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function result = entries (A, varargin)
%GRB.ENTRIES count or query the entries of a matrix.
% An entry A(i,j) in a GraphBLAS matrix is one that is present in the
% data structure. Unlike a built-in sparse matrix, a GraphBLAS matrix can
% contain explicit zero entries. All entries in a built-in sparse matrix
% are nonzero. A built-in full matrix has all of its entries present,
% regardless of their value. The GrB.entries function looks only at the
% pattern of A, not its values. To exclude explicit entries with a value
% of zero (or any specified additive identity value) use GrB.nonz
% instead.
%
% Let [m n] = size (A)
%
% e = GrB.entries (A) number of entries
% e = GrB.entries (A, 'all') number of entries
% e = GrB.entries (A, 'row') number of rows with at least one entry
% e = GrB.entries (A, 'col') number of columns with at least one entry
%
% X = GrB.entries (A, 'list') list of values of unique entries
% X = GrB.entries (A, 'all', 'list') list of values of unique entries
% I = GrB.entries (A, 'row', 'list') list of rows with at least one entry
% J = GrB.entries (A, 'col', 'list') list of cols with at least one entry
%
% d = GrB.entries (A, 'row', 'degree')
% If A is m-by-n, then d is a sparse column vector of size m, with d(i)
% equal to the number of entries in A(i,:). If A(i,:) has no entries,
% then d(i) is an implicit zero, not present in the pattern of d, so
% that I = find (d) is the same I = GrB.entries (A, 'row', 'list').
%
% d = GrB.entries (A, 'col', 'degree')
% If A is m-by-n, d is a sparse column vector of size n, with d(j)
% equal to the number of entries in A(:,j). If A(:,j) has no entries,
% then d(j) is an implicit zero, not present in the pattern of d, so
% that I = find (d) is the same I = GrB.entries (A, 'col', 'list').
%
% The result is a built-in scalar or vector, except for the 'degree'
% usage, in which case the result is a GrB vector d.
%
% Example:
%
% A = magic (5) ;
% A (A < 10) = 0 % built-in full matrix with some explicit zeros
% GrB.entries (A) % all entries present in a built-in full matrix
% G = GrB (A) % contains explicit zeros
% GrB.entries (G)
% G (A > 18) = sparse (0) % entries A>18 deleted, has explicit zeros
% GrB.entries (G)
% GrB.entries (G, 'list')
% S = double (G) % built-in sparse matrix; no explicit zeros
% GrB.entries (S)
% GrB.entries (S, 'list')
%
% See also GrB.nonz, nnz, GrB/nnz, nonzeros, GrB/nonzeros.
% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0
if (isobject (A))
% A is a GraphBLAS matrix; get its opaque content
A = A.opaque ;
end
% get the count/list of the entries of A
result = gb_entries (A, varargin {:}) ;
% if gb_entries returned a GraphBLAS struct, return it as a GrB matrix
if (isstruct (result))
result = GrB (result) ;
end
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