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make_cp_list.c

/* SCCS @(#)make_cp_list.c    1.4 07/26/00 */
/*
** This routine creates the list of unique complexity parameters.
** The list is maintained in sorted order.  If two parameters are within
** "cplist_epsilon" of one another, then only the larger of them is
** retained.
**       CHANGE: 7/2000, the "cplist-epsilon" logic moved to S code
**   I want the list sorted with the largest cp at the top of the list, since
** that is the order that the CP table will be printed in.
**
**    After the partition routine is done, each node is labeled with the
** complexity parameter appropriate if that node were the top of the tree.
** However, if there is a more vunerable node further up, the node in
** question will actually have the smaller complexity parameter; it will
** be removed when its parent collapses. So this routine also adjusts each
** C.P. to = minimum(my C.P., parent's C.P.).
**
**   This routine is called at the top level by rpart, after rpart has
** initialized the first member of the linked cp-list, set its number of
** splits to zero, and its risk to that for no splits at all.  This routine
** allocates and links in the rest of the cp-list.  The make_cp_table
** routine then fills in the rest of the variables in the list.
**
**  node *me;         pointer to my node structure  
**  double parent;    complexity of my parent node 
**
**   When it comes time to cross-validate, we fill in xrisk and xstd
*/
#include <math.h>
#include "rpart.h"
#include "node.h"
#include "rpartS.h"
#include "rpartproto.h"

void make_cp_list(struct node *me, double parent, struct cptable *cptable_head)
    {
    double me_cp;
    struct cptable *cplist, *cptemp = NULL;

    if (me->complexity > parent) me->complexity = parent;
    me_cp = me->complexity;
    if (me_cp < rp.alpha) me_cp = rp.alpha;    /*table should go no lower */
    if (me->leftson != 0) {
       make_cp_list(me->leftson, me_cp, cptable_head);
       make_cp_list(me->rightson,me_cp, cptable_head);
       }

    if (me_cp < parent) {  /*if not, then it can't be unique */
      for (cplist= cptable_head; cplist !=0; cplist= cplist->forward) {
          /* am I tied? */
          if (me_cp == cplist->cp) return;  /* exact ties */

          if (me_cp > cplist->cp) break;
          cptemp = cplist;
          }

      /* insert new stuff after cptemp */
      cplist = (struct cptable *) CALLOC(1, sizeof(struct cptable));
      cplist->cp = me_cp;
      cplist->xrisk = 0;
      cplist->xstd  =0;
      cplist->back = cptemp;
      cplist->forward = cptemp->forward;
      if (cptemp->forward!=0) (cptemp->forward)->back = cplist;
        else  cptable_tail = cplist;
      cptemp->forward = cplist;
      rp.num_unique_cp++;
      return;
      }
    }

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