Add boundary outlines to a spatial ggplot

Overlays spatial boundaries (from points or polygons) onto a ggplot2 object. The input can be either a data frame of boundary points or an sf object of POLYGON geometries. This function is typically used as an additive layer (+ addBoundary(...)) in conjunction with a base plot created using plotBoundary().

Usage

addBoundary(
  boundary = NULL,
  color_boundary = "black",
  linewidth_boundary = 1.5
)

Arguments

boundary

A data frame with columns x, y, and region_id or an sf object of POLYGON or LINESTRING geometries.

color_boundary

Color for boundary lines. Default is "black".

linewidth_boundary

Numeric. Line width for boundary outlines. Default is 1.5.

Value

A ggplot2::geom_path layer that can be added to an existing plot.

Examples

coords <- readRDS(system.file("extdata", "MouseBrainCoords.rds",
    package = "SpNeigh"
))

# Automatically get boundary for a cluster
boundary_points <- getBoundary(
    data = coords, one_cluster = 2,
    subregion_method = "dbscan",
    eps = 120, minPts = 10
)

# Plot with boundary overlay
plotBoundary(coords) + addBoundary(boundary_points)