vl_ikmeans.c

Go to the documentation of this file.

/* file:        ikmeans.c
** description: MEX weighted ikmeans function.
** author:      Andrea Vedaldi
**/

/*
Copyright (C) 2014 Andrea Vedaldi.
Copyright (C) 2007-12 Andrea Vedaldi and Brian Fulkerson.
All rights reserved.

This file is part of the VLFeat library and is made available under
the terms of the BSD license (see the COPYING file).
*/

#include<mexutils.h>

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#include<assert.h>

#include <vl/ikmeans.h>
#include <vl/generic.h>

enum {
  opt_max_niters,
  opt_method,
  opt_verbose
} ;

vlmxOption  options [] = {
  {"MaxIters",     1,   opt_max_niters  },
  {"Method",       1,   opt_method      },
  {"Verbose",      0,   opt_verbose     },
  {0,              0,   0               }
} ;


/* driver */
void mexFunction (int nout, mxArray * out[], int nin, const mxArray * in[])
{
  enum {IN_X = 0, IN_K, IN_END} ;
  enum {OUT_C = 0, OUT_I} ;

  int opt ;
  int next = IN_END ;
  mxArray const  *optarg ;


  VlIKMFilt *ikmf ;
  vl_uint8 *data ;
  mwSize M, N, K ;
  int method_type = VL_IKM_LLOYD ;
  int max_niters  = 200 ;
  int verb = 0 ;
  int err = 0 ;

  VL_USE_MATLAB_ENV ;

  /* -----------------------------------------------------------------
   *                                               Check the arguments
   * -------------------------------------------------------------- */
  if (nin < 2) {
    mexErrMsgTxt ("At least two arguments required.");
  }
  else if (nout > 2) {
    mexErrMsgTxt ("Too many output arguments.");
  }
  if (mxGetClassID (in[IN_X]) != mxUINT8_CLASS) {
    mexErrMsgTxt ("X must be of class UINT8.");
  }

  M = mxGetM(in[IN_X]);   /* n of components */
  N = mxGetN(in[IN_X]);   /* n of elements */

  if (!vlmxIsPlainScalar (in[IN_K]) ||
      (K = (int) *mxGetPr(in[IN_K])) < 1 ||
      K > N) {
    mexErrMsgTxt ("K must be a positive integer not greater than the number of data.");
  }

  while ((opt = vlmxNextOption (in, nin, options, &next, &optarg)) >= 0) {
    char buf [1024] ;

    switch (opt) {

    case opt_verbose :
      ++ verb ;
      break ;

    case opt_max_niters :
      if (!vlmxIsPlainScalar(optarg) || (max_niters = (int) *mxGetPr(optarg)) < 1) {
        mexErrMsgTxt("MaxNIters must be not smaller than 1.") ;
      }
      break ;

    case opt_method :
      if (!vlmxIsString (optarg, -1)) {
        mexErrMsgTxt("'Method' must be a string.") ;
      }
      if (mxGetString (optarg, buf, sizeof(buf))) {
        mexErrMsgTxt("Option argument too long.") ;
      }
      if (strcmp("lloyd", buf) == 0) {
        method_type = VL_IKM_LLOYD ;
      } else if (strcmp("elkan", buf) == 0) {
        method_type = VL_IKM_ELKAN ;
      } else {
        mexErrMsgTxt("Unknown method type.") ;
      }
      break ;

    default :
      abort() ;
    }
  }

  /* -----------------------------------------------------------------
   *                                                        Do the job
   * -------------------------------------------------------------- */

  if (verb) {
    char const * method_name = 0 ;
    switch (method_type) {
    case VL_IKM_LLOYD: method_name = "Lloyd" ; break ;
    case VL_IKM_ELKAN: method_name = "Elkan" ; break ;
    default :
      abort() ;
    }
    mexPrintf("vl_ikmeans: MaxInters = %d\n", max_niters) ;
    mexPrintf("vl_ikmeans: Method = %s\n", method_name) ;
  }

  data = (vl_uint8*) mxGetData(in[IN_X]) ;
  ikmf = vl_ikm_new (method_type) ;

  vl_ikm_set_verbosity (ikmf, verb) ;
  vl_ikm_set_max_niters (ikmf, max_niters) ;
  vl_ikm_init_rand_data (ikmf, data, M, N, K) ;

  err = vl_ikm_train (ikmf, data, N) ;
  if (err) mexWarnMsgTxt("vl_ikmeans: possible overflow!") ;

  /* -----------------------------------------------------------------
 *                                                      Return results
   * -------------------------------------------------------------- */

  {
    out[OUT_C] = mxCreateNumericMatrix (M, K, mxINT32_CLASS, mxREAL) ;
    memcpy(mxGetData(OUT(C)),
           vl_ikm_get_centers(ikmf),
           sizeof(vl_ikmacc_t) * M * K) ;
  }

  if (nout > 1) {
    vl_uindex i ;
    vl_uint32 *asgn  ;
    out[OUT_I] = mxCreateNumericMatrix (1, N, mxUINT32_CLASS, mxREAL) ;
    asgn = (vl_uint32*) mxGetData (out[OUT_I]) ;

    vl_ikm_push (ikmf, asgn, data, N) ;

    for (i = 0 ; i < N ; ++i) { ++ asgn [i] ; }
  }

  vl_ikm_delete (ikmf) ;

  if (verb) {
    mexPrintf("vl_ikmeans: done\n") ;
  }
}