Once a graph topology is set up, it may be necessary to inquire about the topology. These functions are given below and are all local calls.
MPI_Graphdims_get(MPI_Comm comm, int *nnodes, int *nedges)
MPI_GRAPHDIMS_GET(COMM, NNODES, NEDGES, IERROR)INTEGER COMM, NNODES, NEDGES, IERROR
MPI_GRAPHDIMS_GET returns the number of nodes
and the number of edges in the graph. The number of nodes is
identical to the size of the group associated with comm.
nnodes and nedges can be used to supply arrays of
correct size for index and edges, respectively, in
MPI_GRAPH_GET. MPI_GRAPHDIMS_GET would return
nnodes = 4 and nedges = 6for
Example 
.
MPI_Graph_get(MPI_Comm comm, int maxindex, int maxedges, int *index, int *edges)
MPI_GRAPH_GET(COMM, MAXINDEX, MAXEDGES, INDEX, EDGES, IERROR)INTEGER COMM, MAXINDEX, MAXEDGES, INDEX(*), EDGES(*), IERROR
MPI_GRAPH_GET returns index and edges as
was supplied to MPI_GRAPH_CREATE. maxindex and
maxedges are at least as big as nnodes and
nedges, respectively, as returned by
MPI_GRAPHDIMS_GET above. Using the comm created
in Example would return the index and
edges given in the example.