OSDN Git Service

Significantly improve ranking:
authorTeodor Sigaev <teodor@sigaev.ru>
Thu, 2 Mar 2006 19:07:19 +0000 (19:07 +0000)
committerTeodor Sigaev <teodor@sigaev.ru>
Thu, 2 Mar 2006 19:07:19 +0000 (19:07 +0000)
1) rank_cd now use weight of lexemes
2) rank_cd and rank can use any combination of normalization methods:
        no normalization
        normalization by log(length of document)
        -----/------- by length of document
        -----/------- by number of unique word in document
        -----/------- by log(number of unique word in document)
        -----/------- by number of covers (only rank_cd)

Improve cover's search.

TODO: changes in documentation

contrib/tsearch2/expected/tsearch2.out
contrib/tsearch2/rank.c
contrib/tsearch2/tsearch.sql.in

index 8fb16b0..2a60e31 100644 (file)
@@ -2315,9 +2315,9 @@ An hour of storm to place
 The sculpture of these granite seams,
 Upon a woman s face. E.  J.  Pratt  (1882 1964)
 '), to_tsquery('sea&thousand&years'));
- rank_cd 
----------
-     1.2
+  rank_cd  
+-----------
+ 0.0555556
 (1 row)
 
 select rank_cd(to_tsvector('Erosion It took the sea a thousand years,
@@ -2329,9 +2329,9 @@ An hour of storm to place
 The sculpture of these granite seams,
 Upon a woman s face. E.  J.  Pratt  (1882 1964)
 '), to_tsquery('granite&sea'));
- rank_cd  
-----------
- 0.880303
 rank_cd  
+-----------
+ 0.0238095
 (1 row)
 
 select rank_cd(to_tsvector('Erosion It took the sea a thousand years,
@@ -2345,7 +2345,7 @@ Upon a woman s face. E.  J.  Pratt  (1882 1964)
 '), to_tsquery('sea'));
  rank_cd 
 ---------
-       2
+     0.2
 (1 row)
 
 select get_covers(to_tsvector('Erosion It took the sea a thousand years,
index a8c30bf..29732c1 100644 (file)
@@ -41,7 +41,13 @@ static float weights[] = {0.1, 0.2, 0.4, 1.0};
 
 #define wpos(wep)      ( w[ WEP_GETWEIGHT(wep) ] )
 
-#define DEF_NORM_METHOD 0
+#define        RANK_NO_NORM            0x00
+#define RANK_NORM_LOGLENGTH    0x01
+#define RANK_NORM_LENGTH       0x02
+#define        RANK_NORM_EXTDIST       0x04
+#define RANK_NORM_UNIQ         0x08
+#define RANK_NORM_LOGUNIQ      0x10
+#define DEF_NORM_METHOD        RANK_NO_NORM
 
 static float calc_rank_or(float *w, tsvector * t, QUERYTYPE * q);
 static float calc_rank_and(float *w, tsvector * t, QUERYTYPE * q);
@@ -328,23 +334,21 @@ calc_rank(float *w, tsvector * t, QUERYTYPE * q, int4 method)
        if (res < 0)
                res = 1e-20;
 
-       switch (method)
-       {
-               case 0:
-                       break;
-               case 1:
-                       res /= log((float) (cnt_length(t) + 1)) / log(2.0);
-                       break;
-               case 2:
-                       len = cnt_length(t);
-                       if (len > 0)
-                               res /= (float) len;
-                       break;
-               default:
-                       /* internal error */
-                       elog(ERROR, "unrecognized normalization method: %d", method);
+       if ( (method & RANK_NORM_LOGLENGTH) && t->size>0 )
+               res /= log((double) (cnt_length(t) + 1)) / log(2.0);
+
+       if ( method & RANK_NORM_LENGTH ) {
+               len = cnt_length(t);
+               if ( len>0 )
+                       res /= (float) len;
        }
 
