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function DiGraph = digraph (G, option)
%DIGRAPH convert a GraphBLAS matrix into a directed DiGraph.
% DiGraph = digraph (G) converts a GraphBLAS matrix G into a directed
% DiGraph. G must be square. If G is logical, then no weights are added
% to the DiGraph. If G is single or double, these become the weights of
% the DiGraph. If G is integer, the DiGraph is constructed with weights
% of type double.
%
% DiGraph = digraph (G, 'omitselfloops') ignores the diagonal of G, and
% the resulting DiGraph has no self-edges. The default is that
% self-edges are created from any diagonal entries of G.
%
% Example:
%
% G = GrB (sprand (8, 8, 0.2))
% DiGraph = digraph (G)
% h = plot (DiGraph) ;
% h.NodeFontSize = 20 ;
% h.ArrowSize = 20 ;
% h.LineWidth = 2 ;
% h.EdgeColor = [0 0 1] ;
% t = title ('random directed graph with 8 nodes') ;
% t.FontSize = 20 ;
%
% See also graph, digraph, GrB/graph.
% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0
G = G.opaque ;
[m, n, type] = gbsize (G) ;
if (m ~= n)
error ('GrB:error', 'G must be square') ;
end
% get the string options
omitself = false ;
if (nargin > 1)
if (isequal (lower (option), 'omitselfloops'))
omitself = true ;
else
error ('GrB:error', 'unknown option') ;
end
end
% apply the options
if (omitself)
% ignore diagonal entries of G
G = gbselect ('offdiag', G, 0) ;
end
% construct the digraph
switch (type)
case { 'single' }
% The digraph(...) function can accept x as single, but not
% from a sparse matrix. So extract the tuples of G first.
[i, j, x] = gbextracttuples (G) ;
DiGraph = digraph (i, j, x, n) ;
case { 'logical' }
% The digraph(...) function allows for logical
% adjacency matrices (no edge weights are created).
DiGraph = digraph (gbbuiltin (G, 'logical')) ;
otherwise
% typecast to double
DiGraph = digraph (gbbuiltin (G, 'double')) ;
end
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