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tesseract/dict/stopper.cpp

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top-skimming import from sf.net git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk/trunk@2 d0cd1f9f-072b-0410-8dd7-cf729c803f20
2007-03-08 04:03:40 +08:00
/******************************************************************************
** Filename: stopper.c
** Purpose: Stopping criteria for word classifier.
** Author: Dan Johnson
** History: Mon Apr 29 14:56:49 1991, DSJ, Created.
**
** (c) Copyright Hewlett-Packard Company, 1988.
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
** http://www.apache.org/licenses/LICENSE-2.0
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
******************************************************************************/
/**----------------------------------------------------------------------------
Include Files and Type Defines
----------------------------------------------------------------------------**/
#include "stopper.h"
#include "emalloc.h"
#include "matchdefs.h"
#include "debug.h"
#include "callcpp.h"
#include "permute.h"
#include "context.h"
#include "permnum.h"
#include "danerror.h"
#include "const.h"
#include "freelist.h"
#include "efio.h"
#include "globals.h"
#include "scanutils.h"
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#ifdef __UNIX__
#include <assert.h>
#endif
/* these are kludges - add appropriate .h file later */
extern float CertaintyScale; /* from subfeat.h */
#define MAX_WERD_SIZE 100
#define MAX_AMBIG_SIZE 3
#define DANGEROUS_AMBIGS "tessdata/DangAmbigs"
typedef LIST AMBIG_TABLE;
typedef struct
{
UINT8 Class;
UINT16 NumChunks;
float Certainty;
}
CHAR_CHOICE;
typedef struct
{
float Rating;
float Certainty;
FLOAT32 AdjustFactor;
int Length;
CHAR_CHOICE Blob[1];
} VIABLE_CHOICE_STRUCT;
typedef VIABLE_CHOICE_STRUCT *VIABLE_CHOICE;
typedef struct
{
VIABLE_CHOICE Choice;
float ChunkCertainty[MAX_NUM_CHUNKS];
UINT8 ChunkClass[MAX_NUM_CHUNKS];
}
EXPANDED_CHOICE;
/**----------------------------------------------------------------------------
Macros
----------------------------------------------------------------------------**/
#define BestCertainty(Choices) (((VIABLE_CHOICE) first (Choices))->Certainty)
#define BestRating(Choices) (((VIABLE_CHOICE) first (Choices))->Rating)
#define BestFactor(Choices) (((VIABLE_CHOICE) first (Choices))->AdjustFactor)
#define AmbigThreshold(F1,F2) (((F2) - (F1)) * AmbigThresholdGain - \
AmbigThresholdOffset)
/*---------------------------------------------------------------------------
Private Function Prototoypes
----------------------------------------------------------------------------*/
void AddNewChunk(VIABLE_CHOICE Choice, int Blob);
int AmbigsFound(char *Word,
char *CurrentChar,
const char *Tail,
LIST Ambigs,
DANGERR *fixpt);
int ChoiceSameAs(A_CHOICE *Choice, VIABLE_CHOICE ViableChoice);
int CmpChoiceRatings(void *arg1, //VIABLE_CHOICE Choice1,
void *arg2); //VIABLE_CHOICE Choice2);
void ExpandChoice(VIABLE_CHOICE Choice, EXPANDED_CHOICE *ExpandedChoice);
AMBIG_TABLE *FillAmbigTable();
int FreeBadChoice(void *item1, //VIABLE_CHOICE Choice,
void *item2); //EXPANDED_CHOICE *BestChoice);
int LengthOfShortestAlphaRun(register char *Word);
VIABLE_CHOICE NewViableChoice (A_CHOICE * Choice,
FLOAT32 AdjustFactor, float Certainties[]);
void PrintViableChoice(FILE *File, const char *Label, VIABLE_CHOICE Choice);
void ReplaceDuplicateChoice (VIABLE_CHOICE OldChoice,
A_CHOICE * NewChoice,
FLOAT32 AdjustFactor, float Certainties[]);
int StringSameAs(const char *String, VIABLE_CHOICE ViableChoice);
int UniformCertainties(CHOICES_LIST Choices, A_CHOICE *BestChoice);
/**----------------------------------------------------------------------------
Global Data Definitions and Declarations
----------------------------------------------------------------------------**/
/* Name of file containing potentially dangerous ambiguities */
static const char *DangerousAmbigs = DANGEROUS_AMBIGS;
/* Word for which stopper debug information should be printed to stdout */
static char *WordToDebug = NULL;
/* flag used to disable accumulation of word choices during compound word
permutation */
BOOL8 KeepWordChoices = TRUE;
/* additional certainty padding allowed before a word is rejected */
static FLOAT32 RejectOffset = 0.0;
/* structures to keep track of viable word choices */
static VIABLE_CHOICE BestRawChoice = NULL;
static LIST BestChoices = NIL;
static PIECES_STATE CurrentSegmentation;
make_float_var (NonDictCertainty, -2.50, MakeNonDictCertainty,
17, 2, SetNonDictCertainty,
"Certainty threshold for non-dict words");
make_float_var (RejectCertaintyOffset, 1.0, MakeRejectCertaintyOffset,
17, 3, SetRejectCertaintyOffset, "Reject certainty offset");
make_int_var (SmallWordSize, 2, MakeSmallWordSize,
17, 4, SetSmallWordSize,
"Size of dict word to be treated as non-dict word");
make_float_var (CertaintyPerChar, -0.50, MakeCertaintyPerChar,
17, 5, SetCertaintyPerChar,
"Certainty to add for each dict char above SmallWordSize");
make_float_var (CertaintyVariation, 3.0, MakeCertaintyVariation,
17, 6, SetCertaintyVariation,
"Max certaintly variation allowed in a word (in sigma)");
make_int_var (StopperDebugLevel, 0, MakeStopperDebugLevel,
17, 7, SetStopperDebugLevel, "Stopper debug level");
make_float_var (AmbigThresholdGain, 8.0, MakeAmbigThresholdGain,
17, 8, SetAmbigThresholdGain,
"Gain factor for ambiguity threshold");
make_float_var (AmbigThresholdOffset, 1.5, MakeAmbigThresholdOffset,
17, 9, SetAmbigThresholdOffset,
"Certainty offset for ambiguity threshold");
//extern char *demodir;
extern int first_pass;
INT_VAR (tessedit_truncate_wordchoice_log, 10, "Max words to keep in list");
/**----------------------------------------------------------------------------
Public Code
----------------------------------------------------------------------------**/
/*---------------------------------------------------------------------------*/
int AcceptableChoice(CHOICES_LIST Choices,
A_CHOICE *BestChoice,
A_CHOICE *RawChoice,
DANGERR *fixpt) {
/*
** Parameters:
** Choices choices for current segmentation
** BestChoice best choice for current segmentation
** RawChoice best raw choice for current segmentation
** Globals:
** NonDictCertainty certainty for a non-dict word
** SmallWordSize size of word to be treated as non-word
** CertaintyPerChar certainty to add for each dict char
** Operation: Return TRUE if the results from this segmentation are
** good enough to stop. Otherwise return FALSE.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Mon Apr 29 14:57:32 1991, DSJ, Created.
