calc_PIE {mobr} | R Documentation |
Calculate probability of interspecific encounter (PIE)
Description
calc_PIE
returns the probability of interspecific encounter (PIE)
which is also known as Simpson's evenness index and Gini-Simpson index.
Usage
calc_PIE(x, replace = FALSE)
Arguments
x |
can either be a: 1) mob_in object, 2) community matrix-like object in which rows represent plots and columns represent species, or 3) a vector which contains the abundance of each species. |
replace |
if TRUE, sampling with replacement is used. Otherwise, sampling without replacement (default). |
Details
By default, Hurlbert's (1971) sample-size corrected formula is used:
PIE = N /(N - 1) * (1 - sum(p_i^2))
where N is the total number of individuals and p_i
is the relative
abundance of species i. This formulation uses sampling without replacement
(replace = F
) For sampling with replacement (i.e., the sample-size
uncorrected version), set replace = T
.
In earlier versions of mobr
, there was an additional argument
(ENS
) for the conversion into an effective number of species (i.e
S_PIE). Now, calc_SPIE
has become its own function and the
(ENS
) argument is no longer supported . Please, use calc_SPIE
instead.
Value
either a single PIE value or vector of PIE values.
Author(s)
Dan McGlinn, Thore Engel
References
Hurlbert, S. H. (1971) The nonconcept of species diversity: a critique and alternative parameters. Ecology 52, 577-586.
See Also
Examples
data(inv_comm)
calc_PIE(inv_comm)
calc_PIE(inv_comm, replace = TRUE)
calc_PIE(c(23,21,12,5,1,2,3))
calc_PIE(c(23,21,12,5,1,2,3), replace = TRUE)