int main (int argc, char **argv)
{
//--------------------------------------------------------------------------
// initializations
//--------------------------------------------------------------------------
GrB_Info info ;
GrB_Matrix A = NULL ;
PageRank *Pd = NULL, *P2 = NULL ;
iPageRank *Pi = NULL ;
double tic [2], t ;
OK (GrB_init (GrB_NONBLOCKING)) ;
fprintf (stderr, "\npagerank_demo:\n") ;
printf ( "\npagerank_demo:\n") ;
//--------------------------------------------------------------------------
// read a matrix from stdin
//--------------------------------------------------------------------------
bool one_based = false ;
if (argc > 1) one_based = strtol (argv [1], NULL, 0) ;
OK (read_matrix (&A,
stdin, // read matrix from stdin
false, // unsymmetric
false, // self edges OK
one_based, // 0-based or 1-based, depending on input arg
true, // read input file as Boolean
true)) ; // print status to stdout
GrB_Index n, nvals ;
OK (GrB_Matrix_nrows (&n, A)) ;
OK (GrB_Matrix_nvals (&nvals, A)) ;
//--------------------------------------------------------------------------
// compute the page rank via a real semiring
//--------------------------------------------------------------------------
simple_tic (tic) ;
OK (dpagerank (&Pd, A)) ;
t = simple_toc (tic) ;
fprintf (stderr, "n %g edges %g dpagerank time : %14.6f iters: 20\n",
(double) n, (double) nvals, t) ;
printf ( "n %g edges %g dpagerank time : %14.6f iters: 20\n",
(double) n, (double) nvals, t) ;
//--------------------------------------------------------------------------
// compute the page rank via an integer semiring
//--------------------------------------------------------------------------
simple_tic (tic) ;
OK (ipagerank (&Pi, A)) ;
t = simple_toc (tic) ;
fprintf (stderr, "n %g edges %g ipagerank time : %14.6f iters: 20\n",
(double) n, (double) nvals, t) ;
printf ( "n %g edges %g ipagerank time : %14.6f iters: 20\n",
(double) n, (double) nvals, t) ;
//--------------------------------------------------------------------------
// compute the page rank via an extreme semiring
//--------------------------------------------------------------------------
int iters ;
simple_tic (tic) ;
OK (dpagerank2 (&P2, A, 100, 1e-5, &iters, GxB_DEFAULT)) ;
t = simple_toc (tic) ;
fprintf (stderr, "n %g edges %g dpagerank time : %14.6f iters: %d\n",
(double) n, (double) nvals, t, iters) ;
printf ( "n %g edges %g dpagerank time : %14.6f iters: %d\n",
(double) n, (double) nvals, t, iters) ;
//--------------------------------------------------------------------------
// print results
//--------------------------------------------------------------------------
int64_t limit = MIN (n, 5000) ;
printf ("Top %g nodes:\n", (double) limit) ;
for (int64_t i = 0 ; i < limit ; i++)
{
printf ("%5g d:[%6g : %16.8e] i:[%6g : %16.8e] x:[%6g : %16.8e]",
(double) i,
(double) Pd [i].page, (double) Pd [i].pagerank,
(double) Pi [i].page, (double) Pi [i].pagerank,
(double) P2 [i].page, (double) P2 [i].pagerank) ;
if (Pd [i].page != Pi [i].page || Pd [i].page != P2 [i].page)
{
printf ("mismatch") ;
}
printf ("\n") ;
}
//--------------------------------------------------------------------------
// free all workspace
//--------------------------------------------------------------------------
FREE_ALL ;
GrB_finalize ( ) ;
}
GrB_Info ktruss_graphblas // compute the k-truss of a graph
(
GrB_Matrix *p_C, // output k-truss subgraph, C
GrB_Matrix A, // input adjacency matrix, A, not modified
const int64_t k, // find the k-truss, where k >= 3
int64_t *p_nsteps // # of steps taken
)
{
//--------------------------------------------------------------------------
// check inputs
//--------------------------------------------------------------------------
// ensure k is 3 or more
if (k < 3) return (GrB_INVALID_VALUE) ;
if (p_C == NULL || p_nsteps == NULL) return (GrB_NULL_POINTER) ;
//--------------------------------------------------------------------------
// initializations
//--------------------------------------------------------------------------
GrB_Info info ;
GxB_SelectOp supportop = NULL ;
GrB_Index n ;
GrB_Matrix C = NULL ;
OK (GrB_Matrix_nrows (&n, A)) ;
OK (GrB_Matrix_new (&C, GrB_INT64, n, n)) ;
// select operator
int64_t support = (k-2) ;
OK (GxB_SelectOp_new (&supportop, support_function, GrB_INT64)) ;
// last_cnz = nnz (A)
GrB_Index cnz, last_cnz ;
OK (GrB_Matrix_nvals (&last_cnz, A)) ;
//--------------------------------------------------------------------------
// find the k-truss of A
//--------------------------------------------------------------------------
double tmult = 0 ;
double tsel = 0 ;
for (int64_t nsteps = 1 ; ; nsteps++)
{
//----------------------------------------------------------------------
// C<C> = C*C
//----------------------------------------------------------------------
GrB_Matrix Cin = (nsteps == 1) ? A : C ;
double t1 = omp_get_wtime ( ) ;
OK (GrB_mxm (C, Cin, NULL, GxB_PLUS_LAND_INT64, Cin, Cin, NULL)) ;
double t2 = omp_get_wtime ( ) ;
printf ("C<C>=C*C time: %g\n", t2-t1) ;
tmult += (t2-t1) ;
//----------------------------------------------------------------------
// C = C .* (C >= support)
//----------------------------------------------------------------------
OK (GxB_select (C, NULL, NULL, supportop, C, &support, NULL)) ;
double t3 = omp_get_wtime ( ) ;
printf ("select time: %g\n", t3-t2) ;
tsel += (t3-t2) ;
//----------------------------------------------------------------------
// check if the k-truss has been found
//----------------------------------------------------------------------
OK (GrB_Matrix_nvals (&cnz, C)) ;
if (cnz == last_cnz)
{
printf ("ktruss_grb done: tmult %g tsel %g\n", tmult, tsel) ;
(*p_C) = C ; // return the output matrix C
(*p_nsteps) = nsteps ; // return # of steps
OK (GrB_free (&supportop)) ; // free the select operator
return (GrB_SUCCESS) ;
}
last_cnz = cnz ;
}
}
