Modified Simpson's evenness index (Diversity metric)
Arguments
- landscape
A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
- directions
The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case).
Details
$$MSIEi = \frac{- \ln \sum \limits_{i = 1}^{m} P_{i}^{2}} {\ln m}$$ where \(P_{i}\) is the landscape area proportion of class i. MSIEI is a 'Diversity metric'.
References
McGarigal K., SA Cushman, and E Ene. 2023. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical Maps. Computer software program produced by the authors; available at the following web site: https://www.fragstats.org
Simpson, E. H. 1949. Measurement of diversity. Nature 163:688
Pielou, E. C. 1975. Ecological Diversity. Wiley-Interscience, New York.