heterog {heterogen}

Heterogeneity (rasters)

Description

The heterog function is designed to calculate environmental heterogeneity metric from a raster stack dataset. This function aids in assessing the spatial variation and diversity of environmental variables within the raster data, providing valuable insights into the heterogeneity of the study area.

Usage

heterog(
  datastack,
  bandwidth = 0.3,
  tolerance = 5,
  nprocess = 1000,
  parallel = FALSE,
  ncores = 2,
  normalized = FALSE,
  method = "iter",
  dirds = "rds"
)

Arguments

datastack

SpatRaster class. The input raster stack representing environmental variables. Each layer in the stack corresponds to a different environmental variable, and the function calculates heterogeneity based on the variability across these layers.

bandwidth

The bandwidth for the spatial weighting function.

tolerance

The tolerance for spatial weight computation.

nprocess

(Optional) The number of iterations for calculating the principal components. Default is set to 1000.

parallel

(Optional) A logical value indicating whether to run the computation in parallel. If TRUE, multiple cores will be used for processing. Default is FALSE.

ncores

(Optional) The number of cores to be used for parallel computation. Only applicable if parallel is set to TRUE. Default is 4.

normalized

(Optional) A logical value indicating whether the input data should be normalized before performing GWPCA. Default is FALSE, meaning the data will not be normalized. Take in account that core function performs correlation analysis in order to normalize the input variables.

method

The method used for GWPCA computation. It can take one of the following values. local Performs GWPCA locally and will save each iteration on .rds files. Recommended for large-scale data sets. inter Uses RAM memory to . Default is inter.

dirds

(Optional) The directory where the results will be saved in RDS format. Default is rds.

Value

A SpatHetero object

• hetero A heterogeneity layer

• matrix A Matrix of eigenvalues

• rasters A complete set of heterogeneity layers for each component

Examples

# Case 01: South
path <- system.file("extdata","south", package="heterogen")
south_rast <- terra::rast(list.files(path, full.names = TRUE, 
pattern = '.tif'))

south_het <- heterog(south_rast, parallel = TRUE, 
bandwidth = 0.1, tolerance = 10)
plot(south_het)



# Case 02: North
path <- system.file("extdata","north", package="heterogen")
north_rast <- terra::rast(list.files(path, full.names = TRUE, 
pattern = '.tif'))

north_het <- heterog(north_rast, parallel = TRUE,
bandwidth = 0.1, tolerance = 10)
plot(north_het)