comparison toolboxes/MIRtoolbox1.3.2/somtoolbox/som_neighbors.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function Ne = som_neighbors(sM,neigh)
+
+% Ne = som_neighbors(sM,neigh)
+%
+% sM      (struct) map or data struct
+%         (matrix) data matrix, size n x dim
+% [neigh] (string) 'kNN' or 'Nk' (which is valid for a SOM only)
+%                  for example '6NN' or 'N1'
+%                  default is '10NN' for a data set and 'N1' for SOM
+%
+% Ne      (matrix) size n x n, a sparse matrix
+%                  indicating the neighbors of each sample by value 1 
+%                  (note: the unit itself also has value 0)
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+if isstruct(sM), 
+  switch sM.type, 
+   case 'som_map',  M = sM.codebook; 
+   case 'som_data', M = sM.data; sM = []; 
+  end
+else
+  M = sM; 
+  sM = []; 
+end
+
+n = size(M,1);
+
+if nargin<2, 
+  if isempty(sM), neigh = '10NN'; else neigh = 'N1'; end
+end
+
+if strcmp(neigh(end-1:end),'NN'),
+  k  = str2num(neigh(1:end-2));
+  kmus = som_bmus(M,M,1:k+1);
+  Ne = sparse(n,n);
+  for i=1:n, Ne(i,kmus(i,:)) = 1; end
+else
+  if ~isstruct(sM), error('Prototypes must be in a map struct.'); end      
+  k  = str2num(neigh(2:end));
+  N1 = som_unit_neighs(sM);    
+  Ne = sparse(som_neighborhood(N1,k)<=k);
+end
+Ne([0:n-1]*n+[1:n]) = 0; % remove self from neighbors
+
+return;