spher.esag.contour: Contour plot (on the sphere) of the ESAG and Kent...
In Directional: A Collection of Functions for Directional Data Analysis

Contour plot (on the sphere) of the ESAG and Kent distributions

R Documentation

Contour plot (on the sphere) of the ESAG and Kent distributions

Description

The contour plot (on the sphere) of the ESAG and Kent distributions is produced.

Usage

spher.esag.contour(mu, gam, bgcol = "snow", dat = NULL, col = NULL,
lat = 50, long = 50)
spher.kent.contour(G, param, bgcol = "snow", dat = NULL, col = NULL,
lat = 50, long = 50)

Arguments

`mu`	The mean vector the ESAG distribution, a vector in `R^3`.
`gam`	The two gamma parameters of the ESAG distribution.
`G`	For the Kent distribution, a 3 x 3 matrix whose first column is the mean direction. The second and third columns are the major and minor axes respectively.
`param`	For the Kent distribution a vector with the concentration `\kappa` and ovalness `\beta` parameters. The angle `\psi` has been absorbed inside the matrix G.
`bgcol`	The color of the surface of the sphere.
`dat`	If you have you want to plot supply them here. This has to be a numerical matrix with three columns, i.e. unit vectors.
`col`	If you supplied data then choose the color of the points. If you did not choose a color, the points will appear in red.
`lat`	A positive number determing the range of degrees to move left and right from the latitude center. See the example to better understand this argument.
`long`	A positive number determing the range of degrees to move up and down from the longitude center. See the example to better understand this argument.

Details

The goal of this function is for the user to see how the ESAG or the Kent distribution looks like.

Value

A plot containing the contours of the distribution.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris mtsagris@uoc.gr.

References

Kent John (1982). The Fisher-Bingham distribution on the sphere. Journal of the Royal Statistical Society, Series B, 44(1): 71–80.

Paine P.J., Preston S.P., Tsagris M. and Wood A.T.A. (2018). An Elliptically Symmetric Angular Gaussian Distribution. Statistics and Computing, 28(3):689–697.

Examples


mu <- colMeans( as.matrix( iris[, 1:3] ) )
gam <- c(1 ,0.5)
## the lat and long are decreased to 30. Increase them back to 50 to
## see the difference
spher.esag.contour(mu, gam, lat = 30, long = 30)

Directional documentation built on Oct. 30, 2024, 9:15 a.m.