Adjust edges of graph to walk on

This function adjusts a previously created list of nodes and edges to include new nodes and edges and/or reevaluate the appropriateness of the old ones. The output is then used in the find_path to find the shortest path from the agent to the goal.

Usage

adjust_edges(
  from,
  to,
  background,
  precomputed_edges,
  space_between = 0.5,
  new_objects = NULL,
  reevaluate = !is.null(new_objects),
  cpp = TRUE
)

Arguments

from

Numeric denoting the coordinate from which to begin routes.

to

Numeric denoting the coordinate from which to end routes.

background

Object of the background-class.

precomputed_edges

Previously computed edges, usually the output of compute_edges.

space_between

Numeric denoting the space to leave between the circumference of the object and the nodes created under the hood (see add_nodes). Defaults to 0.5.

new_objects

List of instances of the object-class that were previously not contained in the objects slot of the background when computing the edges provided in precomputed_edges. Typically, these are other pedestrians that an agent wants to account for when rerouting. Defaults to NULL, so that only from and to are added to the already existing edges.

reevaluate

Logical denoting whether to reevaluate the appropriateness of the edges that are contained in the precomputed_edges. Defaults to TRUE when new_objects is not empty, and to FALSE whenever it is.

cpp

Logical denoting whether to use the R or Rcpp version of the function. Defaults to TRUE.

Value

List containing a dataframe with the surviving nodes under "nodes", a dataframe with the surviving connections between nodes under "edges", and a similar dataframe to the previous one but with the coordinates still in there under "edges_with_coords".

Details

Goes through a similar type of steps as create_edges, with the exception that adjust_edges takes in already computed and evaluated edges and adjusts those for the current purposes of the environment, there where create_edges creates these same edges from scratch.

See also

background-class, add_nodes, find_path, limit_access, combine_nodes, compute_edges, create_edges, create_nodes, evaluate_edges

Examples

# Define a background in which the agent can move
my_background <- background(shape = rectangle(center = c(0, 0), 
                                              size = c(2, 2)), 
                            objects = list(rectangle(center = c(0, 0), 
                                                     size = c(1, 1))))

# Create precomputed edges
edges <- compute_edges(my_background, 
                       space_between = 0.25,
                       many_nodes = FALSE)
head(edges$edges)
#>       from     to       cost
#> 2.2 node 1 node 2 1.83210678
#> 2.4 node 1 node 4 1.83210678
#> 2.5 node 1 node 5 0.04289322
#> 2.6 node 1 node 6 2.27144661
#> 2.8 node 1 node 8 2.27144661
#> 3.1 node 2 node 1 1.83210678

# Adjust these edges and provide values for the from and to arguments
adjusted_edges <- adjust_edges(c(-0.75, 0), 
                               c(0.75, 0), 
                               my_background, 
                               edges,
                               space_between = 0.25)
head(adjusted_edges$edges)
#>       from    to      cost
#> 2   node 1 agent 0.4633883
#> 3   node 2 agent 0.4633883
#> 4.1 node 3  goal 0.4633883
#> 5.1 node 4  goal 0.4633883
#> 6   node 5 agent 0.6830583
#> 7   node 6 agent 0.6830583