Computes and draws principal component.

## Usage

```
ternary_pca(x, y, z, ...)
# S4 method for numeric,numeric,numeric
ternary_pca(x, y, z, axis = 1, ...)
# S4 method for ANY,missing,missing
ternary_pca(x, axis = 1, ...)
```

## Arguments

- x, y, z
A

`numeric`

vector giving the x, y and z ternary coordinates of a set of points. If`y`

and`z`

are missing, an attempt is made to interpret`x`

in a suitable way (see`grDevices::xyz.coords()`

).- ...
Further arguments to be passed to

`graphics::lines()`

.- axis
An

`integer`

specifying the dimension to be plotted.

## See also

Other statistics:
`ternary_contour()`

,
`ternary_density()`

,
`ternary_ellipse()`

,
`ternary_hull()`

,
`ternary_mean()`

## Examples

```
## PCA
## Data from Aitchison 1986
ternary_plot(lava, panel.first = ternary_grid())
ternary_pca(lava, axis = 1, col = "red", lty = 2)
```