wildlifeDI (version 0.5.1)

Cr: Movement Correlation Coefficient

Description

The function Cr computes the correlation statistic for movement data as presented in the paper by Shirabe (2006). The statistic is essentially a Pearson product-moment correlation statistic formulated for use with movement data.

Usage

Cr(traj1, traj2, tc = 0)

Value

This function returns the Shirabe (2006) correlation statistic for two moving objects.

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.

Details

The function Cr can be used to measure the level of dynamic interaction (termed correlation) between a pair of simultaneously moving objects. The statistic is sensitive to interaction in both movement direction (azimuth) and displacement, but is unable to disentangle the effects of these components. NOTE: This function is only appropriate with projected coordinates.

References

Shirabe, T. 2006. Correlation analysis of discrete motions. In: Raubal, M., Miller, HJ, Frank, AU, and Goodchild, M. eds. GIScience 2006, LNCS 4197. Berlin: Springer-Verlag; 370-382.

See Also

GetSimultaneous, DI

Examples

data(deer)
deer37 <- deer[1]
deer38 <- deer[2]
#tc = 7.5 minutes
Cr(deer37, deer38, tc = 7.5*60)