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mteval-v11b_sbp.pl
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mteval-v11b_sbp.pl
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#!/usr/bin/perl -w
use strict;
#################################
# History:
#
# version 11b -- text normalization modified:
# * take out the join digit line because it joins digits
# when it shouldn't have
# $norm_text =~ s/(\d)\s+(?=\d)/$1/g; #join digits
#
# version 11a -- corrected output of individual n-gram precision values
#
# version 11 -- bug fixes:
# * make filehandle operate in binary mode to prevent Perl from operating
# (by default in Red Hat 9) in UTF-8
# * fix failure on joining digits
# version 10 -- updated output to include more details of n-gram scoring.
# Defaults to generate both NIST and BLEU scores. Use -b for BLEU
# only, use -n for NIST only
#
# version 09d -- bug fix (for BLEU scoring, ngrams were fixed at 4
# being the max, regardless what was entered on the command line.)
#
# version 09c -- bug fix (During the calculation of ngram information,
# each ngram was being counted only once for each segment. This has
# been fixed so that each ngram is counted correctly in each segment.)
#
# version 09b -- text normalization modified:
# * option flag added to preserve upper case
# * non-ASCII characters left in place.
#
# version 09a -- text normalization modified:
# * " and & converted to "" and &, respectively
# * non-ASCII characters kept together (bug fix)
#
# version 09 -- modified to accommodate sgml tag and attribute
# names revised to conform to default SGML conventions.
#
# version 08 -- modifies the NIST metric in accordance with the
# findings on the 2001 Chinese-English dry run corpus. Also
# incorporates the BLEU metric as an option and supports the
# output of ngram detail.
#
# version 07 -- in response to the MT meeting on 28 Jan 2002 at ISI
# Keep strings of non-ASCII characters together as one word
# (rather than splitting them into one-character words).
# Change length penalty so that translations that are longer than
# the average reference translation are not penalized.
#
# version 06
# Prevent divide-by-zero when a segment has no evaluation N-grams.
# Correct segment index for level 3 debug output.
#
# version 05
# improve diagnostic error messages
#
# version 04
# tag segments
#
# version 03
# add detailed output option (intermediate document and segment scores)
#
# version 02
# accommodation of modified sgml tags and attributes
#
# version 01
# same as bleu version 15, but modified to provide formal score output.
#
# original IBM version
# Author: Kishore Papineni
# Date: 06/10/2001
#################################
######
# Intro
my ($date, $time) = date_time_stamp();
print "MT evaluation scorer began on $date at $time\n";
print "command line: ", $0, " ", join(" ", @ARGV), "\n";
my $usage = "\n\nUsage: $0 [-h] -r <ref_file> -s src_file -t <tst_file>\n\n".
"Description: This Perl script evaluates MT system performance.\n".
"\n".
"Required arguments:\n".
" -r <ref_file> is a file containing the reference translations for\n".
" the documents to be evaluated.\n".
" -s <src_file> is a file containing the source documents for which\n".
" translations are to be evaluated\n".
" -t <tst_file> is a file containing the translations to be evaluated\n".
"\n".
"Optional arguments:\n".
" -c preserves upper-case alphabetic characters\n".
" -b generate BLEU scores only\n".
" -n generate NIST scores only\n".
" -d detailed output flag used in conjunction with \"-b\" or \"-n\" flags:\n".
" 0 (default) for system-level score only\n".
" 1 to include document-level scores\n".
" 2 to include segment-level scores\n".
" 3 to include ngram-level scores\n".
" -h prints this help message to STDOUT\n".
