1function C = extract (arg1, arg2, arg3, arg4, arg5, arg6, arg7)
2%GRB.EXTRACT extract sparse submatrix.
3%
4%   C = GrB.extract (Cin, M, accum, A, I, J, desc)
5%
6%   C<M> = A(I,J) or accum (C, A(I,J))
7%
8% A is a required parameter.  All others are optional, but if M or accum
9% appears, then Cin is also required.  If desc.in0 is 'transpose', then
10% the description below assumes A = A' is computed first before the
11% extraction (A is not changed on output, however).
12%
13% desc: see 'help GrB.descriptorinfo' for details.
14%
15% I and J are cell arrays.  I contains 0, 1, 2, or 3 items:
16%
17%       0:   { }    This is the MATLAB ':', like A(:,J), refering to all m
18%                   rows, if A is m-by-n.
19%
20%       1:   { I }  1D list of row indices, like A(I,J) in MATLAB.
21%
22%       2:  { start,fini }  start and fini are scalars (either double,
23%                   int64, or uint64).  This defines I = start:fini in
24%                   MATLAB index notation.
25%
26%       3:  { start,inc,fini } start, inc, and fini are scalars (double,
27%                   int64, or uint64).  This defines I = start:inc:fini in
28%                   MATLAB notation.
29%
30%       The J argument is identical, except that it is a list of column
31%       indices of A.  If only one cell array is provided, J = {  } is
32%       implied, refering to all n columns of A, like A(I,:) in MATLAB
33%       notation.  1D indexing of a matrix A, as in C = A(I), is not yet
34%       supported.
35%
36%       If neither I nor J are provided on input, then this implies
37%       both I = { } and J = { }, or A(:,:) in MATLAB notation,
38%       refering to all rows and columns of A.
39%
40%       If desc.base is 'zero-based', then I and J are interpretted as
41%       zero-based, where the rows and columns of A range from 0 to m-1 and
42%       n-1, respectively.  If desc.base is 'one-based' (which is the
43%       default), then indices are intrepetted as 1-based, just as in MATLAB.
44%
45% Cin: an optional input matrix, containing the initial content of the
46%       matrix C.  C on output is the content of C after the assignment is
47%       made.  If present, Cin argument has size length(I)-by-length(J).
48%       If accum is present then Cin is a required input.
49%
50% accum: an optional binary operator, defined by a string ('+.double') for
51%       example.  This allows for C = Cin + A(I,J) to be computed.  If
52%       not present, no accumulator is used and C=A(I,J) is computed.
53%       If accum is present then Cin is a required input.
54%
55% M: an optional mask matrix, the same size as C.
56%
57% Example:
58%
59%   A = sprand (5, 4, 0.5)
60%   I = [2 1 5]
61%   J = [3 3 1 2]
62%   C = GrB.extract (A, {I}, {J})
63%   C2 = A (I,J)
64%   C2 - C
65%
66% See also GrB/subsref.
67
68% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2021, All Rights Reserved.
69% SPDX-License-Identifier: GPL-3.0-or-later
70
71if (isobject (arg1))
72    arg1 = arg1.opaque ;
73end
74
75if (nargin > 1 && isobject (arg2))
76    arg2 = arg2.opaque ;
77end
78
79if (nargin > 2 && isobject (arg3))
80    arg3 = arg3.opaque ;
81end
82
83if (nargin > 3 && isobject (arg4))
84    arg4 = arg4.opaque ;
85end
86
87if (nargin > 4 && isobject (arg5))
88    arg5 = arg5.opaque ;
89end
90
91if (nargin > 5 && isobject (arg6))
92    arg6 = arg6.opaque ;
93end
94
95switch (nargin)
96    case 1
97        [C, k] = gbextract (arg1) ;
98    case 2
99        [C, k] = gbextract (arg1, arg2) ;
100    case 3
101        [C, k] = gbextract (arg1, arg2, arg3) ;
102    case 4
103        [C, k] = gbextract (arg1, arg2, arg3, arg4) ;
104    case 5
105        [C, k] = gbextract (arg1, arg2, arg3, arg4, arg5) ;
106    case 6
107        [C, k] = gbextract (arg1, arg2, arg3, arg4, arg5, arg6) ;
108    case 7
109        [C, k] = gbextract (arg1, arg2, arg3, arg4, arg5, arg6, arg7) ;
110end
111
112if (k == 0)
113    C = GrB (C) ;
114end
115
116