+       if ( (method & RANK_NORM_UNIQ) && t->size > 0 )
+               res /= (float)( t->size );
+
+       if ( (method & RANK_NORM_LOGUNIQ) && t->size > 0 )
+               res /= log((double) (t->size + 1)) / log(2.0);
+
        return res;
 }
 
@@ -420,6 +424,7 @@ typedef struct
        ITEM      **item;
        int16           nitem;
        bool            needfree;
+       uint8           wclass;
        int32           pos;
 }      DocRepresentation;
 
@@ -452,19 +457,28 @@ reset_istrue_flag(QUERYTYPE * query)
        }
 }
 
+typedef struct {
+       int     pos;
+       int     p;
+       int     q;
+       DocRepresentation       *begin;
+       DocRepresentation       *end;
+} Extention;
+
+
 static bool
-Cover(DocRepresentation * doc, int len, QUERYTYPE * query, int *pos, int *p, int *q)
+Cover(DocRepresentation * doc, int len, QUERYTYPE * query, Extention *ext)
 {
        DocRepresentation *ptr;
-       int                     lastpos = *pos;
+       int                     lastpos = ext->pos;
        int                     i;
        bool            found = false;
 
        reset_istrue_flag(query);
 
-       *p = 0x7fffffff;
-       *q = 0;
-       ptr = doc + *pos;
+       ext->p = 0x7fffffff;
+       ext->q = 0;
+       ptr = doc + ext->pos;
 
        /* find upper bound of cover from current position, move up */
        while (ptr - doc < len)
@@ -473,9 +487,10 @@ Cover(DocRepresentation * doc, int len, QUERYTYPE * query, int *pos, int *p, int
                        ptr->item[i]->istrue = 1;
                if (TS_execute(GETQUERY(query), NULL, false, checkcondition_ITEM))
                {
-                       if (ptr->pos > *q)
+                       if (ptr->pos > ext->q)
                        {
-                               *q = ptr->pos;
+                               ext->q = ptr->pos;
+                               ext->end = ptr;
                                lastpos = ptr - doc;
                                found = true;
                        }
@@ -498,25 +513,27 @@ Cover(DocRepresentation * doc, int len, QUERYTYPE * query, int *pos, int *p, int
                        ptr->item[i]->istrue = 1;
                if (TS_execute(GETQUERY(query), NULL, true, checkcondition_ITEM))
                {
-                       if (ptr->pos < *p)
-                               *p = ptr->pos;
+                       if (ptr->pos < ext->p) {
+                               ext->begin = ptr;
+                               ext->p = ptr->pos;
+                       }
                        break;
                }
                ptr--;
        }
 
-       if (*p <= *q)
+       if (ext->p <= ext->q)
        {
                /*
                 * set position for next try to next lexeme after begining of founded
                 * cover
                 */
-               *pos = (ptr - doc) + 1;
+               ext->pos = (ptr - doc) + 1;
                return true;
        }
 
-       (*pos)++;
-       return Cover(doc, len, query, pos, p, q);
+       ext->pos++;
+       return Cover(doc, len, query, ext);
 }
 
 static DocRepresentation *
@@ -593,6 +610,7 @@ get_docrep(tsvector * txt, QUERYTYPE * query, int *doclen)
                                doc[cur].item = doc[cur - 1].item;
                        }
                        doc[cur].pos = WEP_GETPOS(post[j]);
+                       doc[cur].wclass = WEP_GETWEIGHT(post[j]);
                        cur++;
                }
        }
@@ -610,61 +628,110 @@ get_docrep(tsvector * txt, QUERYTYPE * query, int *doclen)
        return NULL;
 }
 
-
-Datum
-rank_cd(PG_FUNCTION_ARGS)
-{
-       int                     K = PG_GETARG_INT32(0);
-       tsvector   *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(1));
-       QUERYTYPE  *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(2));
-       int                     method = DEF_NORM_METHOD;
+static float4
+calc_rank_cd(float4 *arrdata, tsvector *txt, QUERYTYPE *query, int method) {
        DocRepresentation *doc;
-       float           res = 0.0;
-       int                     p = 0,
-                               q = 0,
-                               len,
-                               cur,
+       int                     len,
                                i,
                                doclen = 0;
+       Extention       ext;
+       double          Wdoc = 0.0;
+       double          invws[lengthof(weights)];
+       double          SumDist=0.0, PrevExtPos=0.0, CurExtPos=0.0;
+       int             NExtent=0;
 