"\n";
use vars qw ($opt_r $opt_s $opt_t $opt_d $opt_h $opt_b $opt_n $opt_c $opt_x);
use Getopt::Std;
getopts ('r:s:t:d:hbncx:');
die $usage if defined($opt_h);
die "Error in command line: ref_file not defined$usage" unless defined $opt_r;
die "Error in command line: src_file not defined$usage" unless defined $opt_s;
die "Error in command line: tst_file not defined$usage" unless defined $opt_t;
my $max_Ngram = 9;
my $detail = defined $opt_d ? $opt_d : 0;
my $preserve_case = defined $opt_c ? 1 : 0;
my $METHOD = "BOTH";
if (defined $opt_b) { $METHOD = "BLEU"; }
if (defined $opt_n) { $METHOD = "NIST"; }
my $method;
my ($ref_file) = $opt_r;
my ($src_file) = $opt_s;
my ($tst_file) = $opt_t;
######
# Global variables
my ($src_lang, $tgt_lang, @tst_sys, @ref_sys); # evaluation parameters
my (%tst_data, %ref_data); # the data -- with structure: {system}{document}[segments]
my ($src_id, $ref_id, $tst_id); # unique identifiers for ref and tst translation sets
my %eval_docs; # document information for the evaluation data set
my %ngram_info; # the information obtained from (the last word in) the ngram
######
# Get source document ID's
($src_id) = get_source_info ($src_file);
######
# Get reference translations
($ref_id) = get_MT_data (\%ref_data, "RefSet", $ref_file);
compute_ngram_info ();
######
# Get translations to evaluate
($tst_id) = get_MT_data (\%tst_data, "TstSet", $tst_file);
######
# Check data for completeness and correctness
check_MT_data ();
######
#
my %NISTmt = ();
my %BLEUmt = ();
######
# Evaluate
print " Evaluation of $src_lang-to-$tgt_lang translation using:\n";
my $cum_seg = 0;
foreach my $doc (sort keys %eval_docs) {
$cum_seg += @{$eval_docs{$doc}{SEGS}};
}
print " src set \"$src_id\" (", scalar keys %eval_docs, " docs, $cum_seg segs)\n";
print " ref set \"$ref_id\" (", scalar keys %ref_data, " refs)\n";
print " tst set \"$tst_id\" (", scalar keys %tst_data, " systems)\n\n";
foreach my $sys (sort @tst_sys) {
for (my $n=1; $n<=$max_Ngram; $n++) {
$NISTmt{$n}{$sys}{cum} = 0;
$NISTmt{$n}{$sys}{ind} = 0;
$BLEUmt{$n}{$sys}{cum} = 0;
$BLEUmt{$n}{$sys}{ind} = 0;
}
if (($METHOD eq "BOTH") || ($METHOD eq "NIST")) {
$method="NIST";
score_system ($sys, %NISTmt);
}
if (($METHOD eq "BOTH") || ($METHOD eq "BLEU")) {
$method="BLEU";
score_system ($sys, %BLEUmt);
}
}
######
printout_report ();
($date, $time) = date_time_stamp();
print "MT evaluation scorer ended on $date at $time\n";
exit 0;
#################################
sub get_source_info {
my ($file) = @_;
my ($name, $id, $src, $doc);
my ($data, $tag, $span);
#read data from file
open (FILE, $file) or die "\nUnable to open translation data file '$file'", $usage;
binmode FILE;
$data .= $_ while <FILE>;
close (FILE);
#get source set info
die "\n\nFATAL INPUT ERROR: no 'src_set' tag in src_file '$file'\n\n"
unless ($tag, $span, $data) = extract_sgml_tag_and_span ("SrcSet", $data);
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n"
unless ($id) = extract_sgml_tag_attribute ($name="SetID", $tag);
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n"
