rygg: Rygg's Index of Diversity

In benthos: Marine Benthic Ecosystem Analysis

Rygg's Index of Diversity

Description

Rygg's index of diversity is given by

SN = ln(S)/(ln(ln(N)))

The adjusted version of Rygg's index which gives more consistent values for smaller S=2, N=2, N=3 and S=3, N=3 is

SN = ln(S)/(ln(ln(N+1)+1))

Usage

rygg(.data = NULL, taxon, count, adjusted = FALSE)

rygg_(.data = NULL, taxon, count, adjusted = FALSE)

Arguments

.data	data in a data.frame, tibble, data.table, database etc.
taxon	taxa names (character)
count	counts (numeric)
adjusted	(defaults to FALSE)

Value

Rygg's index of diversity (numeric vector of length 1)

Functions

• rygg_(): version suitable for calling from a function (see package lazyeval).

Note

Rygg's index is not defined for N=exp(1). For N <= exp(1), rygg returns NA_real_.

References

Rygg, B. (2006). Developing indices for quality-status classification of marine soft-bottom fauna in Norway. Norwegian Institute for Water Research, Oslo, Norway. NIVA Report SNO 5208-2006.

Examples

 rygg(
     taxon = c("Euspira pulchella", "Nephtys cirrosa"), 
     count = c(4, 6)
 )
 

benthos documentation built on Aug. 22, 2022, 5:07 p.m.