-       doc = get_docrep(txt, query, &doclen);
-       if (!doc)
+       for (i = 0; i < lengthof(weights); i++)
        {
-               PG_FREE_IF_COPY(txt, 1);
-               PG_FREE_IF_COPY(query, 2);
-               PG_RETURN_FLOAT4(0.0);
+               invws[i] = ((double)((arrdata[i] >= 0) ? arrdata[i] : weights[i]));
+               if (invws[i] > 1.0)
+                       ereport(ERROR,
+                                       (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                                        errmsg("weight out of range")));
+               invws[i] = 1.0/invws[i]; 
        }
 
-       cur = 0;
-       if (K <= 0)
-               K = 4;
-       while (Cover(doc, doclen, query, &cur, &p, &q))
-               res += (q - p + 1 > K) ? ((float) K) / ((float) (q - p + 1)) : 1.0;
+       doc = get_docrep(txt, query, &doclen);
+       if (!doc) 
+               return 0.0;
 
-       if (PG_NARGS() == 4)
-               method = PG_GETARG_INT32(3);
+       MemSet( &ext, 0, sizeof(Extention) );
+       while (Cover(doc, doclen, query, &ext)) {
+               double  Cpos = 0.0;
+               double  InvSum = 0.0;
+               DocRepresentation *ptr = ext.begin;
 
-       switch (method)
-       {
-               case 0:
-                       break;
-               case 1:
-                       res /= log((float) (cnt_length(txt) + 1));
-                       break;
-               case 2:
-                       len = cnt_length(txt);
-                       if (len > 0)
-                               res /= (float) len;
-                       break;
-               default:
-                       /* internal error */
-                       elog(ERROR, "unrecognized normalization method: %d", method);
+               while ( ptr<=ext.end ) {
+                       InvSum += invws[ ptr->wclass ];
+                       ptr++;
+               }
+
+               Cpos = ((double)( ext.end-ext.begin+1 )) / InvSum;
+               Wdoc += Cpos / ( (double)(( 1 + (ext.q - ext.p) - (ext.end - ext.begin) )) ); 
+
+               CurExtPos = ((double)(ext.q + ext.p))/2.0; 
+               if ( NExtent>0 && CurExtPos > PrevExtPos /* prevent devision by zero in a case of multiple lexize */ ) 
+                       SumDist += 1.0/( CurExtPos - PrevExtPos );
+
+               PrevExtPos = CurExtPos;
+               NExtent++; 
+       }
+
+       if ( (method & RANK_NORM_LOGLENGTH) && txt->size > 0 )
+               Wdoc /= log((double) (cnt_length(txt) + 1));
+
+       if ( method & RANK_NORM_LENGTH ) {
+               len = cnt_length(txt);
+               if ( len>0 )
+                       Wdoc /= (double) len;
        }
 
+       if ( (method & RANK_NORM_EXTDIST) && SumDist > 0 ) 
+               Wdoc /= ((double)NExtent) / SumDist;
+
+       if ( (method & RANK_NORM_UNIQ) && txt->size > 0 )
+               Wdoc /= (double)( txt->size );
+
+       if ( (method & RANK_NORM_LOGUNIQ) && txt->size > 0 )
+               Wdoc /= log((double) (txt->size + 1)) / log(2.0);
+
        for (i = 0; i < doclen; i++)
                if (doc[i].needfree)
                        pfree(doc[i].item);
        pfree(doc);
+
+       return (float4)Wdoc;
+} 
+
+Datum
+rank_cd(PG_FUNCTION_ARGS)
+{
+       ArrayType *win =  (ArrayType *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+       tsvector   *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(1));
+       QUERYTYPE  *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(2));
+       int                     method = DEF_NORM_METHOD;
+       float4          res;
+
+       if (ARR_NDIM(win) != 1)
+               ereport(ERROR,
+                               (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+                                errmsg("array of weight must be one-dimensional")));
+
+       if (ARRNELEMS(win) < lengthof(weights))
+               ereport(ERROR,
+                               (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+                                errmsg("array of weight is too short")));
+
+       if (ARR_HASNULL(win))
+               ereport(ERROR,
+                               (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+                                errmsg("array of weight must not contain nulls")));
+
+       if (PG_NARGS() == 4)
+               method = PG_GETARG_INT32(3);
+
+       res = calc_rank_cd( (float4 *) ARR_DATA_PTR(win), txt, query, method);
+
+       PG_FREE_IF_COPY(win, 0);
        PG_FREE_IF_COPY(txt, 1);
        PG_FREE_IF_COPY(query, 2);
 
