# dudi: Duality Diagram In ade4: Analysis of Ecological Data: Exploratory and Euclidean Methods in Environmental Sciences

 dudi R Documentation

## Duality Diagram

### Description

`as.dudi` is called by many functions (`dudi.pca`, `dudi.coa`, `dudi.acm`, ...) and not directly by the user. It creates duality diagrams.

`t.dudi` returns an object of class '`dudi`' where the rows are the columns and the columns are the rows of the initial `dudi`.

`is.dudi` returns TRUE if the object is of class `dudi`

`redo.dudi` computes again an analysis, eventually changing the number of kept axes. Used by other functions.

### Usage

```as.dudi(df, col.w, row.w, scannf, nf, call, type, tol = 1e-07,
full = FALSE)
## S3 method for class 'dudi'
print(x, ...)
is.dudi(x)
redo.dudi(dudi, newnf = 2)
## S3 method for class 'dudi'
t(x)
## S3 method for class 'dudi'
summary(object, ...)
## S3 method for class 'dudi'
x[i,j]
```

### Arguments

 `df` a data frame with n rows and p columns `col.w` a numeric vector containing the row weights `row.w` a numeric vector containing the column weights `scannf` a logical value indicating whether the eigenvalues bar plot should be displayed `nf` if scannf FALSE, an integer indicating the number of kept axes `call` generally `match.call()` `type` a string of characters : the returned list will be of class `c(type, "dudi")` `tol` a tolerance threshold for null eigenvalues (a value less than tol times the first one is considered as null) `full` a logical value indicating whether all non null eigenvalues should be kept `x, dudi, object` objects of class `dudi` `...` further arguments passed to or from other methods `newnf` an integer indicating the number of kept axes `i,j` elements to extract (integer or empty): index of rows (i) and columns (j)

### Value

as.dudi and all the functions that use it return a list with the following components :

 `tab` a data frame with n rows and p columns `cw` column weights, a vector with n components `lw` row (lines) weights, a vector with p components `eig` eigenvalues, a vector with min(n,p) components `nf` integer, number of kept axes `c1` principal axes, data frame with p rows and nf columns `l1` principal components, data frame with n rows and nf columns `co` column coordinates, data frame with p rows and nf columns `li` row coordinates, data frame with n rows and nf columns `call` original call

### Author(s)

Daniel Chessel
Anne-Béatrice Dufour anne-beatrice.dufour@univ-lyon1.fr
Stéphane Dray stephane.dray@univ-lyon1.fr

### References

Escoufier, Y. (1987) The duality diagram : a means of better practical applications In Development in numerical ecology, Legendre, P. & Legendre, L. (Eds.) NATO advanced Institute, Serie G. Springer Verlag, Berlin, 139–156.

### Examples

```data(deug)
dd1 <- dudi.pca(deug\$tab, scannf = FALSE)
dd1
t(dd1)
is.dudi(dd1)
redo.dudi(dd1,3)
summary(dd1)
```

ade4 documentation built on Nov. 2, 2022, 1:07 a.m.