eigenvals {vegan} R Documentation

## Extract Eigenvalues from an Ordination Object

### Description

Function extracts eigenvalues from an object that has them. Many multivariate methods return such objects.

### Usage

```eigenvals(x, ...)
## S3 method for class 'cca':
eigenvals(x, constrained = FALSE, ...)
## S3 method for class 'eigenvals':
summary(object, ...)
```

### Arguments

 `x` An object from which to extract eigenvalues. `object` An `eigenvals` result object. `constrained` Return only constrained eigenvalues. `...` Other arguments to the functions (usually ignored)

### Details

This is a generic function that has methods for `cca`, `wcmdscale`, `prcomp` and `princomp` result objects. The default method also extracts eigenvalues if the result looks like being from `eigen` or `svd`. Functions `prcomp` and `princomp` contain square roots of eigenvalues that all called standard deviations, but `eigenvals` function returns their squares. Function `svd` contains singular values, but function `eigenvals` returns their squares. For constrained ordination methods `cca`, `rda` and `capscale` the function returns the both constrained and unconstrained eigenvalues concatenated in one vector, but the partial component will be ignored. However, with argument `constrained = TRUE` only constrained eigenvalues are returned.

The `summary` of `eigenvals` result returns eigenvalues, proportion explained and cumulative proportion explained.

### Value

An object of class `"eigenvals"` which is a vector of eigenvalues.

### Author(s)

Jari Oksanen.

`eigen`, `svd`, `prcomp`, `princomp`, `cca`, `rda`, `capscale`, `wcmdscale`, `cca.object`.

### Examples

```data(varespec)
data(varechem)
mod <- cca(varespec ~ Al + P + K, varechem)
ev <- eigenvals(mod)
ev
summary(ev)
```

[Package vegan version 1.16-32 Index]