format_lm_sri.sh
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#!/bin/bash
# Copyright 2012 Arnab Ghoshal
# Copyright 2010-2011 Microsoft Corporation
# 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
#
# THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
# WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
# MERCHANTABLITY OR NON-INFRINGEMENT.
# See the Apache 2 License for the specific language governing permissions and
# limitations under the License.
# Begin configuration section.
srilm_opts="-subset -prune-lowprobs -unk -tolower"
# end configuration sections
help_message="Usage: "`basename $0`" [options] lang_dir LM lexicon out_dir
Convert ARPA-format language models to FSTs. Change the LM vocabulary using SRILM.\n
options:
--help # print this message and exit
--srilm-opts STRING # options to pass to SRILM tools (default: '$srilm_opts')
";
. utils/parse_options.sh
if [ $# -ne 4 ]; then
printf "$help_message\n";
exit 1;
fi
lang_dir=$1
lm=$2
lexicon=$3
out_dir=$4
mkdir -p $out_dir
[ -f ./path.sh ] && . ./path.sh
loc=`which change-lm-vocab`
if [ -z $loc ]; then
if uname -a | grep 64 >/dev/null; then # some kind of 64 bit...
sdir=`pwd`/../../../tools/srilm/bin/i686-m64
else
sdir=`pwd`/../../../tools/srilm/bin/i686
fi
if [ -f $sdir/../change-lm-vocab ]; then
echo Using SRILM tools from $sdir
export PATH=$PATH:$sdir:$sdir/..
else
echo You appear to not have SRILM tools installed, either on your path,
echo or installed in $sdir. See tools/install_srilm.sh for installation
echo instructions.
exit 1
fi
fi
echo "Converting '$lm' to FST"
tmpdir=$(mktemp -d);
trap 'rm -rf "$tmpdir"' EXIT
for f in phones.txt words.txt L.fst L_disambig.fst phones/; do
cp -r $lang_dir/$f $out_dir || exit 1;
done
lm_base=$(basename $lm '.gz')
gunzip -c $lm | utils/find_arpa_oovs.pl $out_dir/words.txt \
> $out_dir/oovs_${lm_base}.txt || exit 1;
# Removing all "illegal" combinations of <s> and </s>, which are supposed to
# occur only at being/end of utt. These can cause determinization failures
# of CLG [ends up being epsilon cycles].
gunzip -c $lm \
| egrep -v '<s> <s>|</s> <s>|</s> </s>' \
| gzip -c > $tmpdir/lm.gz || exit 1;
awk '{print $1}' $out_dir/words.txt > $tmpdir/voc || exit 1;
# Change the LM vocabulary to be the intersection of the current LM vocabulary
# and the set of words in the pronunciation lexicon. This also renormalizes the
# LM by recomputing the backoff weights, and remove those ngrams whose
# probabilities are lower than the backed-off estimates.
change-lm-vocab -vocab $tmpdir/voc -lm $tmpdir/lm.gz -write-lm $tmpdir/out_lm \
$srilm_opts || exit 1;
arpa2fst $tmpdir/out_lm | fstprint \
| utils/eps2disambig.pl | utils/s2eps.pl \
| fstcompile --isymbols=$out_dir/words.txt --osymbols=$out_dir/words.txt \
--keep_isymbols=false --keep_osymbols=false \
| fstrmepsilon > $out_dir/G.fst || exit 1;
fstisstochastic $out_dir/G.fst
# The output is like:
# 9.14233e-05 -0.259833
# we do expect the first of these 2 numbers to be close to zero (the second is
# nonzero because the backoff weights make the states sum to >1).
# Everything below is only for diagnostic.
# Checking that G has no cycles with empty words on them (e.g. <s>, </s>);
# this might cause determinization failure of CLG.
# #0 is treated as an empty word.
mkdir -p $out_dir/tmpdir.g
awk '{if(NF==1){ printf("0 0 %s %s\n", $1,$1); }}
END{print "0 0 #0 #0"; print "0";}' \
< "$lexicon" > $out_dir/tmpdir.g/select_empty.fst.txt || exit 1;
fstcompile --isymbols=$out_dir/words.txt --osymbols=$out_dir/words.txt \
$out_dir/tmpdir.g/select_empty.fst.txt \
| fstarcsort --sort_type=olabel \
| fstcompose - $out_dir/G.fst > $out_dir/tmpdir.g/empty_words.fst || exit 1;
fstinfo $out_dir/tmpdir.g/empty_words.fst | grep cyclic | grep -w 'y' \
&& echo "Language model has cycles with empty words" && exit 1
rm -r $out_dir/tmpdir.g
echo "Succeeded in formatting LM: '$lm'"