# [R] canonical correspondence analysis

Prof Brian Ripley ripley at stats.ox.ac.uk
Mon Feb 19 10:52:01 CET 2001

```> Date: Mon, 19 Feb 2001 10:28:40 +0100
> To: r-help at stat.math.ethz.ch
> From: Stephane Dray <dray at biomserv.univ-lyon1.fr>
> Subject: Re: [R] canonical correspondence analysis
>
> Canonical Correspondence Analysis is an ordination method widely used
> among ecologists (ter Braak). This method allow to analyze two tables
> (L and E) which have the same number of rows. It is a correspondence
> analysis of table L with linear constraint from E (multiple linear
> regression) : the row score are linear combination of variables of E.
> The columns scores are obtained by weighting averaging. CCA finds
> linear combination of external variables (E) to obtain a row score
> which maximizes the between-variance of columns score (obtained by
> averaging) . Ter Braak called it "canonical" correspondence analysis
> because it analyses two tables (like canonical analysis) but we
> preferred the more explicit name of correspondence analysis with
> respect to instrumental variables".
> But .... in a theoretical point of view, CCA could be considered as a
> canonical correlation analysis (the same links as between
> correspondence analysis and canonical correlation analysis). I m just
> writing a R function to perform Correspondence analysis with or
> without linear contstraints (CA, CCA on row or column, Double CCA on
> rows and columns) and to make the graphical representation (bi or
> triplot).
> I will be happy to communicate this function to anyone which is intersted in.

Can we encourage you to submit it as a package to CRAN?   Sounds
as if a number of people would be interested.

Just one point: please avoid CCA, as it is unclear if it is

canonical correspondence analysis
canonical correlation analysis

--
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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