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//------------------------------------------------------------------------------
// LAGraph_Cached_InDegree: determine G->in_degree
//------------------------------------------------------------------------------
// LAGraph, (c) 2019-2022 by The LAGraph Contributors, All Rights Reserved.
// SPDX-License-Identifier: BSD-2-Clause
//
// For additional details (including references to third party source code and
// other files) see the LICENSE file or contact permission@sei.cmu.edu. See
// Contributors.txt for a full list of contributors. Created, in part, with
// funding and support from the U.S. Government (see Acknowledgments.txt file).
// DM22-0790
// Contributed by Timothy A. Davis, Texas A&M University
//------------------------------------------------------------------------------
// LAGraph_Cached_InDegree computes G->in_degree, where G->in_degree(j) is
// the number of entries in G->A (:,j). If there are no entries in G->A (:,j),
// G->coldgree(j) is not present in the structure of G->in_degree. That is,
// G->in_degree contains no explicit zero entries.
// G->in_degree is not computed if the graph is undirected. Use G->out_degree
// instead, and LAGraph_Cached_OutDegree.
#define LG_FREE_WORK \
{ \
GrB_free (&S) ; \
GrB_free (&x) ; \
}
#define LG_FREE_ALL \
{ \
LG_FREE_WORK ; \
GrB_free (&in_degree) ; \
}
#include "LG_internal.h"
int LAGraph_Cached_InDegree
(
// input/output:
LAGraph_Graph G, // graph to determine G->in_degree
char *msg
)
{
//--------------------------------------------------------------------------
// clear msg and check G
//--------------------------------------------------------------------------
GrB_Matrix S = NULL ;
GrB_Vector in_degree = NULL, x = NULL ;
LG_CLEAR_MSG_AND_BASIC_ASSERT (G, msg) ;
if (G->in_degree != NULL)
{
// G->in_degree already computed
return (GrB_SUCCESS) ;
}
if (G->kind == LAGraph_ADJACENCY_UNDIRECTED)
{
// G->in_degree is not computed since A is symmetric (warning only)
return (LAGRAPH_CACHE_NOT_NEEDED) ;
}
//--------------------------------------------------------------------------
// determine the size of A
//--------------------------------------------------------------------------
GrB_Matrix A = G->A ;
GrB_Matrix AT = G->AT ;
GrB_Index nrows, ncols ;
GRB_TRY (GrB_Matrix_nrows (&nrows, A)) ;
GRB_TRY (GrB_Matrix_ncols (&ncols, A)) ;
//--------------------------------------------------------------------------
// compute the in_degree
//--------------------------------------------------------------------------
GRB_TRY (GrB_Vector_new (&in_degree, GrB_INT64, ncols)) ;
// x = zeros (nrows,1)
GRB_TRY (GrB_Vector_new (&x, GrB_INT64, nrows)) ;
GRB_TRY (GrB_assign (x, NULL, NULL, 0, GrB_ALL, nrows, NULL)) ;
if (AT != NULL)
{
// G->in_degree = row degree of AT; this will be faster assuming
// AT is held in a row-oriented format.
GRB_TRY (GrB_mxv (in_degree, NULL, NULL, LAGraph_plus_one_int64,
AT, x, NULL)) ;
}
else
{
// G->in_degree = column degree of A
GRB_TRY (GrB_mxv (in_degree, NULL, NULL, LAGraph_plus_one_int64,
A, x, GrB_DESC_T0)) ;
}
G->in_degree = in_degree ;
LG_FREE_WORK ;
return (GrB_SUCCESS) ;
}