Description

Simpson's evenness index (Diversity metric)

Usage

Arguments

Details

SIEI = \frac{1 - ∑ \limits_{i = 1}^{m} P_{i}^{2}} {1 - \frac{1} {m}}

where P_{i} is the proportion of class i and m is the number of classes.

SIEI is a 'Diversity metric'. The metric is widely used in biodiversity and ecology. It is the ratio between the actual Simpson's diversity index and the theoretical maximum Simpson's diversity index.

Units

None

Range

0 < SIEI <= 1

Behaviour

Equals SIEI = 0 when only one patch is present and approaches SIEI = 1 when the number of class types increases while the proportions are equally distributed

Value

tibble

References

McGarigal, K., SA Cushman, and E Ene. 2012. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical and Continuous Maps. Computer software program produced by the authors at the University of Massachusetts, Amherst. Available at the following web site: http://www.umass.edu/landeco/research/fragstats/fragstats.html

Simpson, E. H. 1949. Measurement of diversity. Nature 163:688

See Also

lsm_c_pland, lsm_l_pr

Examples