*/
float CertaintyThreshold = NonDictCertainty;
int WordSize;
if (fixpt != NULL)
fixpt->index = -1;
if ((BestChoice == NULL) || (class_string (BestChoice) == NULL))
return (FALSE);
if (StopperDebugLevel >= 1)
cprintf ("\nStopper: %s (word=%c, case=%c, punct=%c)\n",
class_string (BestChoice),
(valid_word (class_string (BestChoice)) ? 'y' : 'n'),
(case_ok (class_string (BestChoice)) ? 'y' : 'n'),
((punctuation_ok (class_string (BestChoice)) !=
-1) ? 'y' : 'n'));
if (valid_word (class_string (BestChoice)) &&
case_ok (class_string (BestChoice)) &&
punctuation_ok (class_string (BestChoice)) != -1) {
WordSize = LengthOfShortestAlphaRun (class_string (BestChoice));
WordSize -= SmallWordSize;
if (WordSize < 0)
WordSize = 0;
CertaintyThreshold += WordSize * CertaintyPerChar;
}
else if (stopper_numbers_on && valid_number (class_string (BestChoice))) {
CertaintyThreshold += stopper_numbers_on * CertaintyPerChar;
}
if (StopperDebugLevel >= 1)
cprintf ("Stopper: Certainty = %4.1f, Threshold = %4.1f\n",
class_certainty (BestChoice), CertaintyThreshold);
if (NoDangerousAmbig (class_string (BestChoice), fixpt)
&& class_certainty (BestChoice) > CertaintyThreshold &&
UniformCertainties (Choices, BestChoice))
return (TRUE);
else
return (FALSE);
} /* AcceptableChoice */
/*---------------------------------------------------------------------------*/
int AcceptableResult(A_CHOICE *BestChoice, A_CHOICE *RawChoice) {
/*
** Parameters:
** BestChoice best choice for current word
** RawChoice best raw choice for current word
** Globals:
** NonDictCertainty certainty for a non-dict word
** SmallWordSize size of word to be treated as non-word
** CertaintyPerChar certainty to add for each dict char
** BestChoices list of all good choices found
** RejectOffset allowed offset before a word is rejected
** Operation: Return FALSE if the best choice for the current word
** is questionable and should be tried again on the second
** pass or should be flagged to the user.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Thu May 9 14:05:05 1991, DSJ, Created.
*/
float CertaintyThreshold = NonDictCertainty - RejectOffset;
int WordSize;
if (StopperDebugLevel >= 1)
cprintf ("\nRejecter: %s (word=%c, case=%c, punct=%c, unambig=%c)\n",
class_string (BestChoice),
(valid_word (class_string (BestChoice)) ? 'y' : 'n'),
(case_ok (class_string (BestChoice)) ? 'y' : 'n'),
((punctuation_ok (class_string (BestChoice)) != -1) ? 'y' : 'n'),
((rest (BestChoices) != NIL) ? 'n' : 'y'));
if ((BestChoice == NULL) ||
(class_string (BestChoice) == NULL) || CurrentWordAmbig ())
return (FALSE);
if (valid_word (class_string (BestChoice)) &&
case_ok (class_string (BestChoice)) &&
punctuation_ok (class_string (BestChoice)) != -1) {
WordSize = LengthOfShortestAlphaRun (class_string (BestChoice));
WordSize -= SmallWordSize;
if (WordSize < 0)
WordSize = 0;
CertaintyThreshold += WordSize * CertaintyPerChar;
}
if (StopperDebugLevel >= 1)
cprintf ("Rejecter: Certainty = %4.1f, Threshold = %4.1f ",
class_certainty (BestChoice), CertaintyThreshold);
if (class_certainty (BestChoice) > CertaintyThreshold) {
if (StopperDebugLevel >= 1)
cprintf ("ACCEPTED\n");
return (TRUE);
}
else {
if (StopperDebugLevel >= 1)
cprintf ("REJECTED\n");
return (FALSE);
}
} /* AcceptableResult */
/*---------------------------------------------------------------------------*/
int AlternativeChoicesWorseThan(FLOAT32 Threshold) {
/*
** Parameters:
** Threshold minimum adjust factor for alternative choices
** Globals:
** BestChoices alternative choices for current word
** Operation: This routine returns TRUE if there are no alternative
** choices for the current word OR if all alternatives have
** an adjust factor worse than Threshold.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Mon Jun 3 09:36:31 1991, DSJ, Created.
