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Create supercells as points

Source: R/sc_slic_points.R
sc_slic_points.Rd

Runs the SLIC workflow and returns supercell centers as points. Use iter = 0 to return the initial centers before iterations. For polygon outputs, use sc_slic(); for raster output, use sc_slic_raster()

Usage

sc_slic_points(
  x,
  step = NULL,
  compactness,
  dist_fun = "euclidean",
  avg_fun = "mean",
  clean = TRUE,
  minarea,
  iter = 10,
  step_unit = "cells",
  k = NULL,
  centers = NULL,
  metadata = FALSE,
  chunks = FALSE,
  iter_diagnostics = FALSE,
  verbose = 0
)

Arguments

x

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

step

The distance (number of cells) between initial centers (alternative is k).

compactness

A compactness value. Use sc_tune_compactness() to estimate it. Set compactness = "auto" to enable SLIC0-style adaptive compactness.

dist_fun

A distance function name or a custom function. Supported names: "euclidean", "jsd", "dtw", "dtw2d", or any method from philentropy::getDistMethods(). A custom function must accept two numeric vectors and return a single numeric value.

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

Should connectivity of the supercells be enforced?

minarea

Minimal size of a supercell (in cells).

iter

Number of iterations.

step_unit

Units for step. Use "cells" for pixel units or "map" for map units (converted to cells using raster resolution).

k

The number of supercells desired (alternative to step).

centers

Optional sf object of custom centers. Requires step.

metadata

Logical. Should metadata columns be kept?

chunks

Chunking option. Use FALSE for no chunking, TRUE for automatic chunking based on size, or a numeric value for a fixed chunk size (in number of cells per side).

iter_diagnostics

Logical. If TRUE, attaches iteration diagnostics as an attribute (iter_diagnostics) on the output. Only available when chunks are not used.

verbose

Verbosity level.

Value

An sf object with supercell center points and summary statistics

See also

sc_slic(), sc_slic_raster()

Examples

library(supercells)
vol = terra::rast(system.file("raster/volcano.tif", package = "supercells"))

# initial centers (only after local minima placement, no iterations)
init_pts = sc_slic_points(vol, step = 12, compactness = 1, iter = 0)
terra::plot(vol)
plot(sf::st_geometry(init_pts), add = TRUE, pch = 3, col = "red")


# final supercell centers
vol_pts = sc_slic_points(vol, step = 12, compactness = 1)
terra::plot(vol)
plot(sf::st_geometry(vol_pts), add = TRUE, pch = 16, col = "red")