File size: 8,667 Bytes
b0dd4bf |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 |
#!/usr/bin/env perl
# Processes enhanced graphs in a CoNLL-U file so that empty nodes are removed
# and paths that traverse them are collapsed into individual edges whose labels
# show the original path, either with or without the ids of the empty nodes:
# "conj>33.1>nsubj" or "conj>nsubj".
# Copyright © 2020 Dan Zeman <zeman@ufal.mff.cuni.cz>
# License: GNU GPL
use utf8;
use open ':utf8';
binmode(STDIN, ':utf8');
binmode(STDOUT, ':utf8');
binmode(STDERR, ':utf8');
use List::MoreUtils qw(any);
# We need to tell Perl where to find my graph modules.
# If this does not work, you can put the script together with Graph.pm and
# Node.pm in a folder of you choice, say, /home/joe/scripts, and then
# invoke Perl explicitly telling it where the modules are:
# perl -I/home/joe/scripts /home/joe/scripts/enhanced_collapse_empty_nodes.pl inputfile.conllu
BEGIN
{
use Cwd;
my $path = $0;
my $currentpath = getcwd();
$currentpath =~ s/\r?\n$//;
$libpath = $currentpath;
if($path =~ m:/:)
{
$path =~ s:/[^/]*$:/:;
chdir($path);
$libpath = getcwd();
chdir($currentpath);
}
$libpath =~ s/\r?\n$//;
#print STDERR ("libpath=$libpath\n");
}
use lib $libpath;
use Graph;
use Node;
my @sentence;
while(<>)
{
if(m/^\s*$/)
{
process_sentence(@sentence);
@sentence = ();
}
else
{
s/\r?\n$//;
push(@sentence, $_);
}
}
# In case of incorrect files that lack the last empty line:
if(scalar(@sentence) > 0)
{
process_sentence(@sentence);
}
#------------------------------------------------------------------------------
# Processes one sentence after it has been read.
#------------------------------------------------------------------------------
sub process_sentence
{
my @sentence = @_;
my $graph = Graph::from_conllu_lines(@sentence);
# We now have a complete representation of the graph.
collapse_empty_nodes($graph);
# Now get the list of CoNLL-U lines from the modified graph.
@sentence = $graph->to_conllu_lines();
print_sentence(@sentence);
# Make sure that the graph gets properly destroyed. Remove cyclic references.
$graph->remove_all_nodes();
}
#------------------------------------------------------------------------------
# Prints a sentence in the CoNLL-U format to the standard output.
#------------------------------------------------------------------------------
sub print_sentence
{
my @sentence = @_;
print(join("\n", @sentence), "\n\n");
}
#------------------------------------------------------------------------------
# Processes the enhanced graph and collapses paths traversing empty nodes.
#------------------------------------------------------------------------------
sub collapse_empty_nodes
{
my $graph = shift; # a Graph object
my @nodes = $graph->get_nodes();
my @edges;
foreach my $node (@nodes)
{
my $cid = $node->id();
my @iedges = @{$node->iedges()};
foreach my $iedge (@iedges)
{
my $pid = $iedge->{id};
my $deprel = $iedge->{deprel};
push(@edges, [$pid, $deprel, $cid]);
}
}
my @okedges = grep {$_->[0] =~ m/^\d+$/ && $_->[-1] =~ m/^\d+$/} (@edges);
my @epedges = grep {$_->[0] =~ m/^\d+\.\d+$/} (@edges); # including those that have also empty child
my @ecedges = grep {$_->[-1] =~ m/^\d+\.\d+$/} (@edges); # including those that have also empty parent
my %epedges; # hash of serialized edges: make sure not to add an edge that is already there
foreach my $epedge (@epedges)
{
$epedges{join(' ', @{$epedge})}++;
}
my %ecedges;
foreach my $ecedge (@ecedges)
{
$ecedges{join(' ', @{$ecedge})}++;
}
while(@epedges)
{
my $epedge = shift(@epedges);
my @myecedges = grep {$_->[-1] eq $epedge->[0]} (@ecedges);
if(scalar(@myecedges)==0)
{
print STDERR ('Ignoring enhanced path because the empty source node does not have any parent: '.join('>', @epedge)."\n");
}
foreach my $ecedge (@myecedges)
{
my @newedge = @{$ecedge};
pop(@newedge);
push(@newedge, @{$epedge});
