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#!/usr/bin/env python3
# Copyright (c) 2010 Carnegie Mellon University
#
# You may copy and modify this freely under the same terms as
# Sphinx-III
"""
Find lattice word error rate using OpenFST.
"""
__author__ = "David Huggins-Daines <dhdaines@gmail.com>"
__version__ = "$Revision$"
import sys
import os
import re
import openfst
from cmusphinx import fstutils, lattice, lat2fsg
def is_filler(sym):
if sym == '<s>' or sym == '</s>':
return False
return ((sym[0] == '<' and sym[-1] == '>')
or (sym[0] == '+' and sym[-1] == '+'))
linere = re.compile(r"^\s*(?:<s>)?\s*([^(]+)(?:</s>)?\s*(?:\(([^)]+)\))\s*?")
def get_utt(line):
m = linere.match(line)
if m:
return m.groups()
else:
return (None, None)
class LevenshteinModel(openfst.StdVectorFst):
def __init__(self, symtab, scost=1, icost=1, dcost=1):
openfst.StdVectorFst.__init__(self)
st = self.AddState()
self.SetStart(st)
self.SetFinal(st, 0)
sigma = symtab.Find("σ")
for c, val in symtab:
if val in (openfst.epsilon, sigma):
continue
# Translation arc
self.AddArc(st, val, val, 0, st)
# Insertion/Deletion arcs
self.AddArc(st, 0, val, icost, st)
self.AddArc(st, val, 0, dcost, st)
# Substitution arcs
for cc, vv in symtab:
if vv in (openfst.epsilon, sigma, val):
continue
self.AddArc(st, val, vv, scost, st)
self.SetInputSymbols(symtab)
self.SetOutputSymbols(symtab)
class CompoundWordModel(openfst.StdVectorFst):
def __init__(self, isyms, osyms):
openfst.StdVectorFst.__init__(self)
st = self.AddState()
self.SetStart(st)
self.SetFinal(st, 0)
sigma = osyms.Find("σ")
for c, val in osyms:
if val in (openfst.epsilon, sigma):
continue
# Translation arc
self.AddArc(st, val, val, 0, st)
# Compound word separator
if '_' not in c:
continue
parts = c.split('_')
prev = st
nx = self.AddState()
# Transduce word sequence from input
isym = isyms.AddSymbol(parts[0])
self.AddArc(prev, isym, openfst.epsilon, 0, nx)
prev = nx
for p in parts[1:-1]:
nx = self.AddState()
isym = isyms.AddSymbol(p)
self.AddArc(prev, isym, openfst.epsilon, 0, nx)
prev = nx
isym = isyms.AddSymbol(parts[-1])
# Finally insert compound into output
self.AddArc(prev, isym, val, 0, st)
self.SetInputSymbols(isyms)
self.SetOutputSymbols(osyms)
if __name__ == '__main__':
from optparse import OptionParser
parser = OptionParser(usage="%prog CTL REF LATDIR")
parser.add_option("--prune", type="float")
opts, args = parser.parse_args(sys.argv[1:])
ctl, ref, latdir = args
ctl = open(ctl)
ref = open(ref)
wordcount = 0
errcount = 0
for c, r in zip(ctl, ref):
# Normalize reference, etc.
ref, refid = get_utt(r)
c = c.strip()
r = ref.split()
if len(r) == 0 or r[0] != '<s>':
r.insert(0, '<s>')
if r[-1] != '</s>':
r.append('</s>')
r = [x for x in r if not is_filler(x)]
# Turn it into an FSM
rfst = fstutils.sent2fst(r)
# Get the hypothesis lattice
try:
l = lattice.Dag(os.path.join(latdir, c + ".lat"))
except IOError:
try:
l = lattice.Dag(os.path.join(latdir, c + ".lat.gz"))
except IOError:
l = lattice.Dag(htk_file=os.path.join(latdir, c + ".slf"))
if opts.prune is not None:
l.posterior_prune(-opts.prune)
# Convert it to an FSM
lfst = lat2fsg.build_lattice_fsg(l,
rfst.OutputSymbols(),
addsyms=True,
determinize=False,
baseword=lattice.baseword_noclass)
openfst.ArcSortInput(lfst)
# Apply Levenshtein model to the input
errfst = LevenshteinModel(rfst.OutputSymbols())
openfst.ArcSortInput(errfst)
# Apply compound word model based on the lattice
compfst = CompoundWordModel(errfst.OutputSymbols(),
lfst.InputSymbols())
# Precompose and project it to the lattice so compound words
# are split in the alignment
xlat = openfst.StdVectorFst()
openfst.Compose(compfst, lfst, xlat)
openfst.ProjectInput(xlat)
openfst.ArcSortInput(xlat)
# Compose everything together
cfst = openfst.StdComposeFst(rfst, errfst)
cfst = openfst.StdComposeFst(cfst, xlat)
# Do bestpath search
ofst = openfst.StdVectorFst()
openfst.ShortestPath(cfst, ofst, 1)
st = ofst.Start()
err = 0
bt = []
while st != -1 and ofst.NumArcs(st):
a = ofst.GetArc(st, 0)
isym = ofst.InputSymbols().Find(a.ilabel)
osym = ofst.OutputSymbols().Find(a.olabel)
if isym == '</s>':
break
if a.ilabel == openfst.epsilon:
isym = '*INS*'
if a.olabel == openfst.epsilon:
osym = '*DEL*'
bt.append((isym, osym))
err += a.weight.Value()
st = a.nextstate
maxlen = [max([len(y) for y in x]) for x in bt]
nwords = len(r) - 2
refid = '(%s)' % refid
c = '(%s)' % c
print(" ".join(["%*s" % (m, x[0]) for m, x in zip(maxlen, bt)]), refid)
print(" ".join(["%*s" % (m, x[1]) for m, x in zip(maxlen, bt)]), c)
if nwords:
print("Error: %.2f%%" % (float(err) / nwords * 100))
else:
print("Error: %.2f%%" % (float(err) * 100))
print()
wordcount += nwords
errcount += err
print("TOTAL Error: %.2f%%" % (float(errcount) / wordcount * 100))
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