Don {wildlifeDI}

Doncaster's measure of dynamic interaction

Description

The function Don measures the dynamic interaction between two moving objects following the methods outlined by Doncaster (1990).

Usage

Don(traj, traj2, tc = 0, dc = 0, plot = TRUE)

Arguments

traj

an object of the class move2 which contains the time-stamped movement fixes of at least two individuals. For more information on objects of this type see help(mt_as_move2).

traj2

(optional) same as traj, but for the second group of individuals. See checkTO

tc

time threshold for determining simultaneous fixes – see function: GetSimultaneous.

dc

distance tolerance limit (in appropriate units) for defining when two fixes are spatially together.

plot

logical, whether or not to plot the Doncaster plot. Default = TRUE.

Details

This function can be used to compute the Doncaster (1990) methods for measuring dynamic interaction between two objects. The Doncaster method tests the proportion of simultaneous fixes that are below dc against that which would be expected based on the distribution of distances between all fixes.

Value

A data.frame is returned that contains the values for the contingency table of simultaneous fixes (paired) and non-paired fixes below and above dc, along with the associated p-value from the Chi-squared test.This function can optionally return a plot, for distance values ranging from 0 to the maximum distance separating two fixes, of the observed proportion of simultaneous fixes below each distance value (for each pair). The expected values based on all fixes are also included.

References

Doncaster, C.P. (1992) Non-parametric estimates of interaction from radio-tracking data. Journal of Theoretical Biology, 143: 431-443.

See Also

GetSimultaneous

Examples

data(deer)
#tc = 7.5 minutes, dc = 50 meters
Don(deer, tc = 7.5*60, dc = 50)