dudi.dec {ade4} | R Documentation

## Decentred Correspondence Analysis

### Description

performs a decentred correspondence analysis.

### Usage

    dudi.dec(df, eff, scannf = TRUE, nf = 2)

### Arguments

`df` | a data frame containing positive or null values
`eff` | a vector containing the reference distribution. Its length is equal to the number of rows of df
`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 `dec` and `dudi` (see `dudi`) containing also

`R` | sum of all the values of the initial table

### Author(s)

Daniel Chessel chessel@biomserv.univ-lyon1.fr

### References

Dolédec, S., Chessel, D. and Olivier J. M. (1995) L'analyse des correspondances décentrée: application aux peuplements ichtyologiques du haut-Rhône. Bulletin Français de la Pêche et de la Pisciculture, 336, 29–40.

### Examples

    data(ichtyo)
    dudi1 <- dudi.dec(ichtyo$tab, ichtyo$eff, scan = FALSE)
    sum(apply(ichtyo$tab, 2, function(x)
        chisq.test(x, p = ichtyo$eff/sum(ichtyo$eff))$statistic))
    sum(dudi1$eig) * sum(ichtyo$eff) # the same

    s.class(dudi1$li, ichtyo$dat, wt = ichtyo$eff/sum(ichtyo$eff))

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