fisher {untb} | R Documentation |
Various functions connected to Fisher's logseries including creation of synthetic datasets and estimation of Fisher's alpha
fishers.alpha(N, S, give=FALSE) fisher.ecosystem(N, S, nmax, alpha=NULL, c=0)
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 from
N and S . |
give |
In function fishers.alpha() , Boolean variable with
default FALSE meaning to return alpha, and TRUE
meaning to return a list containing x and alpha . |
nmax |
In function fisher.ecosystem() , the maximum number
of species abundance classes to consider |
c |
In function fisher.ecosystem() , the rare species
advantage term |
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.
Robin K. S. Hankin
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
fishers.alpha(N=100000,S=100) #compare the Table value: 100000/10^3.95991