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function [C,P] = GB_spec_Vector_sort (op, A, descriptor)
%GB_SPEC_MATRIX_SORT a mimic of GxB_Vector_sort
%
% Usage:
% [C,P] = GB_spec_Vector_sort (op, A, descriptor)
% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0
%-------------------------------------------------------------------------------
% get inputs
%-------------------------------------------------------------------------------
if (nargout > 2 || nargin ~= 3)
error ('usage: [C,P] = GB_spec_Vector_sort (op, A, descriptor)') ;
end
A = GB_spec_matrix (A) ;
[opname, optype, ztype, xtype, ytype] = GB_spec_operator (op, A.class) ;
[~, ~, Atrans, ~, ~] = GB_spec_descriptor (descriptor) ;
if (isequal (opname, 'lt'))
direction = 'ascend' ;
elseif (isequal (opname, 'gt'))
direction = 'descend' ;
else
error ('unknown order') ;
end
%-------------------------------------------------------------------------------
% do the work via a clean *.m interpretation of the entire GraphBLAS spec
%-------------------------------------------------------------------------------
% create C and P
[m,n] = size (A.matrix) ;
if (n ~= 1)
error ('A must be a vector') ;
end
C.matrix = zeros (m, n, A.class) ;
C.pattern = false (m, n) ;
C.class = A.class ;
P.matrix = zeros (m, n, 'int64') ;
P.pattern = false (m, n) ;
P.class = 'int64' ;
% sort the vector A; ignore implicit zeros
for j = 1:n
indices = find (A.pattern (:,j)) ;
values = A.matrix (indices, j) ;
T = sortrows ([values indices], { direction, 'ascend'} ) ;
nvals = length (indices) ;
C.matrix (1:nvals, j) = T (:,1) ; C.pattern (1:nvals, j) = true ;
P.matrix (1:nvals, j) = T (:,2) - 1 ; P.pattern (1:nvals, j) = true ;
end
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