Documentation>vl_demo_kmeans_vs_builtin

# Source code for ``vl_demo_kmeans_vs_builtin.m

This file is located in the ``toolbox/demo folder in VLFeat package.

    % VL_DEMO_KMEANS_VS_BUILTIN

    clear elaps energy ;

    dimension  = 128 ;
    numData    = 1000 ;
    numCenters = 10 ;
    numTrials  = 10 ;

    for trial = 1:numTrials
      X = rand(dimension, numData) ;

      tic ;
      [idx, C, e] = kmeans(X', numCenters) ;
      e = sum(e) ;
      elaps.builtin(trial) = toc ;
      energy.builtin(trial) = e ;

      tic ;
      [idx_, C_, e] = vl_kmeans(X, numCenters, 'verbose') ;
      elaps.vl(trial) = toc ;
      energy.vl(trial) = e ;

      tic ;
      [idx_, C_, e] = vl_kmeans(X, numCenters, 'initialization', 'plusplus') ;
      elaps.vlpp(trial) = toc ;
      energy.vlpp(trial) = e ;
    end

    figure(1) ; clf ;
    subplot(1,2,1) ; title('Energy') ;
    mu = [mean(elaps.builtin) mean(elaps.vl) mean(elaps.vlpp)] ;
    st = [std(elaps.builtin) std(elaps.vl) std(elaps.vlpp)] ;
    bar(mu) ; hold on ;
    errorbar(mu, st, 'linestyle', 'none', 'color', 'r', 'linewidth', 4) ;

    subplot(1,2,2) ;
    mu = [mean(energy.builtin) mean(energy.vl) mean(energy.vlpp)] ;
    st = [std(energy.builtin) std(energy.vl) std(energy.vlpp)] ;
    bar(mu) ; hold on ;
    errorbar(mu, st, 'linestyle', 'none', 'color', 'r', 'linewidth', 4) ;