[R] Canberra distance

[Stéphane Dray]

Frédéric Chiroleu wrote:
> PS : Be careful with function dudi.pca() from ade4 ; in values, "norm" 
> doesn't give you what is written in the help page : "norm" returns the 
> vector of standard deviations of initial variables when you choose 
> "normed" PCA and the vector of standard deviations of normed variables, 
> ie 1,  when you choose non "normed" PCA. We contacted authors of the 
> package unsuccessly to rectify the information.
>
>   
Dear Frederic,
AB Dufour told me that you send it an email, but it would be better to 
send an email to the adelist, as suggested in the DESCRIPTION file of 
the package.  BTW, this is a problem in the doc, that we will correct. 
If you consider:
dudi1<- dudi.pca(X)
dudi&$norm is a vector of values so that dudi1$tab[i,j] = 
(X[i,j]-dudi1$center[j])/dudi1$norm[j]

There is no bug, just a problem in the doc. Your "be careful with 
function dudi.pca" is a little bit exagerated I think. We will correct 
it but  there is sometimes some delay between a user request and its 
implementation in the package. Note that we have other activities than 
the development and the maintenance of ade4 (we have other scientific 
projects, to teach, to write papers, reviewing activities... like 
others)  and sometimes, we forget to answer to an email... sorry.
Our group provide free softwares, free documentation and teaching 
ressources for ecologists since a long time.  This is a free 
contribution, and I think that it merits more consideration than what 
your email suggests.

Cheers,



-- 
Stéphane DRAY (dray at biomserv.univ-lyon1.fr )
Laboratoire BBE-CNRS-UMR-5558, Univ. C. Bernard - Lyon I
43, Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
Tel: 33 4 72 43 27 57       Fax: 33 4 72 43 13 88
http://biomserv.univ-lyon1.fr/~dray/