GVPR script to extract subgraphs

reduce.g

BEGIN{
	if (ARGC != 2) {
		print("This script takes exactly two parameter. 1: name of node, 2: number of hops");
		exit(1);
	}
	
	void reduce_in(graph_t _g, node_t _n, edge_t _e, int _d){
		_e = fstin(_n);
		while (_e != NULL) {
			clone(_g, _e);
			if (_d < atoi(ARGV[1])) {
			  reduce_in(_g, _e.tail, NULL, _d + 1);
			}
			_e = nxtin(_e);
		}
	}

	void reduce_out(graph_t _g, node_t _n, edge_t _e, int _d){
		_e = fstout(_n);
		while (_e != NULL) {
			clone(_g, _e);
			if (_d < atoi(ARGV[1])) {
			  reduce_out(_g, _e.head, NULL, _d + 1);
			}
			_e = nxtout(_e);
		}
	}
}

BEG_G {
	graph_t g = graph("G", "S");
	g.rankdir = "RL";
}


N [name==ARGV[0]] {
	node_t n = clone(g, $);
	n.color="red";
	reduce_in(g, $, NULL, 1);
	reduce_out(g, $, NULL, 1);
}

END_G {
	$O = g;
}