SLIC convergence diagnostics

Runs SLIC and returns per-iteration mean combined distance. The output can be plotted directly with plot().

Usage

sc_slic_convergence(
  x,
  step = NULL,
  compactness,
  dist_fun = "euclidean",
  avg_fun = "mean",
  clean = FALSE,
  minarea,
  iter = 10,
  k = NULL,
  centers = NULL,
  verbose = 0
)

Arguments

x

An object of class SpatRaster (terra) or class stars (stars).

step

Initial center spacing (alternative is k). Provide a plain numeric value for cell units, or use use_meters() for map-distance steps in meters (automatically converted to cells using raster resolution).

compactness

A compactness value. Use sc_tune_compactness() to estimate it. Use use_adaptive() to enable adaptive compactness based on local feature-space distances.

dist_fun

A supported distance name from sc_list_distances() or a custom function that takes two numeric vectors and returns one finite, nonnegative value. Smaller values must mean greater similarity.

avg_fun

An averaging function name or custom function used to summarize values within each supercell. Supported names: "mean" and "median". A custom function must accept a numeric vector and return a single numeric value.

clean

Connectivity cleaning is not applied to convergence diagnostics. Setting this to TRUE produces a warning and is otherwise ignored.

minarea

Ignored because connectivity cleaning is not applied.

iter

Number of iterations.

k

The number of supercells desired (alternative to step).

centers

Optional sf object of custom centers. Requires step.

verbose

Verbosity level.

Value

A data frame with class sc_slic_convergence and columns:

iter

Iteration number.

mean_distance

Mean combined distance across assigned cells at each iteration.

See also

sc_slic(), plot()

Examples

library(supercells)
vol = terra::rast(system.file("raster/volcano.tif", package = "supercells"))
conv = sc_slic_convergence(vol, step = 8, compactness = 5, iter = 10)
plot(conv)