Scilab function

contract_edge - contracts edges between two nodes

### Calling Sequence

  `g1 = contract_edge(i,j,g)`

### Parameters

- `i` : integer, number of start or end node of edge
- `j` : integer, number of end or start node of edge
- `g` : graph list
- `g1` : graph list of the new graph

### Description

`contract_edge` returns the graph `g1`, the edges between the nodes number `i` and `j` being deleted, the nodes being reduced to one node with the same name as node `i` and located at the middle point between the 2 previous nodes.

### Examples

    ta=[1 1 2 2 2 3 4 5 5 7 8 8 9 10 10 10 10 10 11 12 13 13 13 14 15 16 16 17 17];
    he=[2 10 3 5 7 4 2 4 6 8 6 9 7 7 11 13 13 15 12 13 9 10 14 11 16 1 17 14 15];
    g=make_graph('foo',1,17,ta,he);
    g('node_x')=[283 163 63 57 164 164 273 271 339 384 504 513 439 623 631 757 642];
    g('node_y')=[59 133 223 318 227 319 221 324 432 141 209 319 428 443 187 151 301];
    show_graph(g);
    g1=contract_edge(10,13,g);
    show_graph(g1,'new');

### See Also

`add_edge` `add_node` `delete_arcs` `delete_nodes`