# FAQ

Here are answers to some common questions about ade4 (more to come soon).

## Installation

### How to install the current version of `ade4`?

The easiest way to install ade4 is to use `install.packages("ade4")` in your R session.

### How to install the development version of `ade4`?

To install the development version from github:

    remotes::install_github("adeverse/ade4")

### How do I know which `ade4` version I’m using?

In your R session, type:

    packageDescription("ade4", field="Version")

## Graphics

### What is `adegraphics`?

The package `adegraphics` provides a complete reimplementation of graphical functionalities of `ade4`. It is based on `lattice` and provides a convenient way to manage graphics as objects. Moreover, it offers much more flexibility than `ade4` to customize your plots.

### How to load `adegraphics`?

As `adegraphics` provides a reimplementation of `ade4` graphical functions, many functions have the same name in the two packages. To be sure to use `adegraphics` functions, `adegraphics` should be loaded after `ade4`:

    library(ade4)
    library(adegraphics)

An alternative it to explicitly specify the package in the call using the `::` operator:

    adegraphics::s.label()

### How to interpret ellipses plotted by `s.class` function?

The ellipses represent the main variation for individuals of a given class. They are based on inertia statistics not on significance levels.

## Simple Analysis

### How to obtain coordinates for individuals?

In simple analysis (e.g., `dudi.pca`), scores for individuals are stored in `$li` element of the returned object

### How to obtain coordinates for variables?

In simple analysis (e.g., `dudi.pca`), scores for variables are stored in `$co` element of the returned object

### What are the `$l1` and `$c1` elements of a dudi ?

In simple analysis (e.g., `dudi.pca`), the `$c1` element contains the principal axes (aka “loadings” of the variables) and the `$l1` element contains the principal components. The norm of these two elements is equal to 1, which makes them useful for drawing biplots (for example).