R/layout_nodes_w_string.R

In DiagrammeR: Graph/Network Visualization

#' Layout nodes using a text-based schematic
#'
#' @description
#'
#' Layout one or several groups of nodes using a text-based schematic. The
#' option is available to apply sorting to each of the groups.
#'
#' @inheritParams render_graph
#' @param layout A layout character string that provides a schematic for the
#'   layout. This consists of a rectangular collection of `-` characters (for no
#'   node placement), and numbers from `1` to `9` (representing different
#'   groupings of nodes, further described in the `nodes` argument).
#' @param nodes A named vector of the form: `c("1" = "[node_attr]:[value]",
#'   ...)`. The LHS corresponds to the numbers used in the `layout` schematic.
#'   The RHS provides a shorthand for the node attribute and a value for
#'   grouping together nodes (separated by a colon). For instance, with
#'   `"type:a"` in the RHS (and `"1"` in the LHS) we would target all nodes with
#'   a `type` attribute equal to `a` for positioning in the graph as described
#'   by the `1`s in the `layout`.
#' @param sort An optional sorting method to apply to the collection of nodes
#'   before assigning positional information. Like `nodes`, this is a named
#'   vector of the form: `c("1" = "[node_attr]:asc|desc", ...)`. The `node_attr`
#'   in this case should be different than that used in `nodes`. Ideally, this
#'   node attribute should have unique values. Choose either `asc` or `desc`
#'   right of the colon for ascending or descending sorts.
#' @param width The width of the `layout` diagram.
#' @param height The height of the `layout` diagram.
#' @param ll A vector describing the the lower-left coordinates of the `layout`
#'
#' @return A graph object of class `dgr_graph`.
#'
#' @examples
#' # Create a graph with unique labels and
#' # several node `type` groupings
#' graph <-
#'   create_graph() %>%
#'   add_node(type = "a", label = "a") %>%
#'   add_node(type = "a", label = "b") %>%
#'   add_node(type = "b", label = "c") %>%
#'   add_node(type = "b", label = "d") %>%
#'   add_node(type = "b", label = "e") %>%
#'   add_node(type = "c", label = "f") %>%
#'   add_node(type = "c", label = "g")
#'
#' # Define a 'layout' for groups of nodes
#' # using a text string (dashes are empty
#' # grid cells, numbers--representing
#' # ad-hoc groupings--correspond to
#' # individual nodes); here, define a layout
#' # with 3 groups of nodes
#' layout <-
#' "
#' 1--------
#' 1--------
#' ---222---
#' --------3
#' --------3
#' "
#'
#' # Use the `layout` along with what nodes
#' # the numbers correspond to in the graph
#' # with the `nodes` named vectors; the
#' # optional `sort` vector describes how
#' # we should sort the collection of node
#' # before adding position information
#' graph <-
#'   graph %>%
#'   layout_nodes_w_string(
#'     layout = layout,
#'     nodes = c("1" = "type:a",
#'               "2" = "type:b",
#'               "3" = "type:c"),
#'     sort = c("1" = "label:asc",
#'              "2" = "label:desc",
#'              "3" = "label:desc"))
#'
#' # Show the graph's node data frame
#' # to confirm that `x` and `y` values
#' # were added to each of the nodes
#' graph %>% get_node_df()
#' @family Node creation and removal
#' @export
layout_nodes_w_string <- function(
    graph,
    layout,
    nodes,
    sort = NULL,
    width = 8,
    height = 8,
    ll = c(0, 0)
) {

  # Get the time of function start
  time_function_start <- Sys.time()

  # Get the name of the function
  fcn_name <- get_calling_fcn()

  # Validation: Graph object is valid
  if (graph_object_valid(graph) == FALSE) {

    emit_error(
      fcn_name = fcn_name,
      reasons = "The graph object is not valid")
  }