*/
LIST Alternatives;
VIABLE_CHOICE Choice;
Alternatives = rest (BestChoices);
iterate(Alternatives) {
Choice = (VIABLE_CHOICE) first (Alternatives);
if (Choice->AdjustFactor <= Threshold)
return (FALSE);
}
return (TRUE);
} /* AlternativeChoicesWorseThan */
/*---------------------------------------------------------------------------*/
int CurrentBestChoiceIs(const char *Word) {
/*
** Parameters:
** Word string to compare to current best choice
** Globals:
** BestChoices set of best choices for current word
** Operation: Returns TRUE if Word is the same as the current best
** choice, FALSE otherwise.
** Return: TRUE or FALSE
** Exceptions: none
** History: Thu May 30 14:44:22 1991, DSJ, Created.
*/
return (BestChoices != NIL &&
StringSameAs (Word, (VIABLE_CHOICE) first (BestChoices)));
} /* CurrentBestChoiceIs */
/*---------------------------------------------------------------------------*/
FLOAT32 CurrentBestChoiceAdjustFactor() {
/*
** Parameters: none
** Globals:
** BestChoices set of best choices for current word
** Operation: Return the adjustment factor for the best choice for
** the current word.
** Return: Adjust factor for current best choice.
** Exceptions: none
** History: Thu May 30 14:48:24 1991, DSJ, Created.
*/
VIABLE_CHOICE BestChoice;
if (BestChoices == NIL)
return (MAX_FLOAT32);
BestChoice = (VIABLE_CHOICE) first (BestChoices);
return (BestChoice->AdjustFactor);
} /* CurrentBestChoiceAdjustFactor */
/*---------------------------------------------------------------------------*/
int CurrentWordAmbig() {
/*
** Parameters: none
** Globals:
** BestChoices set of best choices for current word
** Operation: This routine returns TRUE if there are multiple good
** choices for the current word and FALSE otherwise.
** Return: TRUE or FALSE
** Exceptions: none
** History: Wed May 22 15:38:38 1991, DSJ, Created.
*/
return (rest (BestChoices) != NIL);
} /* CurrentWordAmbig */
/*---------------------------------------------------------------------------*/
void DebugWordChoices() {
/*
** Parameters: none
** Globals:
** BestRawChoice
** BestChoices
** Operation: Print the current choices for this word to stdout.
** Return: none
** Exceptions: none
** History: Wed May 15 13:52:08 1991, DSJ, Created.
*/
LIST Choices;
int i;
char LabelString[80];
if (StopperDebugLevel >= 1 ||
WordToDebug && BestChoices &&
StringSameAs (WordToDebug, (VIABLE_CHOICE) first (BestChoices))) {
if (BestRawChoice)
PrintViableChoice (stdout, "\nBest Raw Choice: ", BestRawChoice);
i = 1;
Choices = BestChoices;
if (Choices)
cprintf ("\nBest Cooked Choices:\n");
iterate(Choices) {
sprintf (LabelString, "Cooked Choice #%d: ", i);
PrintViableChoice (stdout, LabelString,
(VIABLE_CHOICE) first (Choices));
i++;
}
}
} /* DebugWordChoices */
/*---------------------------------------------------------------------------*/
void FilterWordChoices() {
/*
** Parameters: none
** Globals:
** BestChoices set of choices for current word
** Operation: This routine removes from BestChoices all choices which
** are not within a reasonable range of the best choice.
** Return: none
** Exceptions: none
** History: Wed May 15 13:08:24 1991, DSJ, Created.
*/
EXPANDED_CHOICE BestChoice;
if (BestChoices == NIL || second (BestChoices) == NIL)
return;
/* compute certainties and class for each chunk in best choice */
ExpandChoice ((VIABLE_CHOICE_STRUCT *) first (BestChoices), &BestChoice);
set_rest (BestChoices, delete_d (rest (BestChoices),
&BestChoice, FreeBadChoice));
