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//------------------------------------------------------------------------------
// LAGraph_DeleteSelfEdges: removes the diagonal entries from G->A
//------------------------------------------------------------------------------
// 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
//------------------------------------------------------------------------------
#include "LG_internal.h"
int LAGraph_DeleteSelfEdges
(
// input/output:
LAGraph_Graph G, // diagonal entries removed, most cached properties cleared
char *msg
)
{
//--------------------------------------------------------------------------
// clear msg and check G
//--------------------------------------------------------------------------
LG_CLEAR_MSG_AND_BASIC_ASSERT (G, msg) ;
if (G->nself_edges == 0)
{
// nothing to do
return (GrB_SUCCESS) ;
}
//--------------------------------------------------------------------------
// delete all cached properties not affected by the removal of the diagonal
//--------------------------------------------------------------------------
LAGraph_Boolean is_symmetric_structure = G->is_symmetric_structure ;
LG_TRY (LAGraph_DeleteCached (G, msg)) ;
G->is_symmetric_structure = is_symmetric_structure ;
//--------------------------------------------------------------------------
// remove diagonal entries
//--------------------------------------------------------------------------
GRB_TRY (GrB_select (G->A, NULL, NULL, GrB_OFFDIAG, G->A, 0, NULL)) ;
//--------------------------------------------------------------------------
// free workspace, G->nself_edges now known to be zero
//--------------------------------------------------------------------------
G->nself_edges = 0 ;
return (GrB_SUCCESS) ;
}