Detects compartments

Description

Finds number of compartments, based on multivariate ordination techniques, and labels interactions according to the compartment they belong to.

Usage

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compart(web)

Arguments

web

A bipartite interaction web, i.e.~a matrix with higher (cols) and lower (rows) trophic levels.

Details

Internal function, to be called by networklevel.

Value

Returns a list with two entries:

cweb

A matrix similar to web, but now with compartment numbers instead of interaction values.

ncompart

The number of compartments.

Note

Note that up to (and including) version 0.85 we used a code based on correspondence analysis (see Lewinsohn et al. 2006). This is, however, faulty for webs with many same-linked species. Hence we resorted to a brute-force search for compartments, which is orders of magnitude slower, but at least works correctly. Only in version 1.18 Juan M. Barreneche eventually found a solution that is fast and works with ties!

Author(s)

Juan M. Barreneche <jumanbar@gmail.com>, but please co-copy comments/questions to package maintainer: Carsten F. Dormann <carsten.dormann@biom.uni-freiburg.de>

References

Lewinsohn, T. M., P. I. Prado, P. Jordano, J. Bascompte, and J. M. Olesen (2006) Structure in plant-animal interaction assemblages. Oikos 113, 174–184

See Also

See also networklevel.

Examples

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# make a nicely comparted web:
web <- matrix(0, 10,10)
web[1,1:3] <- 1 
web[2,4:5] <- 1 
web[3:7, 6:8] <- 1
web[8:10, 9:10] <- 1
web <- web[-c(4:5),] #oh, and make it asymmetric!
web <- web[,c(1:5, 9,10, 6:8)] #oh, and make it non-diagonal
compart(web)

# or, standard, use Safariland as example:
data(Safariland)
compart(Safariland)

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