unless ($src) = extract_sgml_tag_attribute ($name="SrcLang", $tag);
die "\n\nFATAL INPUT ERROR: $name ('$src') in file '$file' inconsistent\n"
." with $name in previous input data ('$src_lang')\n\n"
unless (not defined $src_lang or $src eq $src_lang);
$src_lang = $src;
#get doc info -- ID and # of segs
$data = $span;
while (($tag, $span, $data) = extract_sgml_tag_and_span ("Doc", $data)) {
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n"
unless ($doc) = extract_sgml_tag_attribute ($name="DocID", $tag);
die "\n\nFATAL INPUT ERROR: duplicate '$name' in file '$file'\n\n"
if defined $eval_docs{$doc};
$span =~ s/[\s\n\r]+/ /g; # concatenate records
my $jseg=0, my $seg_data = $span;
while (($tag, $span, $seg_data) = extract_sgml_tag_and_span ("Seg", $seg_data)) {
($eval_docs{$doc}{SEGS}[$jseg++]) = NormalizeText ($span);
}
die "\n\nFATAL INPUT ERROR: no segments in document '$doc' in file '$file'\n\n"
if $jseg == 0;
}
die "\n\nFATAL INPUT ERROR: no documents in file '$file'\n\n"
unless keys %eval_docs > 0;
return $id;
}
#################################
sub get_MT_data {
my ($docs, $set_tag, $file) = @_;
my ($name, $id, $src, $tgt, $sys, $doc);
my ($tag, $span, $data);
#read data from file
open (FILE, $file) or die "\nUnable to open translation data file '$file'", $usage;
binmode FILE;
$data .= $_ while <FILE>;
close (FILE);
#get tag info
while (($tag, $span, $data) = extract_sgml_tag_and_span ($set_tag, $data)) {
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n" unless
($id) = extract_sgml_tag_attribute ($name="SetID", $tag);
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n" unless
($src) = extract_sgml_tag_attribute ($name="SrcLang", $tag);
die "\n\nFATAL INPUT ERROR: $name ('$src') in file '$file' inconsistent\n"
." with $name of source ('$src_lang')\n\n"
unless $src eq $src_lang;
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n" unless
($tgt) = extract_sgml_tag_attribute ($name="TrgLang", $tag);
die "\n\nFATAL INPUT ERROR: $name ('$tgt') in file '$file' inconsistent\n"
." with $name of the evaluation ('$tgt_lang')\n\n"
unless (not defined $tgt_lang or $tgt eq $tgt_lang);
$tgt_lang = $tgt;
my $mtdata = $span;
while (($tag, $span, $mtdata) = extract_sgml_tag_and_span ("Doc", $mtdata)) {
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n" unless
(my $sys) = extract_sgml_tag_attribute ($name="SysID", $tag);
die "\n\nFATAL INPUT ERROR: no tag attribute '$name' in file '$file'\n\n" unless
$doc = extract_sgml_tag_attribute ($name="DocID", $tag);
die "\n\nFATAL INPUT ERROR: document '$doc' for system '$sys' in file '$file'\n"
." previously loaded from file '$docs->{$sys}{$doc}{FILE}'\n\n"
unless (not defined $docs->{$sys}{$doc});
$span =~ s/[\s\n\r]+/ /g; # concatenate records
my $jseg=0, my $seg_data = $span;
while (($tag, $span, $seg_data) = extract_sgml_tag_and_span ("Seg", $seg_data)) {
($docs->{$sys}{$doc}{SEGS}[$jseg++]) = NormalizeText ($span);
}
die "\n\nFATAL INPUT ERROR: no segments in document '$doc' in file '$file'\n\n"
if $jseg == 0;
$docs->{$sys}{$doc}{FILE} = $file;
}
}
return $id;
}
#################################
