grRemoveNodes

GRREMOVENODES Remove several nodes in a graph.

   usage:
   [NODES2 EDGES2] = grRemoveNodes(NODES, EDGES, NODES2REMOVE)
   remove the nodes with indices NODE2REMOVE from array NODES, and also
   remove edges containing the nodes NODE2REMOVE.

   Example
     nodes = [...
         10 10; 20 10; 30 10; ...
         10 20; 20 20; 30 20];
     edges = [...
         1 2; 1 4; 1 5; ...
         2 3; 2 5; 2 6; ...
         3 6; 4 5; 5 6];
     toRemove = [3 4];
     [nodes2 edges2] = grRemoveNodes(nodes, edges, toRemove);
     drawGraph(nodes2, edges2);
     axis equal; axis([0 40 0 30]);

   See also
     grRemoveEdges

0001 function [nodes2, edges2] = grRemoveNodes(nodes, edges, rmNodes)
0002 %GRREMOVENODES Remove several nodes in a graph.
0003 %
0004 %   usage:
0005 %   [NODES2 EDGES2] = grRemoveNodes(NODES, EDGES, NODES2REMOVE)
0006 %   remove the nodes with indices NODE2REMOVE from array NODES, and also
0007 %   remove edges containing the nodes NODE2REMOVE.
0008 %
0009 %   Example
0010 %     nodes = [...
0011 %         10 10; 20 10; 30 10; ...
0012 %         10 20; 20 20; 30 20];
0013 %     edges = [...
0014 %         1 2; 1 4; 1 5; ...
0015 %         2 3; 2 5; 2 6; ...
0016 %         3 6; 4 5; 5 6];
0017 %     toRemove = [3 4];
0018 %     [nodes2 edges2] = grRemoveNodes(nodes, edges, toRemove);
0019 %     drawGraph(nodes2, edges2);
0020 %     axis equal; axis([0 40 0 30]);
0021 %
0022 %   See also
0023 %     grRemoveEdges
0024 %
0025 
0026 % ------
0027 % Author: David Legland
0028 % E-mail: david.legland@inrae.fr
0029 % Created: 2003-08-13
0030 % Copyright 2003-2024 INRA - TPV URPOI - BIA IMASTE
0031 
0032 %% edges processing
0033 
0034 % remove all edges connected to one of the nodes to remove
0035 edges2 = edges(~any(ismember(edges, rmNodes), 2), :);
0036 
0037 % change edges information, due to the node index shift
0038 for i = 1:length(rmNodes)
0039     inds = edges2 > (rmNodes(i) - i + 1);
0040     edges2(inds) = edges2(inds) - 1;
0041 end
0042 
0043 
0044 %% nodes processing
0045 
0046 % number of nodes
0047 N   = size(nodes, 1);
0048 NR  = length(rmNodes);
0049 N2  = N-NR;
0050 
0051 % allocate memory
0052 nodes2 = zeros(N2, 2);
0053 
0054 % process the first node
0055 nodes2(1:rmNodes(1)-1,:) = nodes(1:rmNodes(1)-1,:);
0056 
0057 for i = 2:NR
0058     inds = rmNodes(i-1)+1:rmNodes(i)-1;
0059     if isempty(inds)
0060         continue;
0061     end
0062     nodes2(inds - i + 1, :) = nodes(inds, :);
0063 end
0064 
0065 % process the last node
0066 nodes2(rmNodes(NR)-NR+1:N2, :) = nodes(rmNodes(NR)+1:N, :);