| Rbar2kappa {geostats} | R Documentation |
\bar{R} to \kappa conversion
Description
Converts the empirical concentration parameter
\bar{R} to the von-Mises concentration parameter
\kappa.
Usage
Rbar2kappa(R, p = 1)
Arguments
R |
a scalar or vector of values between 0 and 1 |
p |
the number of parameters |
Details
\bar{R} and \kappa are two types of
concentration parameter that are commonly used in directional
data analysis. \kappa is one of the parameters of the
parametric von Mises distribution, which is difficult to
estimate from the data. \bar{R} is easier to calculate
from data. Rbar2kappa converts \bar{R} to
\bar{\kappa} using the following approximate empirical
formula:
\kappa =
\frac{\bar{R}(p+1-\bar{R}^2)}{1-\bar{R}^2}
where p marks the number of parameters in the data space (1
for circle, 2 for a sphere).
Value
value(s) between 0 and +\infty
References
Banerjee, A., et al. “Clustering on the unit hypersphere using von Mises-Fisher distributions.” Journal of Machine Learning Research 6.Sep (2005): 1345-1382.
Examples
data(striations,package='geostats')
Rbar2kappa(Rbar(striations,degrees=TRUE))