# dudi.coa: Correspondence Analysis In ade4: Analysis of Ecological Data: Exploratory and Euclidean Methods in Environmental Sciences

## Description

performs a correspondence analysis.

## Usage

 `1` ```dudi.coa(df, scannf = TRUE, nf = 2) ```

## Arguments

 `df` a data frame containing positive or null values `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

## Value

returns a list of class `coa` and `dudi` (see dudi) containing

 `N` the sum of all the values of the initial table

## Author(s)

Daniel Chessel
Anne-Béatrice Dufour anne-beatrice.dufour@univ-lyon1.fr

## References

Benzécri, J.P. and Coll. (1973) L'analyse des données. II L'analyse des correspondances, Bordas, Paris. 1–620.

Greenacre, M. J. (1984) Theory and applications of correspondence analysis, Academic Press, London.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20``` ```data(rpjdl) chisq.test(rpjdl\$fau)\$statistic rpjdl.coa <- dudi.coa(rpjdl\$fau, scannf = FALSE, nf = 4) sum(rpjdl.coa\$eig)*rpjdl.coa\$N # the same if(adegraphicsLoaded()) { g1 <- s.label(rpjdl.coa\$co, plab.cex = 0.6, lab = rpjdl\$frlab, plot = FALSE) g2 <- s.label(rpjdl.coa\$li, plab.cex = 0.6, plot = FALSE) cbindADEg(g1, g2, plot = TRUE) } else { par(mfrow = c(1,2)) s.label(rpjdl.coa\$co, clab = 0.6, lab = rpjdl\$frlab) s.label(rpjdl.coa\$li, clab = 0.6) par(mfrow = c(1,1)) } data(bordeaux) db <- dudi.coa(bordeaux, scan = FALSE) db score(db) ```

### Example output

```X-squared
7323.597
Warning message:
In chisq.test(rpjdl\$fau) : Chi-squared approximation may be incorrect
[1] 7323.597
Duality diagramm
class: coa dudi
\$call: dudi.coa(df = bordeaux, scannf = FALSE)

\$nf: 2 axis-components saved
\$rank: 3
eigen values: 0.5906 0.1102 0.03109
vector length mode    content
1 \$cw    4      numeric column weights
2 \$lw    5      numeric row weights
3 \$eig   3      numeric eigen values

data.frame nrow ncol content
1 \$tab       5    4    modified array
2 \$li        5    2    row coordinates
3 \$l1        5    2    row normed scores
4 \$co        4    2    column coordinates
5 \$c1        4    2    column normed scores
other elements: N
```

ade4 documentation built on March 26, 2020, 6:19 p.m.