  # Get the graph's internal node data frame
  # (ndf) into a separate object
  ndf <- graph$nodes_df

  # Get the total number of groups described
  # in the layout
  node_group_count <- length(nodes)

  # Parse the `layout` object to get a vector
  # of rows
  layout <-
    gsub(" ", "", layout) %>%
    stringr::str_split("\n") %>%
    unlist()

  layout <-
    layout[which(layout != "")]

  # Determine the row length from the layout text
  layout_row_length <- vector(mode = "numeric")

  for (i in 1:length(layout)) {
    layout_row_length <-
      c(layout_row_length, nchar(layout[i]))
  }

  # Stop function if not all rows are of equal length
  if (mean(layout_row_length) != layout_row_length[1]) {

    emit_error(
      fcn_name = fcn_name,
      reasons = "Each row must have the same length")
  }

  layout_column_number <- layout_row_length <- layout_row_length[1]
  layout_row_number <- layout_column_length <- length(layout)

  # Define the exact `x` and `y` positions in which
  # the nodes could be placed
  x_pts <- seq(0, width, width/(layout_column_number - 1)) + ll[1]
  y_pts <- rev(seq(0, height, height/(layout_row_number - 1))) + ll[2]

  # Create a tibble called `ndf_parts`
  ndf_parts <- dplyr::tibble()

  for (k in 1:node_group_count) {

    # Create empty table with position and node ID
    position_table <- dplyr::tibble(x = numeric(0), y = numeric(0))

    node_group <- names(nodes)[k]
    node_select <- nodes[[k]]

    node_attr <- unlist(stringr::str_split(node_select, ":"))[1]
    node_attr_val <- unlist(stringr::str_split(node_select, ":"))[2]

    sort_attr <- unlist(stringr::str_split(sort[k], ":"))[1]
    sort_dir <- unlist(stringr::str_split(sort[k], ":"))[2]

    for (i in 1:layout_row_number) {
      for (j in 1:layout_column_number) {

        if (unlist(stringr::str_split(layout[i], ""))[j] == k) {

          item_table <-
            dplyr::tibble(
              x = x_pts[j],
              y = y_pts[i])

          position_table <-
            position_table %>%
            dplyr::bind_rows(item_table)
        }
      }
    }

    # Filter the graph `ndf`
    ndf_part <-
      ndf %>%
      dplyr::filter(!! rlang::parse_expr(paste0(node_attr, " == '", node_attr_val, "'")))

    # Optionally apply sorting
    if (!is.null(sort)) {
      if (sort_dir == "desc") {
        ndf_part <-
          ndf_part %>%
          dplyr::arrange(dplyr::desc(!! sym(sort_attr)))

      } else {
        ndf_part <-
          ndf_part %>%
          dplyr::arrange(!! sym(sort_attr))
      }
    }

    # Trim rows from the position table if its
    # row count is greater than that of `ndf_part`
    if (nrow(position_table) > nrow(ndf_part)) {
      position_table <- position_table[1:nrow(ndf_part), ]
    }

    # Bind `position_table` to the split `ndf_part`
    ndf_part <-
      dplyr::bind_cols(position_table, ndf_part)

    # Bind `ndf_part` to `ndf_parts`
    ndf_parts <-
      dplyr::bind_rows(ndf_parts, ndf_part)
  }

  # Join the `ndf_parts` to the main `ndf`
  ndf <-
    ndf %>%
    dplyr::left_join(
      ndf_parts,
      by = c("id", "type", "label"))

  # Replace the graph's ndf with the revised version
  graph$nodes_df <- ndf

  # Update the `graph_log` df with an action
  graph$graph_log <-
    add_action_to_log(
      graph_log = graph$graph_log,
      version_id = nrow(graph$graph_log) + 1,
      function_used = fcn_name,
      time_modified = time_function_start,
      duration = graph_function_duration(time_function_start),
      nodes = nrow(graph$nodes_df),
      edges = nrow(graph$edges_df))

  # Write graph backup if the option is set
  if (graph$graph_info$write_backups) {
    save_graph_as_rds(graph = graph)
  }

  graph
}