_tibble
#'
#' @examples
#' library(tibble, quietly = TRUE)
#'
#' net = as_sfnetwork(roxel)
#'
#' # Extract the active network element as a spatial tibble.
#' as_tibble(net)
#'
#' # Extract any network element as a spatial tibble.
#' as_tibble(net, "edges")
#'
#' # Extract the active network element as a regular tibble.
#' as_tibble(net, spatial = FALSE)
#'
#' @importFrom tibble as_tibble
#' @importFrom tidygraph as_tbl_graph
#' @export
as_tibble.sfnetwork = function(x, active = NULL, spatial = TRUE, ...) {
  if (is.null(active)) {
    active = attr(x, "active")
  }
  if (spatial) {
    switch(
      active,
      nodes = nodes_as_sf(x),
      edges = edges_as_table(x),
      raise_unknown_input(active)
    )
  } else {
    switch(
      active,
      nodes = as_tibble(as_tbl_graph(x), "nodes"),
      edges = as_tibble(as_tbl_graph(x), "edges"),
      raise_unknown_input(active)
    )
  }
}

#' @importFrom tibble as_tibble
#' @importFrom tidygraph as_tbl_graph
edges_as_table = function(x) {
  if (has_explicit_edges(x)) {
    edges_as_sf(x)
  } else {
    as_tibble(as_tbl_graph(x), "edges")
  }
}