sub check_MT_data {
@tst_sys = sort keys %tst_data;
@ref_sys = sort keys %ref_data;
#every evaluation document must be represented for every system and every reference
foreach my $doc (sort keys %eval_docs) {
my $nseg_source = @{$eval_docs{$doc}{SEGS}};
foreach my $sys (@tst_sys) {
die "\n\nFATAL ERROR: no document '$doc' for system '$sys'\n\n"
unless defined $tst_data{$sys}{$doc};
my $nseg = @{$tst_data{$sys}{$doc}{SEGS}};
die "\n\nFATAL ERROR: translated documents must contain the same # of segments as the source, but\n"
." document '$doc' for system '$sys' contains $nseg segments, while\n"
." the source document contains $nseg_source segments.\n\n"
unless $nseg == $nseg_source;
}
foreach my $sys (@ref_sys) {
die "\n\nFATAL ERROR: no document '$doc' for reference '$sys'\n\n"
unless defined $ref_data{$sys}{$doc};
my $nseg = @{$ref_data{$sys}{$doc}{SEGS}};
die "\n\nFATAL ERROR: translated documents must contain the same # of segments as the source, but\n"
." document '$doc' for system '$sys' contains $nseg segments, while\n"
." the source document contains $nseg_source segments.\n\n"
unless $nseg == $nseg_source;
}
}
}
#################################
sub compute_ngram_info {
my ($ref, $doc, $seg);
my (@wrds, $tot_wrds, %ngrams, $ngram, $mgram);
my (%ngram_count, @tot_ngrams);
foreach $ref (keys %ref_data) {
foreach $doc (keys %{$ref_data{$ref}}) {
foreach $seg (@{$ref_data{$ref}{$doc}{SEGS}}) {
@wrds = split /\s+/, $seg;
$tot_wrds += @wrds;
%ngrams = %{Words2Ngrams (@wrds)};
foreach $ngram (keys %ngrams) {
$ngram_count{$ngram} += $ngrams{$ngram};
}
}
}
}
foreach $ngram (keys %ngram_count) {
@wrds = split / /, $ngram;
pop @wrds, $mgram = join " ", @wrds;
$ngram_info{$ngram} = - log
($mgram ? $ngram_count{$ngram}/$ngram_count{$mgram}
: $ngram_count{$ngram}/$tot_wrds) / log 2;
if (defined $opt_x and $opt_x eq "ngram info") {
@wrds = split / /, $ngram;
printf "ngram info:%9.4f%6d%6d%8d%3d %s\n", $ngram_info{$ngram}, $ngram_count{$ngram},
$mgram ? $ngram_count{$mgram} : $tot_wrds, $tot_wrds, scalar @wrds, $ngram;
}
}
}
#################################
sub score_system {
my ($sys, $ref, $doc, %SCOREmt);
($sys, %SCOREmt) = @_;
my ($shortest_ref_length, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info);
my ($cum_ref_length, @cum_match, @cum_tst_cnt, @cum_ref_cnt, @cum_tst_info, @cum_ref_info);
my ($doc_min_tst_ref_length, $sys_min_tst_ref_length) = (0,0);
$cum_ref_length = 0;
for (my $j=1; $j<=$max_Ngram; $j++) {
$cum_match[$j] = $cum_tst_cnt[$j] = $cum_ref_cnt[$j] = $cum_tst_info[$j] = $cum_ref_info[$j] = 0;
}
foreach $doc (sort keys %eval_docs) {
($shortest_ref_length, $doc_min_tst_ref_length, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info) = score_document ($sys, $doc);
#output document summary score
if (($detail >= 1 ) && ($METHOD eq "NIST")) {
my %DOCmt = ();
printf "$method score using 5-grams = %.4f for system \"$sys\" on document \"$doc\" (%d segments, %d words)\n",
nist_score (scalar @ref_sys, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info, $sys, %DOCmt),
scalar @{$tst_data{$sys}{$doc}{SEGS}}, $tst_cnt->[1];
