comparison toolboxes/FullBNT-1.0.7/graph/mk_nbrs_of_digraph_broken.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function [Gs, op, nodes] = mk_nbrs_of_digraph(G0)
+% MK_NBRS_OF_DIGRAPH Make all digraphs that differ from G0 by a single edge deletion, addition or reversal
+% [Gs, op, nodes] = mk_nbrs_of_digraph(G0)
+%
+% Gs(:,:,i) is the i'th neighbor
+% op{i} = 'add', 'del', or 'rev' is the operation used to create the i'th neighbor. 
+% nodes(i,1:2) are the head and tail of the operated-on arc.
+
+debug = 0; % the vectorized version is about 3 to 10 times faster
+
+n = length(G0);
+[I,J] = find(G0); % I(k), J(k) is the k'th edge
+E = length(I); % num edges present in G0
+
+% SINGLE EDGE DELETIONS
+
+Grep = repmat(G0(:), 1, E); % each column is a copy of G0
+% edge_ndx(k) is the scalar location of the k'th edge 
+edge_ndx = find(G0);
+% edge_ndx = subv2ind([n n], [I J]); % equivalent
+% We set (ndx(k), k) to 0 for k=1:E in Grep
+ndx = subv2ind(size(Grep), [edge_ndx(:) (1:E)']);
+G1 = Grep;
+G1(ndx) = 0;
+Gdel = reshape(G1, [n n E]);
+
+
+% if debug
+% % Non-vectorized version
+% ctr = 1;
+% for e=1:E
+%   i = I(e); j = J(e);
+%   Gdel2(:,:,ctr) = G0;
+%   Gdel2(i,j,ctr) = 0;
+%   ctr = ctr + 1;
+% end
+% assert(isequal(Gdel, Gdel2));
+% end
+
+
+% SINGLE EDGE REVERSALS
+
+% rev_edge_ndx(k) is the scalar location of the k'th reversed edge
+%rev_edge_ndx = find(G0'); % different order to edge_ndx, which is bad
+rev_edge_ndx = subv2ind([n n], [J I]);
+% We set (rev_edge_ndx(k), k) to 1 for k=1:E in G1
+% We have already deleted i->j in the previous step
+ndx = subv2ind(size(Grep), [rev_edge_ndx(:) (1:E)']);
+G1(ndx) = 1;
+Grev = reshape(G1, [n n E]);
+
+% if debug
+% % Non-vectorized version
+% ctr = 1;
+% for e=1:E
+%   i = I(e); j = J(e);
+%   Grev2(:,:,ctr) = G0;
+%   Grev2(i,j,ctr) = 0;
+%   Grev2(j,i,ctr) = 1;
+%   ctr = ctr + 1;
+% end
+% assert(isequal(Grev, Grev2));
+% end
+
+
+% SINGLE EDGE ADDITIONS
+
+Gbar = ~G0; % Gbar(i,j)=1 iff there is no i->j edge in G0
+Gbar = setdiag(Gbar, 0); % turn off self loops
+[Ibar,Jbar] = find(Gbar); 
+
+bar_edge_ndx = find(Gbar);
+Ebar = length(Ibar); % num edges present in Gbar
+Grep = repmat(G0(:), 1, Ebar); % each column is a copy of G0
+ndx = subv2ind(size(Grep), [bar_edge_ndx(:) (1:Ebar)']);
+Grep(ndx) = 1;
+Gadd = reshape(Grep, [n n Ebar]);
+
+% if debug
+% % Non-vectorized version
+% ctr = 1;
+% for e=1:length(Ibar)
+%   i = Ibar(e); j = Jbar(e);
+%   Gadd2(:,:,ctr) = G0;
+%   Gadd2(i,j,ctr) = 1;
+%   ctr = ctr + 1;
+% end
+% assert(isequal(Gadd, Gadd2));
+% end
+
+
+Gs = cat(3, Gdel, Grev, Gadd);
+
+nodes = [I J;
+	 I J;
+	 Ibar Jbar];
+
+op = cell(1, E+E+Ebar);
+op(1:E) = {'del'};
+op(E+1:2*E) = {'rev'};
+op(2*E+1:end) = {'add'};
+
+
+% numeric output:
+% op(i) = 1, 2, or 3, if the i'th neighbor was created by adding, deleting or reversing an arc.
+
+ADD = 1;
+DEL = 2;
+REV = 3;
+
+%op = [repmat(DEL, 1, E) repmat(REV, 1, E) repmat(ADD, 1, Ebar)];