# skewnorm.contour: Contour plot of the skew skewnormal distribution in S^2 In Compositional: Compositional Data Analysis

## Description

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

## Usage

 `1` ```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 <[email protected]> and Giorgos Athineou <[email protected]>

## 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.

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

## Examples

 ```1 2 3 4``` ```x <- as.matrix(iris[51:100, 1:3]) x <- x / rowSums(x) skewnorm.contour(x) skewnorm.contour(x, type = "ilr") ```

### Example output

```
```

Compositional documentation built on Jan. 14, 2018, 5:03 p.m.