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//------------------------------------------------------------------------------
// GraphBLAS/Demo/Program/pagerank_demo.c: PageRank via various semirings
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2020, All Rights Reserved.
// http://suitesparse.com See GraphBLAS/Doc/License.txt for license.
//------------------------------------------------------------------------------
// Read a graph from a file and compute the pagerank of its nodes, using
// dpagerank and ipagerank.
// usage: ./pagerank_demo < file
// ./pagerank_demo 0 < file
// ./pagerank_demo 1 < file
//
// default is 0-based, for the matrices in the Matrix/ folder
//
// The infile has one line per edge in the graph; these have the form
//
// i j x
//
// where A(i,j)=x is performed by GrB_Matrix_build, to construct the matrix.
// The dimensions of A are assumed to be the largest row and column indices,
// plus one (in read_matrix.c).
//
// A must be square.
// macro used by OK(...) to free workspace if an error occurs
#define FREE_ALL \
{ \
GrB_Matrix_free (&A) ; \
if (Pd != NULL) free (Pd) ; \
if (Pi != NULL) free (Pi) ; \
if (P2 != NULL) free (P2) ; \
}
#include "graphblas_demos.h"
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)) ;
int nthreads ;
OK (GxB_Global_Option_get (GxB_GLOBAL_NTHREADS, &nthreads)) ;
fprintf (stderr, "\npagerank_demo: nthreads: %d\n", nthreads) ;
printf ( "\npagerank_demo: nthreads: %d\n", nthreads) ;
//--------------------------------------------------------------------------
// 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 ( ) ;
}
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