} /* FilterWordChoices */
/*---------------------------------------------------------------------------*/
void
FindClassifierErrors (FLOAT32 MinRating,
FLOAT32 MaxRating,
FLOAT32 RatingMargin, FLOAT32 Thresholds[]) {
/*
** Parameters:
** MinRating limits how tight to make a template
** MaxRating limits how loose to make a template
** RatingMargin amount of margin to put in template
** Thresholds[] place to put error thresholds
** Globals: none
** Operation: This routine compares the best choice for the current
** word to the best raw choice to determine which characters
** were classified incorrectly by the classifier. It then
** places a separate threshold into Thresholds for each
** character in the word. If the classifier was correct,
** MaxRating is placed into Thresholds. If the
** classifier was incorrect, the avg. match rating (error
** percentage) of the classifier's incorrect choice minus
** some margin is
** placed into thresholds. This can then be used by the
** caller to try to create a new template for the desired
** class that will classify the character with a rating better
** than the threshold value. The match rating placed into
** Thresholds is never allowed to be below MinRating in order
** to prevent trying to make overly tight templates.
** Return: none (results are placed in Thresholds)
** Exceptions: none
** History: Fri May 31 16:02:57 1991, DSJ, Created.
*/
EXPANDED_CHOICE BestRaw;
VIABLE_CHOICE Choice;
int i, j, Chunk;
FLOAT32 AvgRating;
int NumErrorChunks;
assert (BestChoices != NIL);
assert (BestRawChoice != NULL);
ExpandChoice(BestRawChoice, &BestRaw);
Choice = (VIABLE_CHOICE) first (BestChoices);
for (i = 0, Chunk = 0; i < Choice->Length; i++, Thresholds++) {
AvgRating = 0.0;
NumErrorChunks = 0;
for (j = 0; j < Choice->Blob[i].NumChunks; j++, Chunk++)
if (Choice->Blob[i].Class != BestRaw.ChunkClass[Chunk]) {
AvgRating += BestRaw.ChunkCertainty[Chunk];
NumErrorChunks++;
}
if (NumErrorChunks > 0) {
AvgRating /= NumErrorChunks;
*Thresholds = (AvgRating / -CertaintyScale) * (1.0 - RatingMargin);
}
else
*Thresholds = MaxRating;
if (*Thresholds > MaxRating)
*Thresholds = MaxRating;
if (*Thresholds < MinRating)
*Thresholds = MinRating;
}
} /* FindClassifierErrors */
/*---------------------------------------------------------------------------*/
void InitStopperVars() {
/*
** Parameters: none
** Globals: none
** Operation: Initializes the control variables used by the stopper.
** Return: none
** Exceptions: none
** History: Thu May 9 10:06:04 1991, DSJ, Created.
*/
VALUE dummy;
string_variable (DangerousAmbigs, "DangerousAmbigs", DANGEROUS_AMBIGS);
string_variable (WordToDebug, "WordToDebug", "");
MakeNonDictCertainty();
MakeRejectCertaintyOffset();
MakeSmallWordSize();
MakeCertaintyPerChar();
MakeCertaintyVariation();
MakeStopperDebugLevel();
MakeAmbigThresholdGain();
MakeAmbigThresholdOffset();
} /* InitStopperVars */
/*---------------------------------------------------------------------------*/
void InitChoiceAccum() {
/*
** Parameters: none
** Globals: none
** Operation: This routine initializes the data structures used to
** keep track the good word choices found for a word.
** Return: none
** Exceptions: none
** History: Fri May 17 07:59:00 1991, DSJ, Created.
*/
BLOB_WIDTH *BlobWidth, *End;
if (BestRawChoice)
memfree(BestRawChoice);
if (BestChoices)
destroy_nodes(BestChoices, memfree);
BestRawChoice = NULL;
BestChoices = NIL;
EnableChoiceAccum();
for (BlobWidth = CurrentSegmentation,
End = CurrentSegmentation + MAX_NUM_CHUNKS;
BlobWidth < End; *BlobWidth++ = 1);
} /* InitChoiceAccum */
/*---------------------------------------------------------------------------*/
void
LogNewRawChoice (A_CHOICE * Choice, FLOAT32 AdjustFactor, float Certainties[]) {
/*
** Parameters:
** Choice new raw choice for current word
** AdjustFactor adjustment factor which was applied to choice
** Certainties certainties for each char in new choice
** Globals:
** BestRawChoice best raw choice so far for current word
** Operation: This routine compares Choice to the best raw (non-dict)
** choice so far and replaces it if the new choice is better.
** Return: none
** Exceptions: none
** History: Wed May 15 09:57:19 1991, DSJ, Created.
*/
if (!KeepWordChoices)
return;
if (!BestRawChoice)
BestRawChoice = NewViableChoice (Choice, AdjustFactor, Certainties);
else if (class_probability (Choice) < BestRawChoice->Rating) {
if (ChoiceSameAs (Choice, BestRawChoice))
ReplaceDuplicateChoice(BestRawChoice, Choice, AdjustFactor, Certainties);
else {
memfree(BestRawChoice);
BestRawChoice = NewViableChoice (Choice, AdjustFactor, Certainties);
}
}
} /* LogNewRawChoice */
/*---------------------------------------------------------------------------*/
void LogNewSegmentation(PIECES_STATE BlobWidth) {
/*
** Parameters:
** BlobWidth[] number of chunks in each blob in segmentation
** Globals:
** CurrentSegmentation blob widths for current segmentation
** Operation: This routine updates the blob widths in CurrentSegmentation
** to be the same as provided in BlobWidth.
** Return: none
** Exceptions: none
** History: Mon May 20 11:52:26 1991, DSJ, Created.
*/
BLOB_WIDTH *Segmentation;
for (Segmentation = CurrentSegmentation; *BlobWidth != 0;
BlobWidth++, Segmentation++)
*Segmentation = *BlobWidth;
*Segmentation = 0;
} /* LogNewSegmentation */
/*---------------------------------------------------------------------------*/
void LogNewSplit(int Blob) {
/*
** Parameters:
** Blob index of blob that was split
** Globals:
** BestRawChoice current best raw choice
** BestChoices list of best choices found so far
** Operation: This routine adds 1 chunk to the specified blob for each
** choice in BestChoices and for the BestRawChoice.
** Return: none
** Exceptions: none
** History: Mon May 20 11:38:56 1991, DSJ, Created.
*/
LIST Choices;
if (BestRawChoice) {
AddNewChunk(BestRawChoice, Blob);
}
Choices = BestChoices;
iterate(Choices) {
AddNewChunk ((VIABLE_CHOICE) first (Choices), Blob);
