SDMtune (version 1.3.2)

randomFolds: Create Random Folds

Description

Create random folds for cross validation.

Usage

randomFolds(data, k, only_presence = FALSE, seed = NULL)

Value

list with two matrices, the first for the training and the second for the testing dataset. Each column of one matrix represents a fold with TRUE for the locations included in and FALSE excluded from the partition.

Arguments

data

SWD object that will be used to train the model.

k

integer. Number of fold used to create the partition.

only_presence

logical, if TRUE the random folds are created only for the presence locations and all the background locations are included in each fold, used manly for presence-only methods.

seed

integer. The value used to set the seed for the fold partition.

Author

Sergio Vignali

Details

When only_presence = FALSE, the proportion of presence and absence is preserved.

Examples

# Acquire environmental variables
files <- list.files(path = file.path(system.file(package = "dismo"), "ex"),
                    pattern = "grd", full.names = TRUE)
predictors <- terra::rast(files)

# Prepare presence and background locations
p_coords <- virtualSp$presence
bg_coords <- virtualSp$background

data <- prepareSWD(species = "Virtual species", p = p_coords, a = bg_coords,
                   env = predictors, categorical = "biome")

# Create 4 random folds splitting presence and absence locations
folds <- randomFolds(data, k = 4)

# Create 4 random folds splitting only the presence locations
folds <- randomFolds(data, k = 4, only_presence = TRUE)