line_graph - graph with nodes corresponding to edges
line_graph returns the graph g1 with the nodes corresponding to the edges of the graph g. g1 is defined in the following way: - its nodes correspond to the edges of g - 2 nodes of the new graph are adjacent if and only if the corresponding edges of the graph g are adjacent.
The coordinates of the nodes of g1 are given by the middle points of the corresponding edges of g.
ta=[1 1 2 4 4 5 6 7 2 3 5 1];
he=[2 6 3 6 7 8 8 8 4 7 3 5];
g=make_graph('foo',0,8,ta,he);
g('node_x')=[281 284 360 185 405 182 118 45];
g('node_y')=[262 179 130 154 368 248 64 309];
show_graph(g);
g1=line_graph(g);
show_graph(g1,'new');