}
} /* LogNewSplit */
/*---------------------------------------------------------------------------*/
void
LogNewWordChoice (A_CHOICE * Choice,
FLOAT32 AdjustFactor, float Certainties[]) {
/*
** Parameters:
** Choice new choice for current word
** AdjustFactor adjustment factor which was applied to choice
** Certainties certainties for each char in new choice
** Globals:
** BestChoices best choices so far for current word
** Operation: This routine adds Choice to BestChoices if the
** adjusted certainty for Choice is within a reasonable range
** of the best choice in BestChoices. The BestChoices
** list is kept in sorted order by rating. Duplicates are
** removed.
** Return: none
** Exceptions: none
** History: Wed May 15 09:57:19 1991, DSJ, Created.
*/
VIABLE_CHOICE NewChoice;
LIST Choices;
FLOAT32 Threshold;
if (!KeepWordChoices)
return;
/* throw out obviously bad choices to save some work */
if (BestChoices != NIL) {
Threshold = AmbigThreshold (BestFactor (BestChoices), AdjustFactor);
if (Threshold > -AmbigThresholdOffset)
Threshold = -AmbigThresholdOffset;
if (class_certainty (Choice) - BestCertainty (BestChoices) < Threshold)
return;
}
/* see if a choice with the same text string has already been found */
NewChoice = NULL;
Choices = BestChoices;
iterate(Choices) {
if (ChoiceSameAs (Choice, (VIABLE_CHOICE) first (Choices)))
if (class_probability (Choice) < BestRating (Choices))
NewChoice = (VIABLE_CHOICE) first (Choices);
else
return;
}
if (NewChoice) {
ReplaceDuplicateChoice(NewChoice, Choice, AdjustFactor, Certainties);
BestChoices = delete_d (BestChoices, NewChoice, is_same_node);
}
else {
NewChoice = NewViableChoice (Choice, AdjustFactor, Certainties);
}
BestChoices = s_adjoin (BestChoices, NewChoice, CmpChoiceRatings);
if (StopperDebugLevel >= 2)
PrintViableChoice (stdout, "New Word Choice: ", NewChoice);
if (count (BestChoices) > tessedit_truncate_wordchoice_log) {
Choices =
(LIST) nth_cell (BestChoices, tessedit_truncate_wordchoice_log);
destroy_nodes (rest (Choices), Efree);
set_rest(Choices, NIL);
}
} /* LogNewWordChoice */
/*---------------------------------------------------------------------------*/
static AMBIG_TABLE *AmbigFor = NULL;
int NoDangerousAmbig(const char *Word, DANGERR *fixpt) {
/*
** Parameters:
** Word word to check for dangerous ambiguities
** Globals: none
** Operation: This word checks each letter in word against a list
** of potentially ambiguous characters. If a match is found
** that letter is replaced with its ambiguity and tested in
** the dictionary. If the ambiguous word is found in the
** dictionary, FALSE is returned. Otherwise, the search
** continues for other ambiguities. If no ambiguities that
** match in the dictionary are found, TRUE is returned.
** Return: TRUE if Word contains no dangerous ambiguities.
** Exceptions: none
** History: Mon May 6 16:28:56 1991, DSJ, Created.
*/
char NewWord[MAX_WERD_SIZE];
char *NextNewChar;
int bad_index = 0;
if (!AmbigFor)
AmbigFor = FillAmbigTable ();
NextNewChar = NewWord;
while (*Word)
if (AmbigsFound (NewWord, NextNewChar, Word + 1, AmbigFor[*Word], fixpt)) {
if (fixpt != NULL)
fixpt->index = bad_index;
return (FALSE);
}
else {
*NextNewChar++ = *Word++;
bad_index++;
}
return (TRUE);
} /* NoDangerousAmbig */
void EndDangerousAmbigs() {
if (AmbigFor != NULL) {
for (int i = 0; i <= MAX_CLASS_ID; ++i) {
destroy_nodes(AmbigFor[i], Efree);
}
Efree(AmbigFor);
AmbigFor = NULL;
}
}
/*---------------------------------------------------------------------------*/
void SettupStopperPass1() {
/*
** Parameters: none
** Globals:
** RejectOffset offset allowed before word is rejected
** Operation: This routine performs any settup of stopper variables
** that is needed in preparation for the first pass.
** Return: none
** Exceptions: none
** History: Mon Jun 3 12:32:00 1991, DSJ, Created.
*/
RejectOffset = 0.0;
} /* SettupStopperPass1 */
/*---------------------------------------------------------------------------*/
void SettupStopperPass2() {
/*
** Parameters: none
** Globals:
** RejectOffset offset allowed before word is rejected
** Operation: This routine performs any settup of stopper variables
** that is needed in preparation for the second pass.
** Return: none
** Exceptions: none
** History: Mon Jun 3 12:32:00 1991, DSJ, Created.
*/
RejectOffset = RejectCertaintyOffset;
