cut_sppoly: Cuts Polygons object into 2 lines of which it returns the...
In choisy/sptools: Additional Functions for Spatial* Objects

Each polygon is cut between the points of the polygons that are closest to pt1 and pt2

1	cut_sppoly(sppoly, pt1, pt2)

`sppoly`	A Polygon object as defined the sp package.
`pt1`	A single-point SpatialPoint object as defined in the sp package.
`pt2`	A single-point SpatialPoint object as defined in the sp package.

library(sf)

# SpatialPolygonsDataFrame
vn <- sf::as_Spatial(gadmVN::gadm(level = "province"))
# SpatialPoints
stations <- as(imhen::stations, "Spatial")
stations <- df2splist(as.data.frame(stations@coords))
cut_sppoly(vn, stations[[1]], stations[[2]])