corpus.pm.svn-base

解码器是基于短语的统计机器翻译系统的核心模块

		push @$sentenceWER, $sentWER;
		push @$errIndices, $indices;
	}
	return ($totWER, $sentenceWER, $errIndices);
}

#arguments: system output (arrayref of arrayrefs of factor strings), truth (same), factor index to use
#return: wer score, arrayref of arrayrefs of indices of errorful words
sub sentenceWER
{
	#constants: direction we came through the table
	my ($DIR_NONE, $DIR_SKIPTRUTH, $DIR_SKIPOUT, $DIR_SKIPBOTH) = (-1, 0, 1, 2); #values don't matter but must be unique
	my ($self, $refSysOutput, $refTruth, $index) = @_;
	my ($totWER, $indices) = (0, []);
	my ($sLength, $eLength) = (scalar(@$refSysOutput), scalar(@$refTruth));
	if($sLength == 0 || $eLength == 0) {return ($totWER, $indices);} #special case
	
	my @refWordsMatchIndices = (-1) x $eLength; #at what sysout-word index this truth word is first matched
	my @sysoutWordsMatchIndices = (-1) x $sLength; #at what truth-word index this sysout word is first matched
	my $table = []; #index by sysout word index, then truth word index; a cell holds max count of matching words and direction we came to get it
	#dynamic-programming time: find the path through the table with the maximum number of matching words
	for(my $i = 0; $i < $sLength; $i++)
	{
		push @$table, [];
		for(my $j = 0; $j < $eLength; $j++)
		{
			my ($maxPrev, $prevDir) = (0, $DIR_NONE);
			if($i > 0 && $table->[$i - 1]->[$j]->[0] >= $maxPrev) {$maxPrev = $table->[$i - 1]->[$j]->[0]; $prevDir = $DIR_SKIPOUT;}
			if($j > 0 && $table->[$i]->[$j - 1]->[0] >= $maxPrev) {$maxPrev = $table->[$i]->[$j - 1]->[0]; $prevDir = $DIR_SKIPTRUTH;}
			if($i > 0 && $j > 0 && $table->[$i - 1]->[$j - 1]->[0] >= $maxPrev) {$maxPrev = $table->[$i - 1]->[$j - 1]->[0]; $prevDir = $DIR_SKIPBOTH;}
			my $match = ($refSysOutput->[$i]->[$index] eq $refTruth->[$j]->[$index] && $refWordsMatchIndices[$j] == -1 && $sysoutWordsMatchIndices[$i] == -1) ? 1 : 0;
			if($match == 1) {$refWordsMatchIndices[$j] = $i; $sysoutWordsMatchIndices[$i] = $j;}
			push @{$table->[$i]}, [($match ? $maxPrev + 1 : $maxPrev), $prevDir];
		}
	}
	
	#look back along the path and get indices of non-matching words
	my @unusedSysout = (0) x $sLength; #whether each sysout word was matched--used for outputting html table
	my ($i, $j) = ($sLength - 1, $eLength - 1);
	while($i > 0) #work our way back to the first sysout word
	{
		push @{$table->[$i]->[$j]}, 0; #length is flag to highlight cell
		if($table->[$i]->[$j]->[1] == $DIR_SKIPTRUTH)
		{
			$j--;
		}
		elsif($table->[$i]->[$j]->[1] == $DIR_SKIPOUT)
		{
			if($table->[$i - 1]->[$j]->[0] == $table->[$i]->[$j]->[0]) {unshift @$indices, $i; $unusedSysout[$i] = 1;}
			$i--;
		}
		elsif($table->[$i]->[$j]->[1] == $DIR_SKIPBOTH)
		{
			if($table->[$i - 1]->[$j - 1]->[0] == $table->[$i]->[$j]->[0]) {unshift @$indices, $i; $unusedSysout[$i] = 1;}
			$i--; $j--;
		}
	}
	#we're at the first sysout word; finish up checking for matches
	while($j > 0 && $refWordsMatchIndices[$j] != 0) {push @{$table->[0]->[$j]}, 0; $j--;}
	if($j == 0 && $refWordsMatchIndices[0] != 0) {unshift @$indices, 0; $unusedSysout[0] = 1;} #no truth word was matched to the first sysout word
	
	#print some HTML to debug the WER algorithm
#	print "<table border=1><tr><td></td><td>" . join("</td><td>", map {() . $_->[$index]} @$refTruth) . "</td></tr>";
#	for(my $i = 0; $i < $sLength; $i++)
#	{
#		print "<tr><td" . (($unusedSysout[$i] == 1) ? " style=\"background-color: #ffdd88\">" : ">") . $refSysOutput->[$i]->[$index] . "</td>";
#		for(my $j = 0; $j < $eLength; $j++)
#		{
#			print "<td";
#			if(scalar(@{$table->[$i]->[$j]}) > 2) {print " style=\"color: yellow; background-color: #000080\"";}
#			my $arrow;
#			if($table->[$i]->[$j]->[1] == $DIR_NONE) {$arrow = "&times;";}
#			elsif($table->[$i]->[$j]->[1] == $DIR_SKIPTRUTH) {$arrow = "&larr;";}
#			elsif($table->[$i]->[$j]->[1] == $DIR_SKIPOUT) {$arrow = "&uarr;";}
#			elsif($table->[$i]->[$j]->[1] == $DIR_SKIPBOTH) {$arrow = "&loz;";}
#			print ">" . $table->[$i]->[$j]->[0] . "  " . $arrow . "</td>";
#		}
#		print "</tr>";
#	}
#	print "</table>";
	
	my $matchCount = 0;
	if($sLength > 0) {$matchCount = $table->[$sLength - 1]->[$eLength - 1]->[0];}
	return ($sLength - $matchCount, $indices);
}

