Description
Find the Pole of Inaccessibility (Visual Center) of a Polygon.
Description
A wrapper around the C++ library 'polylabel' from 'Mapbox', providing an efficient routine for finding the approximate pole of inaccessibility of a polygon, which usually serves as an excellent candidate for labeling of a polygon.
README.md
polylabelr
polylabelr is an R wrapper for the polylabel package from Mapbox. It currently contains a single function, poi() that finds the pole of inaccessibility of a polygon, which usually makes for a good place to put a label on a polygon—hence the name.
Usage
# a concave polygon
x <- c(0, 4, 1, 6, 7, 7, 0, 0)
y <- c(0, 0, 1, 2, 1, 3, 2, 0)
# locate the pole of inaccessibility
p <- polylabelr::poi(x, y, precision = 0.01)
plot.new()
plot.window(range(x, na.rm = TRUE), range(y, na.rm = TRUE))
polypath(x, y, col = "grey", border = FALSE)
points(p)
Installation
CRAN version
install.packages("eulerr")
Development version
remotes::install_github("jolars/polylabelr")
Modifications
The source code from polylabel and geometry.hpp has been modified in a few ways to compile properly with c++11 using the standard flags required by CRAN policies. polylabel has also been modified to return the distance from the chosen point to the enclosing polygon, in case it is of value to users.
Versioning
polylabelr uses semantic versioning.