Shannon: Shannon's diversity index (H')

In rasterdiv: Diversity Indices for Numerical Matrices

Shannon's diversity index (H')

Description

Computes Shannon's diversity index (H') on different classes of numeric matrices using a moving window algorithm.

Usage

Shannon(x, window=3, rasterOut=TRUE, np=1, na.tolerance=1.0, 
	cluster.type="SOCK", debugging=FALSE)

Arguments

x	input data may be a matrix, a Spatial Grid Data Frame, a RasterLayer or a list of these objects. In the latter case, only the first element of the list will be considered.
window	the side of the square moving window, it must be a odd numeric value greater than 1 to ensure that the target pixel is in the centre of the moving window. Default value is 3.
rasterOut	Boolean, if TRUE the output will be in RasterLayer format with x as template.
np	the number of processes (cores) which will be spawned. Default value is 1.
na.tolerance	a numeric value (0.0-1.0) which indicates the proportion of NA values that will be tolerated to calculate Shannon's index in each moving window over x. If the relative proportion of NA's in a moving window is bigger than na.tolerance, then the value of the window will be set as NA, otherwise Rao's index will be calculated considering the non-NA values. Default values is 1.0 (i.e., no tolerance for NA's).
cluster.type	the type of cluster which will be created. The options are "MPI" (calls "makeMPIcluster"), "FORK" and "SOCK" (call "makeCluster"). Default type is "SOCK".
debugging	a boolean variable set to FALSE by default. If TRUE, additional messages will be printed. For debugging only.

Details

Shannon's index (H') is calculated on a numerical matrix as H' = {∑_{i=1}^{R} p_i \times log(p_i)}, where R is the total number of categories (i.e., unique numerical values in the considered numerical matrix) and p is the relative abundance of each category.

Value

A numerical matrix with dimension {dim(x)}.

Note

Linux users need to install libopenmpi for MPI parallel computing. Linux Ubuntu users may try: apt-get update; apt-get upgrade; apt-get install mpi; apt-get install libopenmpi-dev; apt-get install r-cran-rmpi

Microsoft Windows users may need some additional work to use "MPI", see:
https://bioinfomagician.wordpress.com/2013/11/18/installing-rmpi-mpi-for-r-on-mac-and-windows/

Author(s)

Marcantonio Matteo [e-mail]
Martina Iannacito [e-mail]
Duccio Rocchini [e-mail]

References

Shannon, C.E. (1948). A mathematical theory of communication. Bell System Technical Journal, 27: 379-423, 623-656.

Examples

#Minimal example; compute Shannon's index  
a <- matrix(c(10,10,10,20,20,20,20,30,30),ncol=3,nrow=3)
shannon <- Shannon(x=a,window=3)

rasterdiv documentation built on Nov. 24, 2022, 9:07 a.m.