I'm trying to come up with a way to order 'random' (poly) lines, knowing only the coordinates of the vertices (and, obviously, which vertices belong to any given line). I'm not a mathematician or geometrician, but I have a feeling there must be an 'easy' way to do this! Would probably have to break down the problem something like this: 1) Somehow, calculate a 'direction' for the ordering (e.g., vertical lines could be ordered left-to-right or right-to-left, horizontal lines top-to-bottom or bottom-to-top, polygons inside-to-outside etc.) 2) Decompose the lines to some simplified property (the centroid?) that will put them "in order" along the direction from 1). Any suggestions gratefully received!