}
if (($detail >= 1 ) && ($METHOD eq "BLEU")) {
my %DOCmt = ();
printf "$method score using 4-grams = %.4f for system \"$sys\" on document \"$doc\" (%d segments, %d words)\n",
bleu_score($shortest_ref_length, $doc_min_tst_ref_length, $match_cnt, $tst_cnt, $sys, %DOCmt),
scalar @{$tst_data{$sys}{$doc}{SEGS}}, $tst_cnt->[1];
}
$sys_min_tst_ref_length += $doc_min_tst_ref_length;
$cum_ref_length += $shortest_ref_length;
for (my $j=1; $j<=$max_Ngram; $j++) {
$cum_match[$j] += $match_cnt->[$j];
$cum_tst_cnt[$j] += $tst_cnt->[$j];
$cum_ref_cnt[$j] += $ref_cnt->[$j];
$cum_tst_info[$j] += $tst_info->[$j];
$cum_ref_info[$j] += $ref_info->[$j];
printf "document info: $sys $doc %d-gram %d %d %d %9.4f %9.4f\n", $j, $match_cnt->[$j],
$tst_cnt->[$j], $ref_cnt->[$j], $tst_info->[$j], $ref_info->[$j]
if (defined $opt_x and $opt_x eq "document info");
}
}
#x #output system summary score
#x printf "$method score = %.4f for system \"$sys\"\n",
#x $method eq "BLEU" ? bleu_score($cum_ref_length, \@cum_match, \@cum_tst_cnt) :
#x nist_score (scalar @ref_sys, \@cum_match, \@cum_tst_cnt, \@cum_ref_cnt, \@cum_tst_info, \@cum_ref_info, $sys, %SCOREmt);
if ($method eq "BLEU") {
bleu_score($cum_ref_length, $sys_min_tst_ref_length, \@cum_match, \@cum_tst_cnt, $sys, %SCOREmt);
}
if ($method eq "NIST") {
nist_score (scalar @ref_sys, \@cum_match, \@cum_tst_cnt, \@cum_ref_cnt, \@cum_tst_info, \@cum_ref_info, $sys, %SCOREmt);
}
}
#################################
sub score_document {
my ($sys, $ref, $doc);
($sys, $doc) = @_;
my ($shortest_ref_length, $seg_min_tst_ref_length, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info);
my ($cum_ref_length, $doc_min_tst_ref_length, @cum_match, @cum_tst_cnt, @cum_ref_cnt, @cum_tst_info, @cum_ref_info);
$cum_ref_length = 0;
for (my $j=1; $j<=$max_Ngram; $j++) {
$cum_match[$j] = $cum_tst_cnt[$j] = $cum_ref_cnt[$j] = $cum_tst_info[$j] = $cum_ref_info[$j] = 0;
}
#score each segment
for (my $jseg=0; $jseg<@{$tst_data{$sys}{$doc}{SEGS}}; $jseg++) {
my @ref_segments = ();
foreach $ref (@ref_sys) {
push @ref_segments, $ref_data{$ref}{$doc}{SEGS}[$jseg];
printf "ref '$ref', seg %d: %s\n", $jseg+1, $ref_data{$ref}{$doc}{SEGS}[$jseg]
if $detail >= 3;
}
printf "sys '$sys', seg %d: %s\n", $jseg+1, $tst_data{$sys}{$doc}{SEGS}[$jseg]
if $detail >= 3;
($shortest_ref_length, $seg_min_tst_ref_length, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info) =
score_segment ($tst_data{$sys}{$doc}{SEGS}[$jseg], @ref_segments);
#output segment summary score
#x printf "$method score = %.4f for system \"$sys\" on segment %d of document \"$doc\" (%d words)\n",
#x $method eq "BLEU" ? bleu_score($shortest_ref_length, $match_cnt, $tst_cnt) :
#x nist_score (scalar @ref_sys, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info),
#x $jseg+1, $tst_cnt->[1]
#x if $detail >= 2;
if (($detail >=2) && ($METHOD eq "BLEU")) {
my %DOCmt = ();
printf " $method score using 4-grams = %.4f for system \"$sys\" on segment %d of document \"$doc\" (%d words)\n",
bleu_score($shortest_ref_length, $seg_min_tst_ref_length, $match_cnt, $tst_cnt, $sys, %DOCmt), $jseg+1, $tst_cnt->[1];
