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#include <iostream>
#include <cmath>
#include "lattice.h"
#include "stringlib.h"
#include "filelib.h"
#include "ttables.h"
#include "tdict.h"
using namespace std;
int main(int argc, char** argv) {
if (argc != 2) {
cerr << "Usage: " << argv[0] << " corpus.fr-en\n";
return 1;
}
const int ITERATIONS = 5;
const double BEAM_THRESHOLD = 0.0001;
TTable tt;
const WordID kNULL = TD::Convert("<eps>");
bool use_null = true;
TTable::Word2Word2Double was_viterbi;
for (int iter = 0; iter < ITERATIONS; ++iter) {
const bool final_iteration = (iter == (ITERATIONS - 1));
cerr << "ITERATION " << (iter + 1) << (final_iteration ? " (FINAL)" : "") << endl;
ReadFile rf(argv[1]);
istream& in = *rf.stream();
double likelihood = 0;
double denom = 0.0;
int lc = 0;
bool flag = false;
string line;
while(true) {
getline(in, line);
if (!in) break;
++lc;
if (lc % 1000 == 0) { cerr << '.'; flag = true; }
if (lc %50000 == 0) { cerr << " [" << lc << "]\n" << flush; flag = false; }
string ssrc, strg;
ParseTranslatorInput(line, &ssrc, &strg);
Lattice src, trg;
LatticeTools::ConvertTextToLattice(ssrc, &src);
LatticeTools::ConvertTextToLattice(strg, &trg);
if (src.size() == 0 || trg.size() == 0) {
cerr << "Error: " << lc << "\n" << line << endl;
assert(src.size() > 0);
assert(trg.size() > 0);
}
denom += trg.size();
vector<double> probs(src.size() + 1);
const double src_logprob = -log(src.size() + 1);
for (int j = 0; j < trg.size(); ++j) {
const WordID& f_j = trg[j][0].label;
double sum = 0;
if (use_null) {
probs[0] = tt.prob(kNULL, f_j);
sum += probs[0];
}
for (int i = 1; i <= src.size(); ++i) {
probs[i] = tt.prob(src[i-1][0].label, f_j);
sum += probs[i];
}
if (final_iteration) {
WordID max_i = 0;
double max_p = -1;
if (use_null) {
max_i = kNULL;
max_p = probs[0];
}
for (int i = 1; i <= src.size(); ++i) {
if (probs[i] > max_p) {
max_p = probs[i];
max_i = src[i-1][0].label;
}
}
was_viterbi[max_i][f_j] = 1.0;
} else {
if (use_null)
tt.Increment(kNULL, f_j, probs[0] / sum);
for (int i = 1; i <= src.size(); ++i)
tt.Increment(src[i-1][0].label, f_j, probs[i] / sum);
}
likelihood += log(sum) + src_logprob;
}
}
if (flag) { cerr << endl; }
cerr << " log likelihood: " << likelihood << endl;
cerr << " cross entropy: " << (-likelihood / denom) << endl;
cerr << " perplexity: " << pow(2.0, -likelihood / denom) << endl;
if (!final_iteration) tt.Normalize();
}
for (TTable::Word2Word2Double::iterator ei = tt.ttable.begin(); ei != tt.ttable.end(); ++ei) {
const TTable::Word2Double& cpd = ei->second;
const TTable::Word2Double& vit = was_viterbi[ei->first];
const string& esym = TD::Convert(ei->first);
double max_p = -1;
for (TTable::Word2Double::const_iterator fi = cpd.begin(); fi != cpd.end(); ++fi)
if (fi->second > max_p) max_p = fi->second;
const double threshold = max_p * BEAM_THRESHOLD;
for (TTable::Word2Double::const_iterator fi = cpd.begin(); fi != cpd.end(); ++fi) {
if (fi->second > threshold || (vit.count(fi->first) > 0)) {
cout << esym << ' ' << TD::Convert(fi->first) << ' ' << log(fi->second) << endl;
}
}
}
return 0;
}
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