#arguments: system output (arrayref of arrayrefs of arrayrefs of factor strings), truth (same), factor index to use
#return: wer score, arrayref of sentence scores, arrayref of arrayrefs of indices of errorful words
sub corpusPWER
{
	my ($self, $refSysOutput, $refTruth, $index) = @_;
	my ($totWER, $sentenceWER, $errIndices) = (0, [], []);
	for(my $i = 0; $i < scalar(@$refSysOutput); $i++)
	{
		my ($sentWER, $indices) = $self->sentencePWER($refSysOutput->[$i], $refTruth->[$i], $index);
		$totWER += $sentWER;
		push @$sentenceWER, $sentWER;
		push @$errIndices, $indices;
	}
	return ($totWER, $sentenceWER, $errIndices);
}

#arguments: system output (arrayref of arrayrefs of factor strings), truth (same), factor index to use
#return: wer score, arrayref of arrayrefs of indices of errorful words
sub sentencePWER
{
	my ($self, $refSysOutput, $refTruth, $index) = @_;
	my ($totWER, $indices) = (0, []);
	my ($sLength, $eLength) = (scalar(@$refSysOutput), scalar(@$refTruth));
	my @truthWordUsed = (0) x $eLength; #array of 0/1; can only match a given truth word once
	for(my $j = 0; $j < $sLength; $j++)
	{
		my $found = 0;
		for(my $k = 0; $k < $eLength; $k++) #check output word against entire truth sentence
		{
			if(lc $refSysOutput->[$j]->[$index] eq lc $refTruth->[$k]->[$index] && $truthWordUsed[$k] == 0)
			{
				$truthWordUsed[$k] = 1;
				$found = 1;
				last;
			}
		}
		if($found == 0)
		{
			$totWER++;
			push @$indices, $j;
		}
	}
	return ($totWER, $indices);
}

#BLEU calculation for a single sentence
#arguments: truth sentence (arrayref of arrayrefs of factor strings), sysout sentence (same), factor index to use
#return: 1- through 4-gram matching and total counts (1-g match, 1-g tot, 2-g match...), candidate length, reference length
sub sentenceBLEU
{
	my ($self, $refTruth, $refSysOutput, $factorIndex, $debug) = @_;
	my ($length_reference, $length_translation) = (scalar(@$refTruth), scalar(@$refSysOutput));
	my ($correct1, $correct2, $correct3, $correct4, $total1, $total2, $total3, $total4) = (0, 0, 0, 0, 0, 0, 0, 0);
	my %REF_GRAM = ();
	my ($i, $gram);
	for($i = 0; $i < $length_reference; $i++)
	{
		$gram = $refTruth->[$i]->[$factorIndex];
		$REF_GRAM{$gram}++;
		next if $i<1;
		$gram = $refTruth->[$i - 1]->[$factorIndex] ." ".$gram;
		$REF_GRAM{$gram}++;
      next if $i<2;
      $gram = $refTruth->[$i - 2]->[$factorIndex] ." ".$gram;
      $REF_GRAM{$gram}++;
      next if $i<3;
      $gram = $refTruth->[$i - 3]->[$factorIndex] ." ".$gram;
      $REF_GRAM{$gram}++;
	}
	for($i = 0; $i < $length_translation; $i++)
	{
      $gram = $refSysOutput->[$i]->[$factorIndex];
      if (defined($REF_GRAM{$gram}) && $REF_GRAM{$gram} > 0) {
			$REF_GRAM{$gram}--;
			$correct1++;
      }
      next if $i<1;
      $gram = $refSysOutput->[$i - 1]->[$factorIndex] ." ".$gram;
      if (defined($REF_GRAM{$gram}) && $REF_GRAM{$gram} > 0) {
			$REF_GRAM{$gram}--;
			$correct2++;
      }
      next if $i<2;
      $gram = $refSysOutput->[$i - 2]->[$factorIndex] ." ".$gram;
      if (defined($REF_GRAM{$gram}) && $REF_GRAM{$gram} > 0) {
			$REF_GRAM{$gram}--;
			$correct3++;
      }
      next if $i<3;
      $gram = $refSysOutput->[$i - 3]->[$factorIndex] ." ".$gram;
      if (defined($REF_GRAM{$gram}) && $REF_GRAM{$gram} > 0) {
			$REF_GRAM{$gram}--;
			$correct4++;
      }
	}
	my $total = $length_translation;
	$total1 = max(1, $total);
	$total2 = max(1, $total - 1);
	$total3 = max(1, $total - 2);
	$total4 = max(1, $total - 3);
	
	return ($correct1, $total1, $correct2, $total2, $correct3, $total3, $correct4, $total4, $length_translation, $length_reference);
}

