bipartite (version 0.7)

shuffle.web: Shuffle web entries

Description

Shuffles (= relocates) entries in a web matrix whilst maintaining the dimensionality.

Usage

shuffle.web(web, N)

Arguments

web

An interaction matrix.

N

Number of desired shuffled matrices.

Value

• A list of N randomised matrices with the same dimensions as the initial web.

encoding

latin1

Details

This function is designed to behave similar to r2dtable, i.e. it returns a list of randomised matrices. In contrast to r2dtable is does not keep marginal sums constant! This function is thought of as a nullmodel for the analysis of bipartite webs. It keeps two web properties constant: The number of interactions and the number of links (and hence connectance). A comparison of shuffle.web- and r2dtable-based webs allows to elucidate the effect of marginal sums.

References

This nullmodel can be thought of as a quantitative version of Fortuna & Bascompte (2006) null model 1: Fortuna, M. A., and J. Bascompte. 2006. Habitat loss and the structure of plant-animal mutualistic networks. Ecology Letters 9: 281-286. For a very nice and thorough overview of nullmodels in general see: Gotelli, N. J., and G. R. Graves. 1996. Null Models in Ecology. Smithsonian Institution Press, Washington D.C. For nullmodels and their application to webs/networks see, e.g.: V�zquez, D. P., and M. A. Aizen. 2003. Null model analyses of specialization in plant-pollinator interactions. Ecology 84: 2493-2501. V�zquez, D. P., C. J. Meli�n, N. M. Williams, N. Bl�thgen, B. R. Krasnov, and R. Poulin. 2007. Species abundance and asymmetric interaction strength in ecological networks. Oikos 116: 1120-1127.

See Also

r2dtable

Examples

data(Safariland)

shuffle.web(Safariland, N=2)