fisher
From untb v1.7-2
by Robin K S Hankin
Various functionality to implement Fisher's logseries
Various functions connected to Fisher's logseries including creation of synthetic datasets and estimation of Fisher's alpha
- Keywords
- math
Usage
fishers.alpha(N, S, give=FALSE)
fisher.ecosystem(N, S, nmax, alpha=NULL, c=0)
Arguments
- N
- Size of the ecosystem. In the case of
fisher.ecosystem()
, the expected size of the ecosystem - S
- Number of species in ecosystem
- alpha
- In function
fisher.ecosystem()
, Fisher's $alpha$. If not supplied, it will be calculated fromN
andS
. - give
- In function
fishers.alpha()
, Boolean variable with defaultFALSE
meaning to return alpha, andTRUE
meaning to return a list containingx
andalpha
. - nmax
- In function
fisher.ecosystem()
, the maximum number of species abundance classes to consider - c
- In function
fisher.ecosystem()
, the rare species advantage term
Details
Function fishers.alpha()
solves for $alpha$ given
$N$ and $S$, as per Fisher's table 9, p55.
Given $N$ and $S$ (or $alpha$), function
fisher.ecosystem()
generates a Fisherian ecosystem
with expected size $N$ and expected species count $S$.
References
R. A. Fisher and A. S. Corbet and C. B. Williams 1943. The relation between the number of species and the number of individuals in a random sample of an animal population, Journal of Animal Ecology, volume 12, pp 42--58
Examples
fishers.alpha(N=100000,S=100)
#compare the Table value:
100000/10^3.95991
Community examples
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