Generate Background Sample Indices

Randomly selects valid (non-NODATA) cells from a reference grid for use as background points in MaxEnt modeling.

Usage

maxent_background_indices(grid, n = 10000L, seed = NULL)

Arguments

grid

External pointer to a GridFloat object used as a reference (e.g. an environmental layer). Only cells with valid data are eligible.

n

Integer: number of background points to sample (default 10000L).

seed

Integer or NULL: random seed for reproducibility. If NULL (default), no seed is set.

Value

A named list with:

rows

Integer vector of row indices (0-based).

cols

Integer vector of column indices (0-based).

indices

Integer vector of 0-based flat indices (row * ncols + col), suitable for maxent_featured_space.

Examples

if (FALSE) { # \dontrun{
dim <- maxent_dimension(100, 100, -120, 35, 0.1)
grid <- maxent_grid(dim, "env1")
bg <- maxent_background_indices(grid, n = 5000, seed = 42)
bg$indices  # 0-based flat indices for FeaturedSpace
} # }