NAG Library Manual, Mark 28.7
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_mv_cluster_hier (g03ecc) Example Program.
 *
 * Copyright 2022 Numerical Algorithms Group.
 *
 * Mark 28.7, 2022.
 *
 */

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

#define X(I, J) x[(I)*tdx + J]
int main(void) {
  Integer exit_status = 0, i, j, m, n, nsym, tdx;
  Integer *ilc = 0, *iord = 0, *isx = 0, *iuc = 0;
  char **c = 0, name[40][2];
  double dmin_, dstep, ydist;
  double *cd = 0, *d = 0, *dord = 0, *s = 0, *x = 0;
  char nag_enum_arg[40];
  Nag_ClusterMethod method;
  Nag_DistanceType dist;
  Nag_MatUpdate update;
  Nag_VarScaleType scale;
  NagError fail;

  INIT_FAIL(fail);

  printf("nag_mv_cluster_hier (g03ecc) Example Program "
         "Results\n\n");

  /* Skip heading in data file  */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "", &n);
  scanf("%" NAG_IFMT "", &m);

  if (n >= 2 && m >= 1) {
    if (!(cd = NAG_ALLOC(n - 1, double)) ||
        !(d = NAG_ALLOC(n * (n - 1) / 2, double)) ||
        !(dord = NAG_ALLOC(n, double)) || !(s = NAG_ALLOC(m, double)) ||
        !(x = NAG_ALLOC(n * m, double)) || !(ilc = NAG_ALLOC(n - 1, Integer)) ||
        !(iord = NAG_ALLOC(n, Integer)) || !(isx = NAG_ALLOC(m, Integer)) ||
        !(iuc = NAG_ALLOC(n - 1, Integer))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
    tdx = m;
  } else {
    printf("Invalid n or m.\n");
    exit_status = 1;
    return exit_status;
  }
  scanf("%39s", nag_enum_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  method = (Nag_ClusterMethod)nag_enum_name_to_value(nag_enum_arg);
  scanf("%39s", nag_enum_arg);
  update = (Nag_MatUpdate)nag_enum_name_to_value(nag_enum_arg);
  scanf("%39s", nag_enum_arg);
  dist = (Nag_DistanceType)nag_enum_name_to_value(nag_enum_arg);
  scanf("%39s", nag_enum_arg);
  scale = (Nag_VarScaleType)nag_enum_name_to_value(nag_enum_arg);

  for (j = 0; j < n; ++j) {
    for (i = 0; i < m; ++i)
      scanf("%lf", &X(j, i));
    scanf("%1s", name[j]);
  }
  for (i = 0; i < m; ++i)
    scanf("%" NAG_IFMT "", &isx[i]);
  for (i = 0; i < m; ++i)
    scanf("%lf", &s[i]);

  /* Compute the distance matrix */
  /* nag_mv_distance_mat (g03eac).
   * Compute distance (dissimilarity) matrix
   */
  nag_mv_distance_mat(update, dist, scale, n, m, x, tdx, isx, s, d, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_mv_distance_mat (g03eac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Perform clustering */
  /* nag_mv_cluster_hier (g03ecc).
   * Hierarchical cluster analysis
   */
  nag_mv_cluster_hier(method, n, d, ilc, iuc, cd, iord, dord, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_mv_cluster_hier (g03ecc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  printf("\n   Distance   Clusters Joined\n\n");
  for (i = 1; i <= n - 1; ++i)
    printf("%10.3f     %3s%3s\n", cd[i - 1], name[ilc[i - 1] - 1],
           name[iuc[i - 1] - 1]);

  /* Produce dendrogram */
  nsym = 20;
  dmin_ = 0.0;
  dstep = cd[n - 2] / (double)nsym;
  /* nag_mv_cluster_hier_dendrogram (g03ehc).
   * Construct dendrogram following
   * nag_mv_cluster_hier (g03ecc)
   */
  nag_mv_cluster_hier_dendrogram(Nag_DendSouth, n, dord, dmin_, dstep, nsym, &c,
                                 &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_mv_cluster_hier_dendrogram (g03ehc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }
  printf("\n");
  printf("Dendrogram ");
  printf("\n");
  printf("\n");
  ydist = cd[n - 2];
  for (i = 0; i < nsym; ++i) {
    if ((i + 1) % 3 == 1) {
      printf("%10.3f%6s", ydist, "");
      printf("%s", c[i]);
      printf("\n");
    } else {
      printf("%16s%s", "", c[i]);
      printf("\n");
    }
    ydist -= dstep;
  }
  printf("\n");
  printf("%14s", "");
  for (i = 0; i < n; ++i) {
    printf("%3s", name[iord[i] - 1]);
  }
  printf("\n");
  /* nag_mv_dend_free (g03xzc).
   * Frees memory allocated to the dendrogram array in
   * nag_mv_cluster_hier_dendrogram (g03ehc)
   */
  nag_mv_dend_free(&c);

END:
  NAG_FREE(cd);
  NAG_FREE(d);
  NAG_FREE(dord);
  NAG_FREE(s);
  NAG_FREE(x);
  NAG_FREE(ilc);
  NAG_FREE(iord);
  NAG_FREE(isx);
  NAG_FREE(iuc);

  return exit_status;
}