@@ -675,13 +742,16 @@ rank_cd(PG_FUNCTION_ARGS)
 Datum
 rank_cd_def(PG_FUNCTION_ARGS)
 {
-       PG_RETURN_DATUM(DirectFunctionCall4(
-                                                                               rank_cd,
-                                                                               Int32GetDatum(-1),
-                                                                               PG_GETARG_DATUM(0),
-                                                                               PG_GETARG_DATUM(1),
-         (PG_NARGS() == 3) ? PG_GETARG_DATUM(2) : Int32GetDatum(DEF_NORM_METHOD)
-                                                                               ));
+       tsvector   *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+       QUERYTYPE  *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(1));
+       float4 res;
+
+       res = calc_rank_cd( weights, txt, query, (PG_NARGS() == 3) ? PG_GETARG_DATUM(2) : DEF_NORM_METHOD);
+       
+       PG_FREE_IF_COPY(txt, 1);
+       PG_FREE_IF_COPY(query, 2);
+
+       PG_RETURN_FLOAT4(res);
 }
 
 /**************debug*************/
@@ -721,11 +791,9 @@ get_covers(PG_FUNCTION_ARGS)
        text       *out;
        char       *cptr;
        DocRepresentation *doc;
-       int                     pos = 0,
-                               p,
-                               q,
-                               olddwpos = 0;
+       int                     olddwpos = 0;
        int                     ncover = 1;
+       Extention       ext;
 
        doc = get_docrep(txt, query, &rlen);
 
@@ -765,14 +833,15 @@ get_covers(PG_FUNCTION_ARGS)
        }
        qsort((void *) dw, dlen, sizeof(DocWord), compareDocWord);
 
-       while (Cover(doc, rlen, query, &pos, &p, &q))
+       MemSet( &ext, 0, sizeof(Extention) );
+       while (Cover(doc, rlen, query, &ext))
        {
                dwptr = dw + olddwpos;
-               while (dwptr->pos < p && dwptr - dw < dlen)
+               while (dwptr->pos < ext.p && dwptr - dw < dlen)
                        dwptr++;
                olddwpos = dwptr - dw;
                dwptr->start = ncover;
-               while (dwptr->pos < q + 1 && dwptr - dw < dlen)
+               while (dwptr->pos < ext.q + 1 && dwptr - dw < dlen)
                        dwptr++;
                (dwptr - 1)->finish = ncover;
                len += 4 /* {}+two spaces */ + 2 * 16 /* numbers */ ;
index c30a80e..0ab0887 100644 (file)
@@ -534,12 +534,12 @@ RETURNS float4
 AS 'MODULE_PATHNAME', 'rank_def'
 LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;
 
-CREATE FUNCTION rank_cd(int4, tsvector, tsquery)
+CREATE FUNCTION rank_cd(float4[], tsvector, tsquery)
 RETURNS float4
 AS 'MODULE_PATHNAME'
 LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;
 
-CREATE FUNCTION rank_cd(int4, tsvector, tsquery, int4)
+CREATE FUNCTION rank_cd(float4[], tsvector, tsquery, int4)
 RETURNS float4
 AS 'MODULE_PATHNAME'
 LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;