Estimated Diameter
The diameter of a graph is the worstcase length of a shortest path between any pair of vertices in a graph. It is the farthest distance to travel, to get from one vertex to another, if you always take the shortest path. Finding the diameter requires calculating (the lengths of) all shortest paths, which can be quite slow.
This algorithm uses a simple heuristic to estimate the diameter. rather than calculating the distance from each vertex to every other vertex, it selects K vertices randomly, where K is a userprovided parameter. It calculates the distances from each of these K vertices to all other vertices. So, instead of calculating V*(V1) distances, this algorithm only calculates K*(V1) distances. The higher the value of K, the greater the likelihood of hitting the actual longest shortest path.
The current version only computes unweighted distances.
This algorithm query employs a subquery called max_BFS_depth. Both queries are needed to run the algorithm. 
Specifications
tg_estimate_diameter (SET<STRING> v_type, SET<STRING> e_type, INT seed_set_length,
BOOL print_accum = TRUE, STRING file_path = "", BOOL display = FALSE)
Characteristic  Value 

Result 
Returns the estimated value for the diameter of the graph 
Input Parameters 

Result Size 
one integer 
Time Complexity 
O(k*E), E = number of edges, k = number of seed vertices 
Graph Types 
Directed 