如何获得多边形的中心点，必定在这些多边形（R，sp）中

Question

How to get central points for polygons that would fall necessarily in those polygons? Just getting the centroid will fall outside the polygon for many not convex polygons.

Ideally the polygons would be SpatialPolygons in R and the central points would also be returned as an sp object.

Answer 1

You can use GetCentralPoints from the spatDataManagement package . That is derived from this answer somewhere else on the web.

Executing the example would return:

plot(woods[1:5,])
# the centroids
plot(GetCentroids(woods[1:5,]),add=T)
# the central points guaranteed to be in the polygons
plot(GetCentralPoints(woods[1:5,]),add=T,col="blue")
legend("bottomright",legend=c("Centroids","Central points"),col=c("black","blue"),pch="+")

You get (note the bottom polygon)