Wrapper for selecting different animal movement methods.

This version uses just turn angles and step lengths to define the correlated random walk.

`move(hypothesis = "crw", ...)`crw(agent, extent, stepLength, stddev, lonlat, torus = FALSE)

# S4 method for SpatialPointsDataFrame
crw(agent, extent, stepLength, stddev,
lonlat, torus = FALSE)

# S4 method for SpatialPoints
crw(agent, extent, stepLength, stddev, lonlat,
torus = FALSE)

hypothesis

Character vector, length one, indicating which movement
hypothesis/method to test/use. Currently defaults to
'crw' (correlated random walk) using `crw`

.

...

arguments passed to the function in `hypothesis`

agent

A `SpatialPoints*`

object.
If a `SpatialPointsDataFrame`

, 2 of the columns must
be `x1`

and `y1`

, indicating the previous location.
If a `SpatialPoints`

object, then `x1`

and
`y1`

will be assigned randomly.

extent

An optional `Extent`

object that will be used for `torus`

.

stepLength

Numeric vector of length 1 or number of agents describing step length.

stddev

Numeric vector of length 1 or number of agents describing standard deviation of wrapped normal turn angles.

lonlat

Logical. If `TRUE`

, coordinates should be in degrees.
If `FALSE`

coordinates represent planar ('Euclidean')
space (e.g. units of meters)

torus

Logical. Should the crw movement be wrapped to the opposite
side of the map, as determined by the `extent`

argument.
Default `FALSE`

.

A SpatialPointsDataFrame object with updated spatial position defined by a single occurence of step length(s) and turn angle(s).

This simple version of a correlated random walk is largely the version that was presented in Turchin 1998, but it was also used with bias modifications in McIntire, Schultz, Crone 2007.

Turchin, P. 1998. Quantitative analysis of movement: measuring and modeling population redistribution in animals and plants. Sinauer Associates, Sunderland, MA.

McIntire, E. J. B., C. B. Schultz, and E. E. Crone. 2007. Designing a network for butterfly habitat restoration: where individuals, populations and landscapes interact. Journal of Applied Ecology 44:725-736.