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//------------------------------------------------------------------------------
// GxB_Col_extract_Vector: w<M> = accum (w, A(I,j)) or A(j,I)'
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2025, All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//------------------------------------------------------------------------------
// Extract a single row or column from a matrix. Note that in the
// GraphBLAS spec, row and column vectors are indistinguishable. In this
// implementation, both are the same as an n-by-1 GrB_Matrix, except with
// restrictions on the matrix operations that can be performed on them.
#include "extract/GB_extract.h"
#include "mask/GB_get_mask.h"
#include "ij/GB_ij.h"
#define GB_FREE_ALL \
if (I_size > 0) GB_FREE_MEMORY (&I, I_size) ;
GrB_Info GxB_Col_extract_Vector // w<mask> = accum (w, A(I,j))
(
GrB_Vector w, // input/output matrix for results
const GrB_Vector mask, // optional mask for w, unused if NULL
const GrB_BinaryOp accum, // optional accum for z=accum(w,t)
const GrB_Matrix A, // first input: matrix A
const GrB_Vector I_vector, // row indices
uint64_t j, // column index
const GrB_Descriptor desc // descriptor for w, mask, and A
)
{
//--------------------------------------------------------------------------
// check inputs
//--------------------------------------------------------------------------
GB_RETURN_IF_NULL (w) ;
GB_RETURN_IF_NULL (A) ;
GB_RETURN_IF_OUTPUT_IS_READONLY (w) ;
GB_WHERE4 (w, mask, A, I_vector,
"GxB_Col_extract_Vector (w, M, accum, A, I, j, desc)") ;
GB_BURBLE_START ("GrB_extract") ;
ASSERT (GB_VECTOR_OK (w)) ;
ASSERT (GB_IMPLIES (mask != NULL, GB_VECTOR_OK (mask))) ;
// get the descriptor
GB_GET_DESCRIPTOR (info, desc, C_replace, Mask_comp, Mask_struct,
A_transpose, xx1, xx2, xx7) ;
// get the mask
GrB_Matrix M = GB_get_mask ((GrB_Matrix) mask, &Mask_comp, &Mask_struct) ;
uint64_t ancols = (A_transpose ? GB_NROWS (A) : GB_NCOLS (A)) ;
if (j >= ancols)
{
GB_ERROR (GrB_INVALID_INDEX,
"Column index j=" GBu " out of bounds; must be < " GBu ,
j, ancols) ;
}
//--------------------------------------------------------------------------
// get the index vector
//--------------------------------------------------------------------------
void *I = NULL ;
size_t I_size = 0 ;
int64_t ni = 0 ;
GrB_Type I_type = NULL ;
GB_OK (GB_ijxvector (I_vector, (w == I_vector), 0, desc, false,
&I, &ni, &I_size, &I_type, Werk)) ;
bool I_is_32 = (I_type == GrB_UINT32) ;
//--------------------------------------------------------------------------
// extract the jth column (or jth row if A is transposed) using GB_extract
//--------------------------------------------------------------------------
// construct the column index list J = [ j ] of length nj = 1
uint64_t J [1] ;
J [0] = j ;
//--------------------------------------------------------------------------
// do the work in GB_extract
//--------------------------------------------------------------------------
GB_OK (GB_extract (
(GrB_Matrix) w, C_replace, // w as a matrix, and descriptor
M, Mask_comp, Mask_struct, // mask and its descriptor
accum, // optional accum for z=accum(w,t)
A, A_transpose, // A and its descriptor
I, I_is_32, ni, // row indices
J, false, 1, // one column index, nj = 1 (64-bit)
Werk)) ;
//--------------------------------------------------------------------------
// free workspace and return result
//--------------------------------------------------------------------------
GB_FREE_ALL ;
GB_BURBLE_END ;
return (GrB_SUCCESS) ;
}
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