Calculates the crown radius of a plant, given the x,y,z coordinates of the
leaves. See Details. Typically not invoked by user, but used by
summary.plant3d to estimate crown width.
Usage
getR(xyz)
Arguments
xyz
A matrix or dataframe of xyz coordinates.
Value
Returns only the mean crown radius of the four quadrants.
Details
The crown radius is the distance from the centre of the plant to the furthest
leaf in that direction. This distance is found for four directions
(corresponding to the four quadrants). The centre of the plant is found from
the average x,y coordinate (and may thus differ from the 'stem' location).