}
if (($detail >=2) && ($METHOD eq "NIST")) {
my %DOCmt = ();
printf " $method score using 5-grams = %.4f for system \"$sys\" on segment %d of document \"$doc\" (%d words)\n",
nist_score (scalar @ref_sys, $match_cnt, $tst_cnt, $ref_cnt, $tst_info, $ref_info, $sys, %DOCmt), $jseg+1, $tst_cnt->[1];
}
$doc_min_tst_ref_length += $seg_min_tst_ref_length;
$cum_ref_length += $shortest_ref_length;
for (my $j=1; $j<=$max_Ngram; $j++) {
$cum_match[$j] += $match_cnt->[$j];
$cum_tst_cnt[$j] += $tst_cnt->[$j];
$cum_ref_cnt[$j] += $ref_cnt->[$j];
$cum_tst_info[$j] += $tst_info->[$j];
$cum_ref_info[$j] += $ref_info->[$j];
}
print "doc: $seg_min_tst_ref_length cum: $doc_min_tst_ref_length \n";
}
return ($cum_ref_length, $doc_min_tst_ref_length, [@cum_match], [@cum_tst_cnt], [@cum_ref_cnt], [@cum_tst_info], [@cum_ref_info]);
}
#################################
sub score_segment {
my ($tst_seg, @ref_segs) = @_;
my (@tst_wrds, %tst_ngrams, @match_count, @tst_count, @tst_info);
my (@ref_wrds, $ref_seg, %ref_ngrams, %ref_ngrams_max, @ref_count, @ref_info);
my ($ngram);
my (@nwrds_ref);
my $shortest_ref_length;
my $min_tst_ref_length;
for (my $j=1; $j<= $max_Ngram; $j++) {
$match_count[$j] = $tst_count[$j] = $ref_count[$j] = $tst_info[$j] = $ref_info[$j] = 0;
}
# get the ngram counts for the test segment
@tst_wrds = split /\s+/, $tst_seg;
%tst_ngrams = %{Words2Ngrams (@tst_wrds)};
for (my $j=1; $j<=$max_Ngram; $j++) { # compute ngram counts
$tst_count[$j] = $j<=@tst_wrds ? (@tst_wrds - $j + 1) : 0;
}
print scalar @tst_wrds;
print " ";
# get the ngram counts for the reference segments
foreach $ref_seg (@ref_segs) {
@ref_wrds = split /\s+/, $ref_seg;
%ref_ngrams = %{Words2Ngrams (@ref_wrds)};
foreach $ngram (keys %ref_ngrams) { # find the maximum # of occurrences
my @wrds = split / /, $ngram;
$ref_info[@wrds] += $ngram_info{$ngram};
$ref_ngrams_max{$ngram} = defined $ref_ngrams_max{$ngram} ?
max ($ref_ngrams_max{$ngram}, $ref_ngrams{$ngram}) :
$ref_ngrams{$ngram};
}
for (my $j=1; $j<=$max_Ngram; $j++) { # update ngram counts
$ref_count[$j] += $j<=@ref_wrds ? (@ref_wrds - $j + 1) : 0;
}
print scalar @ref_wrds;
print " ";
$shortest_ref_length = scalar @ref_wrds # find the shortest reference segment
if (not defined $shortest_ref_length) or @ref_wrds < $shortest_ref_length;
}
# accumulate scoring stats for tst_seg ngrams that match ref_seg ngrams
foreach $ngram (keys %tst_ngrams) {
next unless defined $ref_ngrams_max{$ngram};
my @wrds = split / /, $ngram;
$tst_info[@wrds] += $ngram_info{$ngram} * min($tst_ngrams{$ngram},$ref_ngrams_max{$ngram});
$match_count[@wrds] += my $count = min($tst_ngrams{$ngram},$ref_ngrams_max{$ngram});
printf "%.2f info for each of $count %d-grams = '%s'\n", $ngram_info{$ngram}, scalar @wrds, $ngram
if $detail >= 3;
}
my $tst_length = @tst_wrds;
$min_tst_ref_length = $tst_length < $shortest_ref_length ? $tst_length : $shortest_ref_length;
print " min_ref:$shortest_ref_length, min_cand_ref: $min_tst_ref_length ";
return ($shortest_ref_length, $min_tst_ref_length, [@match_count], [@tst_count], [@ref_count], [@tst_info], [@ref_info]);
