rygg {benthos}R Documentation

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, data_frame, 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

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)
 )
 

[Package benthos version 1.3-6 Index]