relx.c

数据挖掘中的一算法 relim算法

/*----------------------------------------------------------------------
  File    : relx.c
  Contents: relim algorithm for finding frequent item sets
            (extended version, supporting penalized item insertions)
  Author  : Christian Borgelt
  History : 05.11.2004 file created from eclat.c
            17.11.2004 first reasonably fast version completed
            18.11.2004 start of loop over transactions lists improved
            20.11.2004 transaction tree version added
            23.11.2004 absolute/relative support output changed
            09.12.2004 filter added (binary logarithm of supp. quotient)
            12.12.2004 penalized insertion of missing items added
----------------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <limits.h>
#include <float.h>
#include <math.h>
#include <time.h>
#include <assert.h>
#include "scan.h"
#include "tract.h"
#ifdef STORAGE
#include "storage.h"
#endif

/*----------------------------------------------------------------------
  Preprocessor Definitions
----------------------------------------------------------------------*/
#define PRGNAME     "relx"
#define DESCRIPTION "find frequent item sets with item insertions"
#define VERSION     "version 1.2 (2004.12.28)         " \
                    "(c) 2004   Christian Borgelt"

/* --- marker --- */
#define RE_EOT      INT_MIN     /* end of transaction marker */

/* --- output flags --- */
#define OF_REL      0x01        /* print relative support */
#define OF_ABS      0x02        /* print absolute support */
#define OF_DEV      0x04        /* print deviation from indep. occ. */
#define OF_SCANF    0x08        /* convert names to scanable form */

/* --- error codes --- */
#define E_OPTION    (-5)        /* unknown option */
#define E_OPTARG    (-6)        /* missing option argument */
#define E_ARGCNT    (-7)        /* too few/many arguments */
#define E_STDIN     (-8)        /* double assignment of stdin */
#define E_SUPP      (-9)        /* invalid item set support */
#define E_ITEMCNT  (-10)        /* invalid number of items */
#define E_NOTAS    (-11)        /* no items or transactions */
#define E_PENEXP   (-12)        /* insertion penalty expected */
#define E_ILLPEN   (-13)        /* illegal insertion penalty */
#define E_UNKNOWN  (-18)        /* unknown error */

#ifndef QUIET                   /* if not quiet version */
#define MSG(x)        x         /* print messages */
#else                           /* if quiet version */
#define MSG(x)                  /* suppress messages */
#endif

#define SEC_SINCE(t)  ((clock()-(t)) /(double)CLOCKS_PER_SEC)
#define RECCNT(s)     (tfs_reccnt(is_tfscan(s)) \
                      + ((tfs_delim(is_tfscan(s)) == TFS_REC) ? 0 : 1))
#define BUFFER(s)     tfs_buf(is_tfscan(s))

/*----------------------------------------------------------------------
  Type Definitions
----------------------------------------------------------------------*/
typedef int REPFN (int *ids, int cnt, float supp);

typedef struct _tale {          /* --- transaction list element --- */
  struct _tale *succ;           /* pointer to successor element */
  int          *items;          /* items in the transaction */
  float        wgt;             /* transaction weight */
} TALE;                         /* (transaction list element) */

typedef struct {                /* --- transaction (tree) list --- */
  TALE   *head;                 /* head element of the list */
  float  supp;                  /* number of transactions */
} TALIST;                       /* (transaction (tree) list) */

typedef struct {                /* --- recursive elimination search */
  int    cnt;                   /* total number of items */
  int    min;                   /* minimum number of items */
  int    max;                   /* maximum number of items */
  int    trcnt;                 /* total number of transactions */
  float  supp;                  /* minimum support (number of trans.) */
  float  minwgt;                /* minimal transaction weight */
  float  *pens;                 /* insertion penalties per item */
  REPFN  *report;               /* report function for results */
  int    isc;                   /* number of frequent item sets */
  TALIST **lists;               /* vectors of trans. (tree) lists */
  TALE   **elems;               /* vectors of list elements */
  int    items[1];              /* item vector for reporting */
} RELIM;                        /* (recursive elimination search) */

/*----------------------------------------------------------------------
  Constants
----------------------------------------------------------------------*/
#define LN_2       0.69314718055994530942   /* ln(2) */

#ifndef QUIET                   /* if not quiet version */
/* --- error messages --- */
static const char *errmsgs[] = {
  /* E_NONE      0 */  "no error\n",
  /* E_NOMEM    -1 */  "not enough memory\n",
  /* E_FOPEN    -2 */  "cannot open file %s\n",
  /* E_FREAD    -3 */  "read error on file %s\n",
  /* E_FWRITE   -4 */  "write error on file %s\n",
  /* E_OPTION   -5 */  "unknown option -%c\n",
  /* E_OPTARG   -6 */  "missing option argument\n",
  /* E_ARGCNT   -7 */  "wrong number of arguments\n",
  /* E_STDIN    -8 */  "double assignment of standard input\n",
  /* E_SUPP     -9 */  "invalid minimal support %g%%\n",
  /* E_ITEMCNT -10 */  "invalid number of items %d\n",
  /* E_NOTAS   -11 */  "no items or transactions to work on\n",
  /*    -12 to -15 */  NULL, NULL, NULL, NULL,
  /* E_ITEMEXP -16 */  "file %s, record %d: item expected\n",
  /* E_DUPITEM -17 */  "file %s, record %d: duplicate item %s\n",
  /* E_UNKNOWN -18 */  "unknown error\n"
};
#endif

