Simpson's diversity index (Diversity metric)
lsm_l_sidi(landscape, directions = 8)tibble
Raster* Layer, Stack, Brick, SpatRaster (terra), stars, or a list of rasterLayers.
The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case).
$$SIDI = 1 - \sum \limits_{i = 1}^{m} P_{i}^{2}$$ 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.
None
0 <= SIDI < 1
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
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: https://www.umass.edu/landeco/
Simpson, E. H. 1949. Measurement of diversity. Nature 163:688
lsm_c_pland,
lsm_l_pr