##### filesystem #####

#open as many given files as possible; only warn about the rest
#arguments: list of filename extensions to open (assume corpus name is file title)
#return: hash from type string to filehandleref, giving all files that were successfully opened
sub openFiles
{
	my ($self, @extensions) = @_;
	my %openedFiles = ();
	foreach my $ext (@extensions)
	{
		if(!open(FILE, "<" . $self->{'corpusName'} . $ext))
		{
			warn "Corpus::openFiles(): couldn't open '" . $self->{'corpusName'} . $ext . "' for read\n";
		}
		else #success
		{
			$openedFiles{$ext} = \*FILE;
		}
	}
	return %openedFiles;
}

#read one line from each given file
#arguments: hash from type string to filehandleref
#return: hash from type string to sentence (stored as arrayref of arrayrefs of factors) read from corresponding file
sub readLineFromFiles
{
	my ($self, %openedFiles) = @_;
	my %lines;
	foreach my $type (keys %openedFiles)
	{
		$lines{$type} = [];
		my $sentence = <$openedFiles{$type}>;
		my @words = split(/\s+/, $sentence);
		foreach my $word (@words)
		{
			my @factors = split(/\|/, $word);
			push @{$lines{$type}}, \@factors;
		}
	}
	return %lines;
}

#close all given files
#arguments: hash from type string to filehandleref
#return: none
sub closeFiles
{
	my ($self, %openedFiles) = @_;
	foreach my $type (keys %openedFiles)
	{
		close($openedFiles{$type});
	}
}

##### write HTML #####

#print HTML for comparing various versions of a sentence, with special processing for each version as appropriate
#arguments: filehandleref to which to write, sentence ID string, hashref of version string to sentence (stored as arrayref of arrayref of factor strings)
#return: none
sub printSingleSentenceComparison
{
	my ($self, $fh, $sentID, $sentences) = @_;
	my $curFH = select;
	select $fh;
	#javascript to reorder rows to look nice afterward
	print "<script type=\"text/javascript\">
	function reorder_$sentID()
	{/*
		var table = document.getElementById('div_$sentID').firstChild;
		var refTransRow = table.getElementById('row_e');
		var inputRow = table.getElementById('row_f');
		table.removeRow(refTransRow);
		table.removeRow(inputRow);
		var newRow1 = table.insertRow(0);
		var newRow2 = table.insertRow(1);
		newRow1.childNodes = inputRow.childNodes;
		newRow2.childNodes = refTransRow.childNodes;*/
	}
	</script>";
	#html for sentences
	print "<div id=\"div_$sentID\" style=\"padding: 3px; margin: 5px\">";
	print "<table border=\"1\">";
#	my $rowCount = 0;
#	my @bgColors = ("#ffefbf", "#ffdf7f");
	#process all rows in order
	foreach my $sentType (keys %$sentences)
	{
		my $bgcolor = $bgColors[$rowCount % 2];
		print "<tr id=\"row_$sentType\"><td align=right>";
		#description of sentence
		if(defined($self->{'fileDescriptions'}->{$self->{'corpusName'} . $sentType}))
		{
			print "(" . $self->{'fileDescriptions'}->{$self->{'corpusName'} . $sentType} . ")";
		}
		else
		{
			print "($sentType)";
		}
		print "</td><td align=left>";
		#sentence with markup
		if($sentType eq 'f') #input
		{
#			$self->writeHTMLSentenceWithFactors($fh, $sentences->{$sentType}, $inputColor);
		}
		elsif($sentType eq 'e') #reference translation
		{
#			$self->writeHTMLSentenceWithFactors($fh, $sentences->{$sentType}, $reftransColor);
		}
		else #system output
		{
#			$self->writeHTMLTranslationHighlightedWithFactors($fh, $sentences->{$sentType}, $sentences->{'e'}, $highlightColors);
		}
		print "</td></tr>";
#		$rowCount++;
	}
	print "</table>";
	print "</div>\n";
	select $curFH;
}

#print contents of all fields of this object, with useful formatting for arrayrefs and hashrefs
#arguments: none
#return: none
sub printDetails
{
	my $self = shift;
	foreach my $key (keys %$self)
	{
		if(ref($self->{$key}) eq 'HASH')
		{
			print STDERR "obj: $key => {" . join(', ', map {"$_ => " . $self->{$key}->{$_}} (keys %{$self->{$key}})) . "}\n";
		}
		elsif(ref($self->{$key}) eq 'ARRAY')
		{
			print STDERR "obj: $key => (" . join(', ', @{$self->{$key}}) . ")\n";
		}
		elsif(ref($self->{$key}) eq '') #not a reference
		{
			print STDERR "obj: $key => " . $self->{$key} . "\n";
		}
	}
}