mobr (version 3.0.0)

calc_PIE: 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)

Value

either a single PIE value or vector of PIE values.

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).

Author

Dan McGlinn, Thore Engel

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.

References

Hurlbert, S. H. (1971) The nonconcept of species diversity: a critique and alternative parameters. Ecology 52, 577-586.

See Also

calc_SPIE

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)