reranker

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@725 ec762483-ff6d-05da-a07a-a48fb63a330f

1 files changed, 77 insertions, 0 deletions

diff --git a/rescore/rerank.pl b/rescore/rerank.pl
new file mode 100755
index 00000000..ce7a67bd
--- /dev/null
+++ b/rescore/rerank.pl
@@ -0,0 +1,77 @@
+#!/usr/bin/perl -w
+
+use strict;
+use utf8;
+use Getopt::Long;
+
+my $weights_file;
+my $hyp_file;
+my $help;
+
+Getopt::Long::Configure("no_auto_abbrev");
+if (GetOptions(
+    "weights_file|w=s" => \$weights_file,
+    "hypothesis_file|h=s" => \$hyp_file,
+    "help" => \$help,
+) == 0 || @ARGV!=0 || $help || !$weights_file || !$hyp_file) {
+  usage();
+  exit(1);
+}
+
+open W, "<$weights_file" or die "Can't read $weights_file: $!";
+my %weights;
+while(<W>) {
+  chomp;
+  next if /^#/;
+  next if /^\s*$/;
+  my ($fname, $w) = split /\s+/;
+  $weights{$fname} = $w;
+}
+close W;
+
+my $cur = undef;
+my %hyps = ();
+open HYP, "<$hyp_file" or die "Can't read $hyp_file: $!";
+while(<HYP>) {
+  chomp;
+  my ($id, $hyp, $feats) = split / \|\|\| /;
+  unless (defined $cur) { $cur = $id; }
+  if ($cur ne $id) {
+    extract_1best(\%hyps);
+    $cur = $id;
+    %hyps = ();
+  }
+  my @afeats = split /\s+/, $feats;
+  my $tot = 0;
+  for my $featpair (@afeats) {
+    my ($fname,$fval) = split /=/, $featpair;
+    my $weight = $weights{$fname};
+    die "Unweighted feature '$fname'" unless defined $weight;
+    $tot += ($weight * $fval);
+  }
+  $hyps{$hyp} = $tot;
+}
+extract_1best(\%hyps) if defined $cur;
+close HYP;
+
+sub extract_1best {
+  my $rh = shift;
+  my %hyps = %$rh;
+  my $best_score = undef;
+  my $best_hyp = undef;
+  for my $hyp (keys %hyps) {
+    if (!defined $best_score || $hyps{$hyp} > $best_score) {
+      $best_score = $hyps{$hyp};
+      $best_hyp = $hyp;
+    }
+  }
+  print "$best_hyp\n";
+}
+
+sub usage {
+  print <<EOT;
+Usage: $0 -w weights.txt -h hyp.nbest.txt
+  Reranks n-best lists with new weights, extracting the new 1-best entries.
+EOT
+}
+