NAG Library Manual, Mark 28.4
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_mv_cluster_kmeans (g03efc) Example Program.
 *
 * Copyright 2022 Numerical Algorithms Group.
 *
 * Mark 28.4, 2022.
 *
 */

#include <nag.h>
#include <stdio.h>

#define CMEANS(I, J) cmeans[(I)*tdcmeans + J]
#define X(I, J) x[(I)*tdx + J]
int main(void) {
  Integer exit_status = 0, i, *inc = 0, *isx = 0, j, k, m, maxit, n, *nic = 0,
          nvar;
  Integer tdcmeans, tdx;
  NagError fail;
  char weight[2];
  double *cmeans = 0, *css = 0, *csw = 0, *wt = 0, *wtptr, *x = 0;

  INIT_FAIL(fail);

  printf("nag_mv_cluster_kmeans (g03efc) Example Program Results"
         "\n\n");

  /* Skip heading in the data file */
  scanf("%*[^\n]");
  scanf("%1s", weight);
  scanf("%" NAG_IFMT "", &n);
  scanf("%" NAG_IFMT "", &m);
  scanf("%" NAG_IFMT "", &nvar);
  scanf("%" NAG_IFMT "", &k);
  scanf("%" NAG_IFMT "", &maxit);

  if (n >= 2 && nvar >= 1 && m >= nvar && k >= 2) {
    if (!(cmeans = NAG_ALLOC((k) * (nvar), double)) ||
        !(css = NAG_ALLOC(k, double)) || !(csw = NAG_ALLOC(k, double)) ||
        !(wt = NAG_ALLOC(n, double)) || !(x = NAG_ALLOC((n) * (m), double)) ||
        !(inc = NAG_ALLOC(n, Integer)) || !(isx = NAG_ALLOC(m, Integer)) ||
        !(nic = NAG_ALLOC(k, Integer))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
    tdx = m;
    tdcmeans = nvar;
  } else {
    printf("Invalid n or nvar or m or k.\n");
    exit_status = 1;
    return exit_status;
  }
  if (*weight == 'W') {
    for (i = 0; i < n; ++i) {
      for (j = 0; j < m; ++j)
        scanf("%lf", &X(i, j));
      scanf("%lf", &wt[i]);
    }
    wtptr = wt;
  } else {
    for (i = 0; i < n; ++i) {
      for (j = 0; j < m; ++j)
        scanf("%lf", &X(i, j));
    }
    wtptr = 0;
  }
  for (i = 0; i < k; ++i) {
    for (j = 0; j < nvar; ++j)
      scanf("%lf", &CMEANS(i, j));
  }
  for (j = 0; j < m; ++j)
    scanf("%" NAG_IFMT "", &isx[j]);

  /* nag_mv_cluster_kmeans (g03efc).
   * K-means
   */
  nag_mv_cluster_kmeans(n, m, x, tdx, isx, nvar, k, cmeans, tdcmeans, wtptr,
                        inc, nic, css, csw, maxit, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_mv_cluster_kmeans (g03efc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  printf("\nThe cluster each point belongs to\n");
  for (i = 0; i < n; ++i)
    printf(" %6" NAG_IFMT "%s", inc[i], (i + 1) % 10 ? "" : "\n");

  printf("\n\nThe number of points in each cluster\n");
  for (i = 0; i < k; ++i)
    printf(" %6" NAG_IFMT "", nic[i]);

  printf("\n\nThe within-cluster sum of weights of each cluster\n");
  for (i = 0; i < k; ++i)
    printf(" %9.2f", csw[i]);

  printf("\n\nThe within-cluster sum of squares of each cluster\n\n");
  for (i = 0; i < k; ++i)
    printf(" %13.4f", css[i]);

  printf("\n\nThe final cluster centres\n");
  printf("                  1       2       3       4       5\n");
  for (i = 0; i < k; ++i) {
    printf(" %5" NAG_IFMT "     ", i + 1);
    for (j = 0; j < nvar; ++j)
      printf("%8.4f", CMEANS(i, j));
    printf("\n");
  }
END:
  NAG_FREE(cmeans);
  NAG_FREE(css);
  NAG_FREE(csw);
  NAG_FREE(wt);
  NAG_FREE(x);
  NAG_FREE(inc);
  NAG_FREE(isx);
  NAG_FREE(nic);
  return exit_status;
}