simpson

simpson_

data in a <code>data.frame</code>, <code>data_frame</code>, 
<code>data.table</code>, database etc.

.data

name of column in <code>.data</code> containing taxa

taxon

name of column in <code>.data</code> containing counts

count

The probability that two inidividuals selected at random (with replacement, 
Hurlbert, 1971, p.579) from a sample will belong to the same species. For
an infinite sample Simpson's Index is given by (Peet, 1974):
$$\lambda = \sum_{i=1}^S p_i^2$$
For a finite sample by:
$$L = \sum_{i=1}^S \frac{n_i (n_i-1)}{N (N-1)}$$
where $p_i$ the proportion of the individuals in species $i$, 
$n_i$ the number of individuals in species 
$i$ (relative <code><a rd-options="" href="/link/abundance?package=benthos&version=1.3-4" data-mini-rdoc="benthos::abundance">abundance</a></code>), and $N$ the total number 
of individuals (<code><a rd-options="" href="/link/total_abundance?package=benthos&version=1.3-4" data-mini-rdoc="benthos::total_abundance">total_abundance</a></code>). The finite sample case 
has been implemented in function <code>simpson</code> (and <code>simpson_</code>).

Preprocessing tools and biodiversity measures
(species abundance, species richness, population heterogeneity and
sensitivity) for analysing marine benthic data. See Van Loon et al.
(2015) <doi:10.1016/j.seares.2015.05.002> for an application of
these tools.

Dennis Walvoort

benthos

Marine Benthic Ecosystem Analysis

simpson function

<ul>
<li><code>simpson_</code>: version suitable for calling from a function
(see package lazyeval).</li>
</ul>

Functions

The probability that two inidividuals selected at random (with replacement, 
Hurlbert, 1971, p.579) from a sample will belong to the same species. For
an infinite sample Simpson's Index is given by (Peet, 1974):
$$\lambda = \sum_{i=1}^S p_i^2$$
For a finite sample by:
$$L = \sum_{i=1}^S \frac{n_i (n_i-1)}{N (N-1)}$$
where $p_i$ the proportion of the individuals in species $i$, 
$n_i$ the number of individuals in species 
$i$ (relative <code><a rd-options='' href='abundance'>abundance</a></code>), and $N$ the total number 
of individuals (<code><a rd-options='' href='total_abundance'>total_abundance</a></code>). The finite sample case 
has been implemented in function <code>simpson</code> (and <code>simpson_</code>).

simpson: Simpson's Measure of Concentration

Description

Usage

Arguments

Value

Functions

References

See Also

Examples