} /* SettupStopperPass2 */
/**----------------------------------------------------------------------------
Private Code
----------------------------------------------------------------------------**/
/*---------------------------------------------------------------------------*/
void AddNewChunk(VIABLE_CHOICE Choice, int Blob) {
/*
** Parameters:
** Choice choice to add a new chunk to
** Blob index of blob being split
** Globals: none
** Operation: This routine increments the chunk count of the character
** in Choice which corresponds to Blob.
** Return: none
** Exceptions: none
** History: Mon May 20 11:43:27 1991, DSJ, Created.
*/
int i, LastChunk;
for (i = 0, LastChunk = 0; i < Choice->Length; i++) {
LastChunk += Choice->Blob[i].NumChunks;
if (Blob < LastChunk) {
(Choice->Blob[i].NumChunks)++;
return;
}
}
mem_tidy (1);
cprintf ("AddNewChunk failed:Choice->Length=%d, LastChunk=%d, Blob=%d\n",
Choice->Length, LastChunk, Blob);
assert(FALSE); /* this should never get executed */
} /* AddNewChunk */
/*---------------------------------------------------------------------------*/
int AmbigsFound(char *Word,
char *CurrentChar,
const char *Tail,
LIST Ambigs,
DANGERR *fixpt) {
/*
** Parameters:
** Word word being tested for ambiguities
** CurrentChar position in Word to put ambig replacement
** Tail end of word to place after ambiguity
** Ambigs list of ambiguities to test at this position
** Globals: none
** Operation: For each ambiguity in Ambigs, see if the remainder of
** the test string matches the start of Tail. If it does,
** construct a word consisting of the contents of Word up to,
** but not including, CurrentChar followed by the replacement
** string for the ambiguity followed by the unmatched
** contents of Tail. Then test this word to see if it
** is a dictionary word. If it is return TRUE. If none of
** the ambiguities result in a dictionary word, return FALSE.
** Return: TRUE if the Word is ambiguous at the specified position
** Exceptions: none
** History: Thu May 9 10:10:28 1991, DSJ, Created.
*/
char *AmbigSpec;
const char *UnmatchedTail;
int Matches;
int bad_length;
iterate(Ambigs) {
AmbigSpec = (char *) first (Ambigs);
bad_length = 1;
UnmatchedTail = Tail;
Matches = TRUE;
while (*AmbigSpec != ' ' && Matches)
if (*AmbigSpec == *UnmatchedTail) {
AmbigSpec++;
UnmatchedTail++;
bad_length++;
}
else
Matches = FALSE;
if (Matches) {
AmbigSpec++; /* skip over the space */
/* insert replacement string */
strcpy(CurrentChar, AmbigSpec);
/* add tail */
strcat(Word, UnmatchedTail);
if (valid_word (Word)) {
if (StopperDebugLevel >= 1)
cprintf ("Stopper: Possible ambiguous word = %s\n", Word);
if (fixpt != NULL) {
fixpt->good_length = strlen (AmbigSpec);
fixpt->bad_length = bad_length;
}
return (TRUE);
}
}
}
return (FALSE);
} /* AmbigsFound */
/*---------------------------------------------------------------------------*/
int ChoiceSameAs(A_CHOICE *Choice, VIABLE_CHOICE ViableChoice) {
/*
** Parameters:
** Choice choice to compare to ViableChoice
** ViableChoice viable choice to compare to Choice
** Globals: none
** Operation: This routine compares the corresponding strings of
** Choice and ViableChoice and returns TRUE if they are the
** same, FALSE otherwise.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Fri May 17 08:48:04 1991, DSJ, Created.
*/
return (StringSameAs (class_string (Choice), ViableChoice));
} /* ChoiceSameAs */
/*---------------------------------------------------------------------------*/
int CmpChoiceRatings(void *arg1, //VIABLE_CHOICE Choice1,
void *arg2) { //VIABLE_CHOICE Choice2)
/*
** Parameters:
** Choice1, Choice2 choices to compare ratings for
** Globals: none
** Operation: Return -1 if the rating for Choice1 is less than the
** rating for Choice2, otherwise return (1).
** Return: -1 or 1
** Exceptions: none
** History: Wed May 15 13:02:37 1991, DSJ, Created.
*/
float R1, R2;
VIABLE_CHOICE Choice1 = (VIABLE_CHOICE) arg1;
VIABLE_CHOICE Choice2 = (VIABLE_CHOICE) arg2;
R1 = Choice1->Rating;
R2 = Choice2->Rating;
if (R1 < R2)
return (-1);
else
return (1);
} /* CmpChoiceRatings */
/*---------------------------------------------------------------------------*/
void ExpandChoice(VIABLE_CHOICE Choice, EXPANDED_CHOICE *ExpandedChoice) {
/*
** Parameters:
** Choice choice to be expanded
** ExpandedChoice place to put resulting expanded choice
** Globals: none
** Operation: This routine expands Choice and places the results
** in ExpandedChoice. The primary function of expansion
** is to create an two arrays, one which holds the corresponding
** certainty for each chunk in Choice, and one which holds
** the class for each chunk.
** Return: none (results are placed in ExpandedChoice)
** Exceptions: none
** History: Fri May 31 15:21:57 1991, DSJ, Created.
*/
int i, j, Chunk;
ExpandedChoice->Choice = Choice;
for (i = 0, Chunk = 0; i < Choice->Length; i++)
for (j = 0; j < Choice->Blob[i].NumChunks; j++, Chunk++) {
ExpandedChoice->ChunkCertainty[Chunk] = Choice->Blob[i].Certainty;
ExpandedChoice->ChunkClass[Chunk] = Choice->Blob[i].Class;
