Move the turtles backward of their headings' directions.

bk(turtles, dist, world, torus = FALSE, out = TRUE)

# S4 method for agentMatrix,numeric
bk(turtles, dist, world, torus = FALSE,
  out = TRUE)

Arguments

turtles

AgentMatrix object representing the moving agents.

dist

Numeric. Vector of distances to move. Must be of length 1 or of length turtles.

world

WorldMatrix or worldArray object.

torus

Logical to determine if the world is wrapped. Default is torus = FALSE.

out

Logical. Determine if a turtle should move when torus = FALSE and its ending position will be outside of the world's extent. Default is out = TRUE.

Value

AgentMatrix representing the turtles with updated coordinates and updated data for their previous coordinates "prevX" and "prevY".

Details

If torus = FALSE and out = TRUE, world does not need to be provided.

If a distance to move leads a turtle outside of the world's extent and torus = TRUE, the turtle is relocated on the other side of the world, inside its extent; if torus = FALSE and out = TRUE, the turtle moves past the world's extent; if torus = FALSE and out = FALSE, the turtle does not move at all. In the event that a turtle does not move, its previous coordinates are still updated with its position before running bk() (i.e., its current position).

If a given dist value is negative, then the turtle moves forward.

The turtles' headings are not affected by the function (i.e., the turtles do not face backward).

References

Wilensky, U. 1999. NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University. Evanston, IL.

See also

Examples

w1 <- createWorld(minPxcor = 0, maxPxcor = 4, minPycor = 0, maxPycor = 4, data = runif(25)) t1 <- createOTurtles(n = 10, world = w1) plot(w1)
points(t1, col = of(agents = t1, var = "color"), pch = 16)
t1 <- fd(turtles = t1, dist = 2) points(t1, col = of(agents = t1, var = "color"), pch = 16)
t1 <- bk(turtles = t1, dist = 1) points(t1, col = of(agents = t1, var = "color"), pch = 16)
t1 <- fd(turtles = t1, dist = 0.5) points(t1, col = of(agents = t1, var = "color"), pch = 16)