Fits a hyperbolic function to the extinction simulation of
An object of class “bipartite”, usually generated by
Logical; want to see the graph?
Graphical parameters passed on to the
Function scales extinction sequences to values between 0 and 1 for each participant. The x-axis of the graph features the proportion of exterminated participants, while the y-axis depicts the proportion of secondary extinctions. Since these curves usually follow a hyperbolic function (see examples in Memmott et al. 2004), this is fitted to the data.
At present, only a function of type y \sim 1 - x^a is fitted (using
nls), i.e. without offset. While usually this
function provides very good fits, do check the graph and judge for yourself. Fitting this simple function makes its
parameter ‘a’ a measure of extinction vulnerability. The more gradual the secondary extinctions, the lower the absolute value of ‘a’. Or, phrased differently, large absolute values of ‘a’ indicate a very abrupt die-off, indicative of high initial redundancy in the network.
Returns one number, the exponent of the fitted hyperbolic model.
This function is not as vigorously tested as it should probably be. It worked fine for large networks, but small ones it may behave strangely, I fathom.
Carsten F. Dormann
Memmott, J., Waser, N. M. and Price, M. V. (2004) Tolerance of pollination networks to species extinctions. Proceedings of the Royal Society B 271, 2605–2611
second.extinct for generating the required input object.
1 2 3 4 5 6 7
Loading required package: vegan Loading required package: permute Loading required package: lattice This is vegan 2.4-4 Loading required package: sna Loading required package: statnet.common Attaching package: 'statnet.common' The following object is masked from 'package:base': order Loading required package: network network: Classes for Relational Data Version 1.13.0 created on 2015-08-31. copyright (c) 2005, Carter T. Butts, University of California-Irvine Mark S. Handcock, University of California -- Los Angeles David R. Hunter, Penn State University Martina Morris, University of Washington Skye Bender-deMoll, University of Washington For citation information, type citation("network"). Type help("network-package") to get started. sna: Tools for Social Network Analysis Version 2.4 created on 2016-07-23. copyright (c) 2005, Carter T. Butts, University of California-Irvine For citation information, type citation("sna"). Type help(package="sna") to get started. This is bipartite 2.08 For latest changes see versionlog in ?"bipartite-package". For citation see: citation("bipartite"). Have a nice time plotting and analysing two-mode networks. Attaching package: 'bipartite' The following object is masked from 'package:vegan': nullmodel exponent 1.302755
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.