/*----------------------------------------------------------------------
  Global Variables
----------------------------------------------------------------------*/
#ifndef QUIET
static char    *prgname;        /* program name for error messages */
#endif
static ITEMSET *itemset = NULL; /* item set */
static TASET   *taset   = NULL; /* transaction set */
static FILE    *in      = NULL; /* input  file */
static FILE    *out     = NULL; /* output file */
static int     tacnt    = 0;    /* number of transactions */
static double  mindev   = -DBL_MAX; /* minimal value of deviation */
static double  *logfs   = NULL;     /* logarithms of item frequencies */
static float   *pens    = NULL;     /* insertion penalties per item */
static int     flags    = OF_REL;   /* output flags */
static char    *fmt     = "%.1f";   /* output format for support */
static char    buf[4*TFS_SIZE+4];   /* buffer for formatting */

/*----------------------------------------------------------------------
  Item Set Report Function
----------------------------------------------------------------------*/

static int report (int *ids, int cnt, float supp)
{                               /* --- report a frequent item set */
  int        i;                 /* loop variable */
  const char *name;             /* buffer for item name */
  double     dev;               /* deviation from indep. occurrence */

  assert(ids);                  /* check the function arguments */
  if (flags & OF_DEV) {         /* if to filter w.r.t. deviation */
    for (dev = 0, i = cnt; --i >= 0; )
      dev += logfs[ids[i]];     /* sum the logs of the item freqs. */
    dev = (log(supp/(double)tacnt) -dev) /LN_2;
    if (dev < mindev) return 0; /* compute and check the deviation */
  }                             /* from an independent occurrence */
  for (i = 0; i < cnt; i++) {   /* traverse the item set */
    name = is_name(itemset, ids[i]);
    if (flags & OF_SCANF) {     /* convert to scanable form */
      sc_format(buf, name, 0); name = buf; }
    fputs(name, out); fputc(' ', out);
  }                             /* print the item names */
  fputs(" (", out);             /* print rel. and abs. support */
  if (flags & OF_REL) { fprintf(out, fmt, (supp/(double)tacnt) *100);
                        fputs((flags & OF_ABS) ? "%/" : "%", out); }
  if (flags & OF_ABS) { fprintf(out, fmt, supp); }
  if (flags & OF_DEV) { fputs(", ", out); fprintf(out, fmt, dev); }
  fputs(")\n", out);            /* terminate the support output */
  return 1;                     /* return 'reported 1 item set' */
}  /* report() */

/*----------------------------------------------------------------------
  Recursive Elimination Functions
----------------------------------------------------------------------*/

static int re_vecs (TALIST *lists, int d, int i, RELIM *re)
{                               /* --- recursive elimination */
  int    item;                  /* loop variable, buffer */
  TALIST *subls, *s;            /* lists of subset of transactions */
  TALE   *elems;                /* elements of transaction lists */
  TALE   *src, *dst, *buf;      /* to traverse the transaction lists */
  float  pen;                   /* insertion penalty for an item */

  subls = re->lists[d];         /* get the subset lists vector */
  if (!subls) {                 /* if it does not exist yet */
    re->lists[d] = subls = (TALIST*)calloc(re->cnt+1, sizeof(TALIST));
    if (!subls) return -1;      /* create a new subset lists vector */
  }                             /* and store it in the vector buffer */
  elems = re->elems[d];         /* get the list elements vector */
  if (!elems) {                 /* if it does not exist yet */
    re->elems[d] = elems = (TALE*)  malloc(re->trcnt *sizeof(TALE));
    if (!elems) return -1;      /* create a new list elements vector */
  }                             /* and store it in the vector buffer */
  for (d++; 1; ) {              /* traverse the transaction lists */
    s = subls +re->cnt;         /* clear special transaction sublist */
    s->head = NULL; s->supp = 0;/* (collecting empty transactions) */
    s = lists +i;               /* get the next transaction list */

    /* -- process transactions not containing item i -- */
    dst = elems;                /* traverse the following lists */
    if (re->pens                /* if insertion costs are given */
    &&  (d <= re->max)) {       /* and maximum size not reached */
      for (pen = re->pens[item = i]; ++item <= re->cnt; ) {
        for (src = lists[item].head; src; src = src->succ) {
          dst->wgt = src->wgt *pen;
          if (dst->wgt < re->minwgt)
            continue;           /* check the minimum trans. weight */
          s->supp += dst->wgt;  /* and process trans. if sufficient */
          subls[item].supp += dst->wgt;
          dst->items = src->items;