# bivt.contour: Contour plot of the t distribution in S^2 In Compositional: Compositional Data Analysis

 Contour plot of the t distribution in S^2 R Documentation

## 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, cont.line = FALSE)
```

### Arguments

 `x` A matrix with 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)? `cont.line` Do you want the contour lines to appear? If yes, set this TRUE.

### 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.

### Value

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

### References

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

```diri.contour, mix.compnorm.contour, compnorm.contour, skewnorm.contour ```

### Examples

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

Compositional documentation built on July 8, 2022, 1:06 a.m.