}
} /* ExpandChoice */
/*---------------------------------------------------------------------------*/
AMBIG_TABLE *FillAmbigTable() {
/*
** Parameters: none
** Globals:
** DangerousAmbigs filename of dangerous ambig info
** Operation: This routine allocates a new ambiguity table and fills
** it in from the file specified by DangerousAmbigs. An
** ambiguity table is an array of lists. The array is indexed
** by a class id. Therefore, each entry in the table provides
** a list of potential ambiguities which can start with the
** corresponding character. Each potential ambiguity is
** described by a string which contains the remainder of the
** test string followed by a space followed by the replacement
** string. For example the ambiguity "rn -> m", would be
** located in the table at index 'r'. The string corresponding
** to this ambiguity would be "n m".
** Return: Pointer to new ambiguity table.
** Exceptions: none
** History: Thu May 9 09:20:57 1991, DSJ, Created.
*/
FILE *AmbigFile;
AMBIG_TABLE *NewTable;
int i;
char TestString[256];
char ReplacementString[256];
char name[1024];
char *AmbigSpec;
int AmbigSize;
strcpy(name, demodir);
strcat(name, DangerousAmbigs);
AmbigFile = Efopen (name, "r");
NewTable = (AMBIG_TABLE *) Emalloc (sizeof (LIST) * (MAX_CLASS_ID + 1));
for (i = 0; i <= MAX_CLASS_ID; i++)
NewTable[i] = NIL;
while (fscanf (AmbigFile, "%s", TestString) == 1 &&
fscanf (AmbigFile, "%s", ReplacementString) == 1) {
if (strlen (TestString) > MAX_AMBIG_SIZE ||
strlen (ReplacementString) > MAX_AMBIG_SIZE)
DoError (0, "Illegal ambiguity specification!");
AmbigSize = strlen (TestString) + strlen (ReplacementString) + 1;
AmbigSpec = (char *) Emalloc (sizeof (char) * AmbigSize);
strcpy (AmbigSpec, &(TestString[1]));
strcat (AmbigSpec, " ");
strcat(AmbigSpec, ReplacementString);
NewTable[TestString[0]] =
push_last (NewTable[TestString[0]], AmbigSpec);
}
fclose(AmbigFile);
return (NewTable);
} /* FillAmbigTable */
/*---------------------------------------------------------------------------*/
int FreeBadChoice(void *item1, //VIABLE_CHOICE Choice,
void *item2) { //EXPANDED_CHOICE *BestChoice)
/*
** Parameters:
** Choice choice to be tested
** BestChoice best choice found
** Globals:
** AmbigThresholdGain
** AmbigThresholdOffset
** Operation: If the certainty of any chunk in Choice is not ambiguous
** with the corresponding chunk in the best choice, free
** Choice and return TRUE. Otherwise, return FALSE.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Wed May 15 13:20:26 1991, DSJ, Created.
*/
int i, j, Chunk;
FLOAT32 Threshold;
VIABLE_CHOICE Choice;
EXPANDED_CHOICE *BestChoice;
Choice = (VIABLE_CHOICE) item1;
BestChoice = (EXPANDED_CHOICE *) item2;
Threshold = AmbigThreshold (BestChoice->Choice->AdjustFactor,
Choice->AdjustFactor);
for (i = 0, Chunk = 0; i < Choice->Length; i++)
for (j = 0; j < Choice->Blob[i].NumChunks; j++, Chunk++)
if (Choice->Blob[i].Class != BestChoice->ChunkClass[Chunk] &&
Choice->Blob[i].Certainty - BestChoice->ChunkCertainty[Chunk] <
Threshold) {
memfree(Choice);
return (TRUE);
}
return (FALSE);
} /* FreeBadChoice */
/*---------------------------------------------------------------------------*/
int LengthOfShortestAlphaRun(register char *Word) {
/*
** Parameters:
** Word word to be tested
** Globals: none
** Operation: Return the length of the shortest alpha run in Word.
** Return: Return the length of the shortest alpha run in Word.
** Exceptions: none
** History: Tue May 14 07:50:45 1991, DSJ, Created.
*/
register int Shortest = MAXINT;
register int Length;
for (; *Word; Word++)
if (isalpha (*Word)) {
for (Length = 1, Word++; isalpha (*Word); Word++, Length++);
if (Length < Shortest)
Shortest = Length;
if (*Word == 0)
break;
}
if (Shortest == MAXINT)
Shortest = 0;
return (Shortest);
} /* LengthOfShortestAlphaRun */
/*---------------------------------------------------------------------------*/
VIABLE_CHOICE
NewViableChoice (A_CHOICE * Choice, FLOAT32 AdjustFactor, float Certainties[]) {
/*
** Parameters:
** Choice choice to be converted to a viable choice
** AdjustFactor factor used to adjust ratings for Choice
** Certainties certainty for each character in Choice
** Globals:
** CurrentSegmentation segmentation corresponding to Choice
** Operation: Allocate a new viable choice data structure, copy
** Choice, Certainties, and CurrentSegmentation into it,
** and return a pointer to it.
** Return: Ptr to new viable choice.
** Exceptions: none
** History: Thu May 16 15:28:29 1991, DSJ, Created.
*/
VIABLE_CHOICE NewChoice;
int Length;
char *Word;
CHAR_CHOICE *NewChar;
BLOB_WIDTH *BlobWidth;
Length = strlen (class_string (Choice));
assert (Length <= MAX_NUM_CHUNKS && Length > 0);
NewChoice = (VIABLE_CHOICE) Emalloc (sizeof (VIABLE_CHOICE_STRUCT) +
(Length - 1) * sizeof (CHAR_CHOICE));
NewChoice->Rating = class_probability (Choice);
NewChoice->Certainty = class_certainty (Choice);
NewChoice->AdjustFactor = AdjustFactor;
NewChoice->Length = Length;
for (Word = class_string (Choice),
NewChar = &(NewChoice->Blob[0]),
BlobWidth = CurrentSegmentation;
*Word; Word++, NewChar++, Certainties++, BlobWidth++) {
NewChar->Class = *Word;
NewChar->NumChunks = *BlobWidth;
NewChar->Certainty = *Certainties;
}
return (NewChoice);
