distmatrix_show

PURPOSE ^

Useful visualization of a distance matrix of clustered points.

SYNOPSIS ^

function distmatrix_show( D, IDX )

DESCRIPTION ^

 Useful visualization of a distance matrix of clustered points.

 D is sorted into k blocks, where the ith block contains all the points in cluster i.
 When D is displayed the blocks are shown explicitly.  Hence for a good clustering (under
 a spherical gaussian assumption) the 'diagnol' blocks ought to be mostly dark, and all
 other block ought to be relatively white.  One can thus quickly visualize the quality of
 the clustering, or even how clusterable the points are.  Outliers (according to IDX) are
 removed from D.

 INPUTS
   D       - nxn distance matrix
   IDX     - cluster membership [see kmeans2.m]
   
 OUTPUTS
   NONE

 EXAMPLE
  % not the best example since points are already ordered
  [X,IDX_true] = demogendata(100,0,2,2,10,2,0);  
  distmatrix_show( dist_euclidean(X,X), IDX_true );

 DATESTAMP
   29-Sep-2005  2:00pm

CROSS-REFERENCE INFORMATION ^

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