title: Matlab, find nodes which are not participating in edges?
body: <p>In the following Matlab code, with nodes <code>N=10</code>, you will get randomly picked nodes with probability say <code>P= .25</code> marked as red nodes. </p>
  
  <pre><code>nodeN = [];
  nodeM = [];
  N=input('No. of Nodes:');
  P=input('probability of cluster head : ');
  R=input('range of cluster head: ')
  data = rand(N,2) % Randomly generated n no. of nodes
  x = data(:,1);
  y = data(:,2);
  plot(x,y,'b*')
  hold on
  index = (rand(N,1) &lt;= P);     %# to choose cluster head out of N nodes with probability P
  selected = data(index,:)   % nodes which are now cluster head 
  length(selected)           % no. of nodes which are cluster head
  not_selected  = data(~index,:) % remaining nodes which would be cluster members(out of N nodes)
  length(not_selected)           % no. of remaining nodes 
  plot(x(index),y(index),'r*');  % cluster head will be colored red in figure
  
  for i=1:length(selected);
  for j=1:length(not_selected);
  dist_ij = sqrt(sum((selected(i,:)- not_selected(j,:)).^2)) % distance between selected cluster heads and remaining nodes
  if(dist_ij&lt;=R) 
          nodeN = [nodeN; selected(i,:)]
      nodeM = [nodeM; not_selected(j,:)]
  end;
  end;
  end;
  
  if size(nodeN,1)~=0 &amp;&amp; size(nodeN,2)~=0 &amp;&amp; size(nodeM,1)~=0 &amp;&amp; size(nodeM,2)~=0
   X1=[nodeN(:,1)' ; nodeM(:,1)'] 
   Y1=[nodeN(:,2)' ; nodeM(:,2)'] 
  plot(X1,Y1)
  hold on
  end;
  </code></pre>
  
  <p>How do I find a matrix of those remaining blue colored nodes which are not in range and do not make any edge with red colored nodes and plot those nodes green?</p>