}
#################################
sub bleu_score {
my ($shortest_ref_length, $min_tst_ref_length, $matching_ngrams, $tst_ngrams, $sys, %SCOREmt) = @_;
print "short_ref_length: $shortest_ref_length min: $min_tst_ref_length \n";
my $score = 0;
my $iscore = 0;
#my $len_score = min (0, 1-$shortest_ref_length/$tst_ngrams->[1]);
my $len_score = 1-$shortest_ref_length/$min_tst_ref_length;
my $bp = exp($len_score);
print "bp: $len_score exp_bp: $bp\n";
for (my $j=1; $j<=$max_Ngram; $j++) {
if ($matching_ngrams->[$j] == 0) {
$SCOREmt{$j}{$sys}{cum}=0;
} else {
# Cumulative N-Gram score
$score += log ($matching_ngrams->[$j]/$tst_ngrams->[$j]);
$SCOREmt{$j}{$sys}{cum} = exp($score/$j + $len_score);
# Individual N-Gram score
$iscore = log ($matching_ngrams->[$j]/$tst_ngrams->[$j]);
$SCOREmt{$j}{$sys}{ind} = exp($iscore);
}
}
return $SCOREmt{4}{$sys}{cum};
}
#################################
sub nist_score {
my ($nsys, $matching_ngrams, $tst_ngrams, $ref_ngrams, $tst_info, $ref_info, $sys, %SCOREmt) = @_;
my $score = 0;
my $iscore = 0;
for (my $n=1; $n<=$max_Ngram; $n++) {
$score += $tst_info->[$n]/max($tst_ngrams->[$n],1);
$SCOREmt{$n}{$sys}{cum} = $score * nist_length_penalty($tst_ngrams->[1]/($ref_ngrams->[1]/$nsys));
$iscore = $tst_info->[$n]/max($tst_ngrams->[$n],1);
$SCOREmt{$n}{$sys}{ind} = $iscore * nist_length_penalty($tst_ngrams->[1]/($ref_ngrams->[1]/$nsys));
}
return $SCOREmt{5}{$sys}{cum};
}
#################################
sub Words2Ngrams { #convert a string of words to an Ngram count hash
my %count = ();
for (; @_; shift) {
my ($j, $ngram, $word);
for ($j=0; $j<$max_Ngram and defined($word=$_[$j]); $j++) {
$ngram .= defined $ngram ? " $word" : $word;
$count{$ngram}++;
}
}
return {%count};
}
#################################
sub NormalizeText {
my ($norm_text) = @_;
# language-independent part:
$norm_text =~ s/<skipped>//g; # strip "skipped" tags
$norm_text =~ s/-\n//g; # strip end-of-line hyphenation and join lines
$norm_text =~ s/\n/ /g; # join lines
$norm_text =~ s/"/"/g; # convert SGML tag for quote to "
$norm_text =~ s/&/&/g; # convert SGML tag for ampersand to &
$norm_text =~ s/</</g; # convert SGML tag for less-than to >
$norm_text =~ s/>/>/g; # convert SGML tag for greater-than to <
# language-dependent part (assuming Western languages):
$norm_text = " $norm_text ";
$norm_text =~ tr/[A-Z]/[a-z]/ unless $preserve_case;
$norm_text =~ s/([\{-\~\[-\` -\&\(-\+\:-\@\/])/ $1 /g; # tokenize punctuation
$norm_text =~ s/([^0-9])([\.,])/$1 $2 /g; # tokenize period and comma unless preceded by a digit
$norm_text =~ s/([\.,])([^0-9])/ $1 $2/g; # tokenize period and comma unless followed by a digit
$norm_text =~ s/([0-9])(-)/$1 $2 /g; # tokenize dash when preceded by a digit
$norm_text =~ s/\s+/ /g; # one space only between words
$norm_text =~ s/^\s+//; # no leading space
$norm_text =~ s/\s+$//; # no trailing space
return $norm_text;
}
#################################
sub nist_length_penalty {
my ($ratio) = @_;
return 1 if $ratio >= 1;
return 0 if $ratio <= 0;
my $ratio_x = 1.5;
