# Don: Doncaster's measure of dynamic interaction In wildlifeDI: Calculate Indices of Dynamic Interaction for Wildlife Tracking Data

## Description

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

## Usage

 `1` ```Don(traj1, traj2, tc = 0, dc = 50, plot = TRUE) ```

## Arguments

 `traj1` an object of the class `ltraj` which contains the time-stamped movement fixes of the first object. Note this object must be a ```type II ltraj``` object. For more information on objects of this type see ``` help(ltraj)```. `traj2` same as `traj1`. `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

This function first returns 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. The expected values based on all fixes are also included. Second, a list is returned that contains 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.

• conTable – contingency table showing frequency of paired and non-paired fixes above and below `dc`.

• p.value – p-value from the Chi-squared test of `conTable`.

## References

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

 ```1 2 3 4 5``` ```data(deer) deer37 <- deer[1] deer38 <- deer[2] #tc = 7.5 minutes, dc = 50 meters Don(deer37, deer38, tc = 7.5*60, dc = 50) ```