Returns the mean vector of the turning angles, as defined by Batschelet, (1981). A unit vector is created for each turning angle in the trajectory, and the centre-of-mass/mean vector is returned.
TrajMeanVectorOfTurningAngles(trj, compass.direction = NULL)Trajectory object.
If not NULL, step angles are calculated
relative to this angle (in radians), otherwise they are calculated relative
to the previous step angle.
A complex number r which represents the mean vector,
Mod(r) is the length of the mean vector which varies between 0 and
1, Arg(r) is the angle.
According to Batschelet (1981), r may serve as a straightness index
ranging from 0 to 1, where r is the length of the mean vector of
turning angles of a trajectory with constant step length. Values of r
near 1 indicating straighter paths. Hence, r =
Mod(TrajMeanVectorOfTurningAngles(trj)), assuming that trj has a
constant step length.