Evaluate whether edges pass through objects

This function evaluates whether the connections that are made between nodes are reachable, that is that the paths are not blocked by any objects. This also accounts for the one-way blockages that are present in the limited_access slot of the background-class.

Usage

evaluate_edges(segments, background, space_between, cpp = TRUE)

Arguments

segments

Named matrix or dataframe containing the ids of the nodes under column names "from" and "to", and their coordinates under "from_x", "from_y", "to_x", and "to_y".

background

Object of the background-class.

space_between

Numeric denoting the space that should be left between an object and the created path points for the agents.

cpp

Logical denoting whether to use the Rcpp alternative (TRUE) or the R alternative of this function (FALSE). Defaults to TRUE.

Value

List containing a dataframe with the surviving connections between the nodes under "edges" and a similar dataframe also containing the coordinates under "edges_with_coords".

Details

In this function, a lot of the heavy lifting is done by the line_intersection method and the prune_edges function.

See also

adjust_edges, create_edges, prune_edges, line_intersection

Examples

# Let's create a background
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 some segments that do and do not go through the objects in the 
# background
potential_edges <- data.frame(from = c("node 1", "node 2", "node 3"), 
                              from_x = c(-0.75, -0.75, -0.75), 
                              from_y = c(0, 0, 0),
                              to = c("node 4", "node 5", "node 6"),
                              to_x = c(-0.75, 0.75, 0.95), 
                              to_y = c(0.75, 0, 0.95))
head(potential_edges)
#>     from from_x from_y     to  to_x to_y
#> 1 node 1  -0.75      0 node 4 -0.75 0.75
#> 2 node 2  -0.75      0 node 5  0.75 0.00
#> 3 node 3  -0.75      0 node 6  0.95 0.95

# Only retain the edges that don't intersect the object
surviving_edges <- evaluate_edges(potential_edges, 
                                  my_background,
                                  space_between = 0)
head(surviving_edges$edges_with_coords)
#>     from from_x from_y     to  to_x to_y   cost
#> 1 node 1  -0.75      0 node 4 -0.75 0.75 0.5625