Contour plot of the skew skewnormal distribution in S^2

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Description

Contour plot of the skew skewnormal distribution in S^2.

Usage

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skewnorm.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)?

Details

The alr or the ilr transformation is applied to the compositional data at first. Then for a grid of points within the 2-dimensional simplex the bivariate skew skewnormal density is calculated and the contours are plotted along with the points.

Value

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

Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <mtsagris@yahoo.gr> and Giorgos Athineou <athineou@csd.uoc.gr>

References

Azzalini A. and Valle A. D. (1996). The multivariate skew-skewnormal distribution. Biometrika 83(4):715-726.

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

See Also

diri.contour, mixnorm.contour, bivt.contour, norm.contour

Examples

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x <- iris[51:100, 1:3]
x <- x / rowSums(x)
skewnorm.contour(x)
skewnorm.contour(x, type = "ilr")

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