Compute cell centers

Compute cell centers based on a person's current position and velocity, accounting for potential changes in speed and direction. Alternative to c_vd that accounts for biomechanical limitations in the speed one can maintain when turning at a greater angle. Defaults are based on Seethapathi et al. (2024), Brown et al. (2020), and Glaister et al. (2007).

Usage

compute_centers(
  agent,
  velocities = matrix(rep(c(1.5, 1, 0.5), each = 11), ncol = 3),
  orientations = matrix(rep(c(72.5, 50, 32.5, 20, 10, 0, 350, 340, 327.5, 310, 287.5),
    times = 3), ncol = 3),
  time_step = 0.5,
  cpp = TRUE
)

Arguments

agent

Object of the agent-class.

velocities

Numeric matrix containing the change in speed for an agent whenever they move to the respective cell of this matrix. Defaults to a matrix in which the columns contain 1.5 (acceleration), 1, and 0.5.

orientations

Numeric matrix containing the change in direction for an agent whenever they move to the respective cell of this matrix. Defaults to a matrix in which the rows contain 72.5, 50, 32.5, 20, 10, 0, 350, 340, 327.5, 310, 287.5 (note that the larger angles are actually the negative symmetric versions of the smaller angles).

time_step

Numeric denoting the number of seconds each discrete step in time should mimic. Defaults to 0.5, or half a second.

cpp

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

Value

Numeric matrix of (x, y) coordinates for each cell

See also

agent-class, c_vd moving_options

Examples

# Create two agents, one fast and one slow
slow_agent <- agent(center = c(-2.75, 0),
                    radius = 0.25,
                    speed = 0.5,
                    orientation = 0,
                    current_goal = goal(position = c(-2.01, 0)))

fast_agent <- agent(center = c(-2.75, 0),
                    radius = 0.25,
                    speed = 2,
                    orientation = 0,
                    current_goal = goal(position = c(-2.01, 0)))

# Generate the cell centers with predped
slow_centers <- compute_centers(slow_agent)
fast_centers <- compute_centers(fast_agent)

# Generate the cell centers with m4ma
slow_m4ma <- m4ma::c_vd(1:33,
                        position(slow_agent),
                        speed(slow_agent),
                        orientation(slow_agent))
fast_m4ma <- m4ma::c_vd(1:33,
                        position(fast_agent),
                        speed(fast_agent),
                        orientation(fast_agent))

# Compare both through a plot. This should show that the predped variant
# accounts for an interaction between an agent's speed and change in
# direction when computing the cell centers
base::plot(slow_centers, col = "black")
graphics::points(slow_m4ma[, 1], slow_m4ma[, 2], col = "red")


base::plot(fast_centers, col = "black")
graphics::points(fast_m4ma[, 1], fast_m4ma[, 2], col = "red")