Compositional (version 1.4)

Contour plot of the t distribution in S^2: Contour plot of the t distribution in $S^2$

Description

Contour plot of the t distribution in $S^2$.

Usage

bivt.contour(x, type = "alr", n = 100, appear = TRUE)

Arguments

x

A matrix with the compositional data. It has to be a 3 column matrix.

type

This is either "alr" or "ilr", corresponding to the additive and the isometric log-ratio transformation respectively.

n

The number of grid points to consider over which the density is calculated.

appear

Should the available data appear on the ternary plot (TRUE) or not (FALSE)?

Value

A ternary diagram with the points (if appear = TRUE) and the bivariate t contour lines.

Details

The alr or the ilr transformation is applied to the compositional data at first and the location, scatter and degrees of freedom of the bivariate t distribution are computed. Then for a grid of points within the 2-dimensional simplex the bivariate t density is calculated and the contours are plotted along with the points.

References

Aitchison J. (1986). The statistical analysis of compositional data. Chapman & Hall.

See Also

diri.contour, mixnorm.contour, norm.contour, skewnorm.contour

Examples

x <- iris[, 1:3]
x <- x / rowSums(x)
bivt.contour(x)
bivt.contour(x, type = "ilr")