Description

Simpson's diversity index (Diversity metric)

Usage

Arguments

Details

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

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

SIDI is a 'Diversity metric'. It is widely used in biodiversity and ecology. It is less sensitive to rare class types than lsm_l_shdi. It can be interpreted as the probability that two randomly selected cells belong to the same class.

Units

None

Range

0 <= SIDI < 1

Behaviour

Equals SIDI = 0 when only one patch is present and approaches SIDI < 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