} /* NewViableChoice */
/*---------------------------------------------------------------------------*/
void PrintViableChoice(FILE *File, const char *Label, VIABLE_CHOICE Choice) {
/*
** Parameters:
** File open text file to print Choice to
** Label text label to be printed with Choice
** Choice choice to be printed
** Globals: none
** Operation: This routine dumps a text representation of the
** specified Choice to File.
** Return: none
** Exceptions: none
** History: Mon May 20 11:16:44 1991, DSJ, Created.
*/
int i, j;
fprintf (File, "%s", Label);
fprintf (File, "(R=%5.1f, C=%4.1f, F=%4.2f) ",
Choice->Rating, Choice->Certainty, Choice->AdjustFactor);
for (i = 0; i < Choice->Length; i++)
fprintf (File, "%c", Choice->Blob[i].Class);
fprintf (File, "\n");
for (i = 0; i < Choice->Length; i++) {
fprintf (File, " %c", Choice->Blob[i].Class);
for (j = 0; j < Choice->Blob[i].NumChunks - 1; j++)
fprintf (File, " ");
}
fprintf (File, "\n");
for (i = 0; i < Choice->Length; i++) {
for (j = 0; j < Choice->Blob[i].NumChunks; j++)
fprintf (File, "%3d", (int) (Choice->Blob[i].Certainty * -10.0));
}
fprintf (File, "\n");
} /* PrintViableChoice */
/*---------------------------------------------------------------------------*/
void
ReplaceDuplicateChoice (VIABLE_CHOICE OldChoice,
A_CHOICE * NewChoice,
FLOAT32 AdjustFactor, float Certainties[]) {
/*
** Parameters:
** OldChoice existing viable choice to be replaced
** NewChoice choice to replace OldChoice with
** AdjustFactor factor used to adjust ratings for OldChoice
** Certainties certainty for each character in OldChoice
** Globals:
** CurrentSegmentation segmentation for NewChoice
** Operation: This routine is used whenever a better segmentation (or
** contextual interpretation) is found for a word which already
** exists. The OldChoice is updated with the relevant
** information from the new choice. The text string itself
** does not need to be copied since, by definition, has not
** changed.
** Return: none
** Exceptions: none
** History: Fri May 17 13:35:58 1991, DSJ, Created.
*/
char *Word;
CHAR_CHOICE *NewChar;
BLOB_WIDTH *BlobWidth;
OldChoice->Rating = class_probability (NewChoice);
OldChoice->Certainty = class_certainty (NewChoice);
OldChoice->AdjustFactor = AdjustFactor;
for (Word = class_string (NewChoice),
NewChar = &(OldChoice->Blob[0]),
BlobWidth = CurrentSegmentation;
*Word; Word++, NewChar++, Certainties++, BlobWidth++) {
NewChar->NumChunks = *BlobWidth;
NewChar->Certainty = *Certainties;
}
} /* ReplaceDuplicateChoice */
/*---------------------------------------------------------------------------*/
int StringSameAs(const char *String, VIABLE_CHOICE ViableChoice) {
/*
** Parameters:
** String string to compare to ViableChoice
** ViableChoice viable choice to compare to String
** Globals: none
** Operation: This routine compares String to ViableChoice and
** returns TRUE if they are the same, FALSE otherwise.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Fri May 17 08:48:04 1991, DSJ, Created.
*/
CHAR_CHOICE *Char;
int i;
for (Char = &(ViableChoice->Blob[0]), i = 0;
i < ViableChoice->Length; String++, Char++, i++)
if (*String != Char->Class)
return (FALSE);
if (*String == 0)
return (TRUE);
else
return (FALSE);
} /* StringSameAs */
/*---------------------------------------------------------------------------*/
int UniformCertainties(CHOICES_LIST Choices, A_CHOICE *BestChoice) {
/*
** Parameters:
** Choices choices for current segmentation
** BestChoice best choice for current segmentation
** Globals:
** CertaintyVariation max allowed certainty variation
** Operation: This routine returns TRUE if the certainty of the
** BestChoice word is within a reasonable range of the average
** certainties for the best choices for each character in
** the segmentation. This test is used to catch words in which
** one character is much worse than the other characters in
** the word (i.e. FALSE will be returned in that case).
** The algorithm computes the mean and std deviation of the
** certainties in the word with the worst certainty thrown out.
** Return: TRUE or FALSE.
** Exceptions: none
** History: Tue May 14 08:23:21 1991, DSJ, Created.
*/
int i;
CHOICES CharChoices;
float Certainty;
float WorstCertainty = MAX_FLOAT32;
float CertaintyThreshold;
FLOAT64 TotalCertainty;
FLOAT64 TotalCertaintySquared;
FLOAT64 Variance;
FLOAT32 Mean, StdDev;
int WordLength;
WordLength = array_count (Choices);
if (WordLength < 3)
return (TRUE);
TotalCertainty = TotalCertaintySquared = 0.0;
for_each_choice(Choices, i) {
CharChoices = (CHOICES) array_index (Choices, i);
Certainty = best_certainty (CharChoices);
TotalCertainty += Certainty;
TotalCertaintySquared += Certainty * Certainty;
if (Certainty < WorstCertainty)
WorstCertainty = Certainty;
}
/* subtract off worst certainty from statistics */
WordLength--;
TotalCertainty -= WorstCertainty;
TotalCertaintySquared -= WorstCertainty * WorstCertainty;
Mean = TotalCertainty / WordLength;
Variance = ((WordLength * TotalCertaintySquared -
TotalCertainty * TotalCertainty) /
(WordLength * (WordLength - 1)));
if (Variance < 0.0)
Variance = 0.0;
StdDev = sqrt (Variance);
CertaintyThreshold = Mean - CertaintyVariation * StdDev;
if (CertaintyThreshold > NonDictCertainty)
CertaintyThreshold = NonDictCertainty;
if (class_certainty (BestChoice) < CertaintyThreshold) {
if (StopperDebugLevel >= 1)
cprintf
("Stopper: Non-uniform certainty = %4.1f (m=%4.1f, s=%4.1f, t=%4.1f)\n",
class_certainty (BestChoice), Mean, StdDev, CertaintyThreshold);
return (FALSE);
}
else
return (TRUE);
} /* UniformCertainties */
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