my $score_x = 0.5;
my $beta = -log($score_x)/log($ratio_x)/log($ratio_x);
return exp (-$beta*log($ratio)*log($ratio));
}
#################################
sub date_time_stamp {
my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime();
my @months = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
my ($date, $time);
$time = sprintf "%2.2d:%2.2d:%2.2d", $hour, $min, $sec;
$date = sprintf "%4.4s %3.3s %s", 1900+$year, $months[$mon], $mday;
return ($date, $time);
}
#################################
sub extract_sgml_tag_and_span {
my ($name, $data) = @_;
($data =~ m|<$name\s*([^>]*)>(.*?)</$name\s*>(.*)|si) ? ($1, $2, $3) : ();
}
#################################
sub extract_sgml_tag_attribute {
my ($name, $data) = @_;
($data =~ m|$name\s*=\s*\"([^\"]*)\"|si) ? ($1) : ();
}
#################################
sub max {
my ($max, $next);
return unless defined ($max=pop);
while (defined ($next=pop)) {
$max = $next if $next > $max;
}
return $max;
}
#################################
sub min {
my ($min, $next);
return unless defined ($min=pop);
while (defined ($next=pop)) {
$min = $next if $next < $min;
}
return $min;
}
#################################
sub printout_report
{
if ( $METHOD eq "BOTH" ) {
foreach my $sys (sort @tst_sys) {
printf "NIST score = %2.4f BLEU score = %.4f for system \"$sys\"\n",$NISTmt{5}{$sys}{cum},$BLEUmt{4}{$sys}{cum};
}
} elsif ($METHOD eq "NIST" ) {
foreach my $sys (sort @tst_sys) {
printf "NIST score = %2.4f for system \"$sys\"\n",$NISTmt{5}{$sys}{cum};
}
} elsif ($METHOD eq "BLEU" ) {
foreach my $sys (sort @tst_sys) {
printf "\nBLEU score = %.4f for system \"$sys\"\n",$BLEUmt{4}{$sys}{cum};
}
}
printf "\n# ------------------------------------------------------------------------\n\n";
printf "Individual N-gram scoring\n";
printf " 1-gram 2-gram 3-gram 4-gram 5-gram 6-gram 7-gram 8-gram 9-gram\n";
printf " ------ ------ ------ ------ ------ ------ ------ ------ ------\n";
if (( $METHOD eq "BOTH" ) || ($METHOD eq "NIST")) {
foreach my $sys (sort @tst_sys) {
printf " NIST:";
for (my $i=1; $i<=$max_Ngram; $i++) {
printf " %2.4f ",$NISTmt{$i}{$sys}{ind}
}
printf " \"$sys\"\n";
}
printf "\n";
}
if (( $METHOD eq "BOTH" ) || ($METHOD eq "BLEU")) {
foreach my $sys (sort @tst_sys) {
printf " BLEU:";
for (my $i=1; $i<=$max_Ngram; $i++) {
printf " %2.4f ",$BLEUmt{$i}{$sys}{ind}
}
printf " \"$sys\"\n";
}
}
printf "\n# ------------------------------------------------------------------------\n";
printf "Cumulative N-gram scoring\n";
printf " 1-gram 2-gram 3-gram 4-gram 5-gram 6-gram 7-gram 8-gram 9-gram\n";
printf " ------ ------ ------ ------ ------ ------ ------ ------ ------\n";
if (( $METHOD eq "BOTH" ) || ($METHOD eq "NIST")) {
foreach my $sys (sort @tst_sys) {
printf " NIST:";
for (my $i=1; $i<=$max_Ngram; $i++) {
printf " %2.4f ",$NISTmt{$i}{$sys}{cum}
}
printf " \"$sys\"\n";
}
}
printf "\n";
if (( $METHOD eq "BOTH" ) || ($METHOD eq "BLEU")) {
foreach my $sys (sort @tst_sys) {
printf " BLEU:";
for (my $i=1; $i<=$max_Ngram; $i++) {
printf " %2.4f ",$BLEUmt{$i}{$sys}{cum}
}
printf " \"$sys\"\n";
}
}
}