Add Nodes along the Outside or Inside of an Object

Used in the create_nodes function for creating path- points the agents can use to walk around objects. Currently works for all instances of object-class, but only returns NULL for the segment-class.

Usage

add_nodes(object, ...)

# S4 method for class 'polygon'
add_nodes(
  object,
  space_between = 0.5,
  only_corners = FALSE,
  outside = TRUE,
  cpp = TRUE
)

# S4 method for class 'circle'
add_nodes(
  object,
  space_between = 0.5,
  only_corners = FALSE,
  outside = TRUE,
  cpp = TRUE
)

# S4 method for class 'segment'
add_nodes(object, ...)

Arguments

object

Object of object-class.

...

Arguments passed on to the methods of this generic

space_between

Numeric denoting the space to leave between the circumference of the object and the nodes to create. When outside = TRUE, space_between distance is created to the outside of the object, while if outside = FALSE this same distance is created towards the inside of the object. Defaults to 0.5.

only_corners

Logical denoting whether to only add nodes at the corners of each object (TRUE) or to also add nodes between these newly created corner-nodes (FALSE). When only_corners = FALSE, other nodes that are added have a distance of space_between between them. Defaults to FALSE.

outside

Logical denoting whether the nodes should lie on the outside (TRUE) or inside (FALSE) of the object. Defaults to TRUE.

cpp

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

Value

Numerical matrix containing the nodes that were created around/within the provided object.

Details

This method is related to the nodes_on_circumference, but differs in the respect that nodes_on_circumference adds nodes directly on the circumference of an object, while add_nodes adds nodes on the outside of inside of an object.

Please note that if only_corners = TRUE for the circle-class, that the nodes are chosen in such a way that they are at a distance of space_between away from the circumference of the circle AND so that this node is connected to its neighbours through a tangential line to the circle. In agent-based terms, this means that if an agent stands at one of the nodes that are created, they can also see alternative nodes around the circle. If only_corners = FALSE, the general logic is used to determine where the other nodes should end up.

See also

circle-class, polygon-class, rectangle-class, segment-class, nodes_on_circumference, create_nodes

Examples

# Create an object
my_circle <- circle(center = c(0, 0), radius = 1)

# Generate nodes that fall around this circle with a distance of 1 around 
# the circle
add_nodes(my_circle, space_between = 1)
#>                [,1]          [,2]
#>  [1,]  2.000000e+00  0.000000e+00
#>  [2,]  1.847759e+00  7.653669e-01
#>  [3,]  1.414214e+00  1.414214e+00
#>  [4,]  7.653669e-01  1.847759e+00
#>  [5,]  1.224647e-16  2.000000e+00
#>  [6,] -7.653669e-01  1.847759e+00
#>  [7,] -1.414214e+00  1.414214e+00
#>  [8,] -1.847759e+00  7.653669e-01
#>  [9,] -2.000000e+00  2.449294e-16
#> [10,] -1.847759e+00 -7.653669e-01
#> [11,] -1.414214e+00 -1.414214e+00
#> [12,] -7.653669e-01 -1.847759e+00
#> [13,] -3.673940e-16 -2.000000e+00
#> [14,]  7.653669e-01 -1.847759e+00
#> [15,]  1.414214e+00 -1.414214e+00
#> [16,]  1.847759e+00 -7.653669e-01
#> [17,]  2.000000e+00 -4.898587e-16

# Note that for segments, this function returns NULL
my_segment <- segment(from = c(0, 0), to = c(2, 2))
add_nodes(my_segment)
#> NULL