move: Move

Description

Wrapper for selecting different animal movement methods.

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

Usage

move(hypothesis = "crw", ...)
crw(agent, extent, stepLength, stddev, lonlat, torus = FALSE)
## S3 method for class 'SpatialPointsDataFrame':
crw(agent, extent, stepLength, stddev,
  lonlat, torus = FALSE)
## S3 method for class 'SpatialPoints':
crw(agent, extent, stepLength, stddev, lonlat,
  torus = FALSE)

Arguments

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

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.

Value

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

Details

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.

References

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