1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
function result = nonz (A, varargin)
%GRB.NONZ count or query the nonzeros of a matrix.
% A GraphBLAS matrix can include explicit entries that have the value
% zero. These entries never appear in a built-in sparse matrix. This
% function counts or queries the nonzeros of matrix, checking their value
% and treating explicit zeros the same as entries that do not appear in
% the pattern of A.
%
% e = GrB.nonz (A) number of nonzeros
% e = GrB.nonz (A, 'all') number of nonzeros
% e = GrB.nonz (A, 'row') number of rows with at least one nonzero
% e = GrB.nonz (A, 'col') number of columns with at least one nonzero
%
% X = GrB.nonz (A, 'list') list of values of unique nonzeros
% X = GrB.nonz (A, 'all', 'list') list of values of unique nonzeros
% I = GrB.nonz (A, 'row', 'list') list of rows with at least one nonzero
% J = GrB.nonz (A, 'col', 'list') list of cols with at least one nonzero
%
% d = GrB.nonz (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 nonzeros in A(i,:). If A(i,:) has no
% nonzeros, then d(i) is an implicit zero, not present in the pattern
% of d, so I = find (d) is the same I = GrB.nonz (A, 'row', 'list').
%
% d = GrB.nonz (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 nonzeros in A(:,j). If A(:,j) has no
% nonzeros, then d(j) is an implicit zero, not present in the pattern
% of d, so I = find (d) is the same I = GrB.nonz (A, 'col', 'list').
%
% With an optional scalar argument as the last argument, the value of the
% 'zero' can be specified; d = GrB.nonz (A, ..., id). For example, to
% count all entries in A not equal to one, use GrB.nonz (A, 1).
%
% 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 explicit zeros
% nnz (A)
% GrB.nonz (A) % same as nnz (A)
% G = GrB (A) % contains explicit zeros
% GrB.nonz (G) % same as nnz (A)
% G (A > 18) = sparse (0) % entries A>18 deleted, explicit zeros
% GrB.nonz (G)
% GrB.nonz (G, 'list')
% S = double (G) % built-in sparse matrix; no explicit zeros
% GrB.nonz (S)
% GrB.nonz (S, 'list')
%
% See also GrB.entries, GrB/nnz, GrB/nonzeros, GrB.prune.
% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0
builtin_sparse = false ;
if (isobject (A))
% A is a GraphBLAS matrix; get its opaque content
A = A.opaque ;
elseif (builtin ('issparse', A))
% A is a built-in sparse matrix
builtin_sparse = true ;
end
% get the identity value
id = 0 ;
nargs = nargin ;
if (nargin > 1)
lastarg = varargin {nargs-1} ;
if (~ischar (lastarg))
% the last argument is id, if it is not a string
id = gb_get_scalar (lastarg) ;
nargs = nargs - 1 ;
end
end
if (id ~= 0)
% id is nonzero, so prune A first (for any matrix A)
A = gbselect (A, '~=', id) ;
elseif (~builtin_sparse)
% id is zero, so prune A only if it is a GraphBLAS matrix,
% or a built-in full matrix. A built-in sparse matrix can remain
% unchanged.
A = gbselect (A, 'nonzero') ;
end
% get the count/list of the entries of A
result = gb_entries (A, varargin {1:nargs-1}) ;
% if gb_entries returned a GraphBLAS struct, return it as a GrB matrix
if (isstruct (result))
result = GrB (result) ;
end
|
