Hill {rasterdiv}

Hill's index of diversity - Hill numbers (D)

Description

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

Usage

Hill(
  x,
  window = 3,
  alpha = 1,
  base = exp(1),
  rasterOut = TRUE,
  np = 1,
  na.tolerance = 1,
  cluster.type = "SOCK",
  debugging = FALSE
)

Arguments

x

Input data may be a matrix, a Spatial Grid Data Frame, a SpatRaster, 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 an odd numeric value greater than 1 to ensure that the target pixel is in the centre of the moving window. Default value is 3.

alpha

Order of the Hill number to compute the index. If alpha is a vector with length greater than 1, then the index will be calculated over x for each value in the sequence.

base

The logarithm base for the calculation, default is natural logarithm.

rasterOut

Boolean; if TRUE, the output will be in SpatRaster format with x as the template.

np

The number of processes (cores) which will be spawned. Default value is 1.

na.tolerance

A numeric value between 0.0 and 1.0, which indicates the proportion of NA values that will be tolerated to calculate Hill'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, Hill's index will be calculated considering the non-NA values. Default value is 1.0 (i.e., full tolerance for NA's).

cluster.type

The type of cluster which will be created. 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 purposes.

Details

Hill numbers ({}^qD) are calculated on numerical matrices as {}^qD = (\sum_{i=1}^{R} {p^q}_i)^{1/(1-q)}, where q is the order of the Hill number, R is the total number of categories (i.e., unique numerical values in a numerical matrix), and p is the relative abundance of each category. When q=1, Shannon.R is called to calculate exp(H^1) instead of the indefinite {}^1D. If q > 2*10^9, BergerParker.R is called to calculate 1/{{}^\infty D}. Hill numbers of low order weight more rare categories, whereas Hill numbers of higher order weight more dominant categories.

Value

A list of matrices of dimension dim(x) with length equal to the length of alpha.

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". For more details, see: https://bioinfomagician.wordpress.com/2013/11/18/installing-rmpi-mpi-for-r-on-mac-and-windows/

References

Hill, M.O. (1973). Diversity and evenness: a unifying notation and its consequences. Ecology 54, 427-432.

See Also

BergerParker, Shannon

Examples

# Minimal example; compute Hill's index with alpha 1:5 
a <- matrix(c(10,10,10,20,20,20,20,30,30),ncol=3,nrow=3)
hill <- Hill(x=a,window=3,alpha=1:5)