# Cyclic paths need special treatment. We do not want to fall in an endless loop.
# However, if both ends of the path are non-empty nodes (even if it is the same non-empty node),
# we can add the edge to @okedges. Note that self-loop edges are normally not allowed in
# enhanced graphs; however, in this collapsed form they can still preserve information
# that would disappear otherwise.
if($newedge[0] =~ m/^\d+$/ && $newedge[-1] =~ m/^\d+$/)
{
push(@okedges, \@newedge);
}
else
{
# This edge is not OK because it still begins or ends in an empty node.
# We will use it for creation of longer edges but only if it does not contain a cycle.
my $cycle = 0;
my %map;
for(my $i = 0; $i <= $#newedge; $i += 2)
{
if(exists($map{$newedge[$i]}))
{
$cycle = 1;
last;
}
$map{$newedge[$i]}++;
}
unless($cycle)
{
if($newedge[0] =~ m/^\d+\.\d+$/)
{
my $serialized = join(' ', @newedge);
unless(exists($epedges{$serialized}))
{
push(@epedges, \@newedge);
$epedges{$serialized}++;
}
}
if($newedge[-1] =~ m/^\d+\.\d+$/)
{
my $serialized = join(' ', @newedge);
unless(exists($ecedges{$serialized}))
{
push(@ecedges, \@newedge);
}
}
}
else
{
print STDERR ('Cyclic enhanced path will not be used to construct longer paths: '.join('>', @newedge)."\n");
}
}
}
}
# Now there are no more @epedges (while @ecedges grew over time but we do not care now).
# All edges in @okedges have non-empty ends.
@okedges = sort {my $r = $a->[-1] <=> $b->[-1]; unless($r) {$r = $a->[0] <=> $b->[0]} $r} (@okedges);
# Empty nodes normally should not be leaves but it is not guaranteed.
# Issue a warning if an empty node disappears because it has no children.
my %oknodes;
foreach my $okedge (@okedges)
{
foreach my $item (@{$okedge})
{
if($item =~ m/^\d+\.\d+$/)
{
$oknodes{$item}++;
}
}
}
foreach my $ecedge (@ecedges)
{
my $item = $ecedge->[-1];
if(!exists($oknodes{$item}))
{
print STDERR ('Incoming path to an empty node ignored because the node has no children: '.join('>', @{$ecedge})."\n");
}
}
# Remove all edges going to or from an empty node, then remove the empty nodes as well.
foreach my $node (@nodes)
{
if($node->id() =~ m/\./)
{
my @iedges = @{$node->iedges()};
foreach my $iedge (@iedges)
{
$graph->remove_edge($iedge->{id}, $node->id(), $iedge->{deprel});
}
my @oedges = @{$node->oedges()};
foreach my $oedge (@oedges)
{
$graph->remove_edge($node->id(), $oedge->{id}, $oedge->{deprel});
}
$graph->remove_node($node->id());
}
}
# Add the new collapsed edges to the graph.
foreach my $edge (@okedges)
{
my @edge = @{$edge};
my $pid = shift(@edge);
my $cid = pop(@edge);
# Skip simple edges because they are already in the graph.
next unless(scalar(@edge) > 1);
my $deprel = join('>', @edge);
# Remove the ids of the empty nodes from the path.
###!!! We may want to parameterize this step because we may want to preserve
###!!! the ids in some use cases. However, for the sake of the evaluation of
###!!! the EUD shared task, we want to get rid of them.
$deprel =~ s/>\d+\.\d+>/>/g;
# Add the collapsed edge to the graph.
$graph->add_edge($pid, $cid, $deprel);
}
}
|