Convert boundary polygons to boundary point coordinates

Extracts the vertex coordinates (x, y) of boundary geometries from an sf object containing POLYGON or LINESTRING features. This is useful for recovering the original boundary points from smoothed or labeled polygonal regions.

Usage

boundaryPolyToPoints(boundary_poly = NULL)

Arguments

boundary_poly

An sf object containing only POLYGON or LINESTRING geometries. Must include a region_id column for labeling subregions.

Value

A data frame with columns x, y, and region_id, containing the vertex coordinates of the boundary geometries.

Examples

# Load coordinates and generate boundary
coords <- readRDS(system.file("extdata", "MouseBrainCoords.rds",
    package = "SpNeigh"
))
boundary_points <- getBoundary(data = coords, one_cluster = 2)
boundary_polys <- buildBoundaryPoly(boundary_points)

# Convert back to boundary points
boundary_pts <- boundaryPolyToPoints(boundary_polys)
#> Warning: repeating attributes for all sub-geometries for which they may not be constant
head(boundary_pts)
#>            x        y region_id
#> 1   1698.220 3196.813         1
#> 1.1 1718.113 3201.256         1
#> 1.2 1718.264 3211.133         1
#> 1.3 1732.328 3227.695         1
#> 1.4 1707.091 3262.311         1
#> 1.5 1698.292 3289.946         1