Truncating polygons in R
Gregory Snow wrote:
I have one suggested extension to Barry's idea. With Barry's idea the polygons will all be inside the square, but there will be some area in the square that is not inside any of the polygons. If you want the entire square to be included within the polygons then take Barrys Idea of projecting the points perpendicular to the sides, but instead of projecting them onto the sides, project them beyond that side so that they are the same distance from the side of the square. Then the set of points that are equal distance from the projected point and the original point will fall along the border of the square.
Nice. I implemented my method this afternoon and one thing I hadn't expected was that it can generate disconnected polygons! If you have a point over in a corner with not much near it the guard points round the edges can cut it off from the rest of the data points. Obviously the tessalation as a whole is connected, but when you drop the guard points' polygons you get an island. I suspect Greg's technique can't do that since the whole square is filled with polygons from your data points. Fun. Barry