untb (version 1.0-20)

preston: Preston diagram of an ecosystem

Description

Gives a standard Preston diagram for an ecosystem.

Usage

preston(x,n=8,original=FALSE)

Arguments

x
Ecosystem vector that is coerced to class count
n
An integer specifying the number of species abundance classes to use. Must be greater than 1.
original
Boolean, with default FALSE meaning to use the nonoverlapping technique discussed below, and TRUE meaning to use Preston's original formulation.

Value

  • Function preston() returns an object of class preston.

Details

The Preston diagram is a table showing the number of species having abundances in specified abundance classes. Consider the following Preston diagram, created with original = FALSE: 1 2 3-4 5-8 9-16 17-32 33-64 65-Inf number of species 10 5 7 5 1 5 4 0

This shows that there are 10 species with abundance 1 (that is, singletons); 5 species with abundance 2; 7 species with abudance 3-4; 5 species with abundance 5-8, and so on.

Setting argument original to TRUE means to follow Preston (1948) and count any species with an abundance on the boundary between two adjacent abundance classes as being split 50-50 between the classes. Thus the fourth class would be $\phi_4/2+\phi_5+\phi_6+\phi_7+\phi_8/2$ where $\phi_i$ is the number of species with abundance $i$ (given by phi(x)).

References

F. W. Preston 1948. The Commonness, and Rarity, of Species. Ecology 29(3):254-283

See Also

phi

Examples

Run this code
preston(untb(start=rep(1,100), prob=0.01, gens=1000, keep=FALSE))

data(butterflies)
preston(butterflies)
preston(butterflies,original=TRUE)


data(copepod)
preston(copepod)
preston(copepod, n=21)

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