add initial files for deployment

deploy/ctc_beam_search_decoder.cpp

+#include <iostream>
+#include <map>
+#include <algorithm>
+#include <utility>
+#include <cmath>
+#include "ctc_beam_search_decoder.h"
+
+template <typename T1, typename T2>
+bool pair_comp_first_rev(const std::pair<T1, T2> a, const std::pair<T1, T2> b) {
+    return a.first > b.first;
+}
+
+template <typename T1, typename T2>
+bool pair_comp_second_rev(const std::pair<T1, T2> a, const std::pair<T1, T2> b) {
+    return a.second > b.second;
+}
+
+/* CTC beam search decoder in C++, the interface is consistent with the original 
+   decoder in Python version.
+*/
+std::vector<std::pair<double, std::string> > 
+           ctc_beam_search_decoder(std::vector<std::vector<double> > probs_seq,
+                                   int beam_size,
+                                   std::vector<std::string> vocabulary,
+                                   int blank_id,
+                                   double cutoff_prob,
+                                   Scorer *ext_scorer,
+                                   bool nproc
+                                  )
+{
+    int num_time_steps = probs_seq.size();
+    
+    // assign space ID 
+    std::vector<std::string>::iterator it = std::find(vocabulary.begin(), vocabulary.end(), " ");
+    int space_id = it-vocabulary.begin();
+    if(space_id >= vocabulary.size()) {
+        std::cout<<"The character space is not in the vocabulary!";
+        exit(1); 
+    }
+    
+    // initialize
+    // two sets containing selected and candidate prefixes respectively
+    std::map<std::string, double> prefix_set_prev, prefix_set_next;
+    // probability of prefixes ending with blank and non-blank
+    std::map<std::string, double> probs_b_prev, probs_nb_prev;
+    std::map<std::string, double> probs_b_cur, probs_nb_cur;
+    prefix_set_prev["\t"] = 1.0;
+    probs_b_prev["\t"] = 1.0;
+    probs_nb_prev["\t"] = 0.0;
+    
+    for (int time_step=0; time_step<num_time_steps; time_step++) {
+        prefix_set_next.clear();
+        probs_b_cur.clear();
+        probs_nb_cur.clear();
+        std::vector<double> prob = probs_seq[time_step];
+
+        std::vector<std::pair<int, double> > prob_idx;
+        for (int i=0; i<prob.size(); i++) {
+            prob_idx.push_back(std::pair<int, double>(i, prob[i]));
+        }
+        // pruning of vacobulary
+        if (cutoff_prob < 1.0) {
+            std::sort(prob_idx.begin(), prob_idx.end(), pair_comp_second_rev<int, double>);
+            float cum_prob = 0.0;
+            int cutoff_len = 0;
+            for (int i=0; i<prob_idx.size(); i++) {
+                cum_prob += prob_idx[i].second;
+                cutoff_len += 1;
+                if (cum_prob >= cutoff_prob) break;
+            }
+            prob_idx = std::vector<std::pair<int, double> >(prob_idx.begin(), prob_idx.begin()+cutoff_len);
+        }
+        // extend prefix 
+        for (std::map<std::string, double>::iterator it = prefix_set_prev.begin(); 
+            it != prefix_set_prev.end(); it++) {
+            std::string l = it->first;
+            if( prefix_set_next.find(l) == prefix_set_next.end()) {
+                probs_b_cur[l] = probs_nb_cur[l] = 0.0;
+            }
+
+            for (int index=0; index<prob_idx.size(); index++) {
+                int c = prob_idx[index].first;
+                double prob_c = prob_idx[index].second;
+                if (c == blank_id) {
+                    probs_b_cur[l] += prob_c*(probs_b_prev[l]+probs_nb_prev[l]);
+                } else {
+                    std::string last_char = l.substr(l.size()-1, 1);
+                    std::string new_char = vocabulary[c];
+                    std::string l_plus = l+new_char;
+
+                    if( prefix_set_next.find(l_plus) == prefix_set_next.end()) {
+                        probs_b_cur[l_plus] = probs_nb_cur[l_plus] = 0.0;
+                    }
+                    if (last_char == new_char) {
+                        probs_nb_cur[l_plus] += prob_c * probs_b_prev[l];
+                        probs_nb_cur[l] += prob_c * probs_nb_prev[l];
+                    } else if (new_char == " ") {
+                        double score = 1.0;
+                        if (ext_scorer != NULL && l.size() > 1) {
+                            score = ext_scorer->get_score(l.substr(1));
+                        }
+                        probs_nb_cur[l_plus] += score * prob_c * (
+                            probs_b_prev[l] + probs_nb_prev[l]);
+                    } else {
+                        probs_nb_cur[l_plus] += prob_c * (
+                            probs_b_prev[l] + probs_nb_prev[l]);
+                    }
+                    prefix_set_next[l_plus] = probs_nb_cur[l_plus]+probs_b_cur[l_plus];
+                }
+            }
+
+            prefix_set_next[l] = probs_b_cur[l]+probs_nb_cur[l];  
+        }
+
+        probs_b_prev = probs_b_cur;
+        probs_nb_prev = probs_nb_cur;
+        std::vector<std::pair<std::string, double> > 
+                  prefix_vec_next(prefix_set_next.begin(), prefix_set_next.end());
+        std::sort(prefix_vec_next.begin(), prefix_vec_next.end(), pair_comp_second_rev<std::string, double>);
+        int k = beam_size<prefix_vec_next.size() ? beam_size : prefix_vec_next.size();
+        prefix_set_prev = std::map<std::string, double>
+                  (prefix_vec_next.begin(), prefix_vec_next.begin()+k);
+    }
+
+    // post processing
+    std::vector<std::pair<double, std::string> > beam_result;
+    for (std::map<std::string, double>::iterator it = prefix_set_prev.begin(); 
+         it != prefix_set_prev.end(); it++) {
+        if (it->second > 0.0 && it->first.size() > 1) {
+            double prob = it->second;
+            std::string sentence = it->first.substr(1);
+            // scoring the last word
+            if (ext_scorer != NULL && sentence[sentence.size()-1] != ' ') {
+                prob = prob * ext_scorer->get_score(sentence);
+            }
+            double log_prob = log(it->second);
+            beam_result.push_back(std::pair<double, std::string>(log_prob, it->first));
+        }
+    }
+    // sort the result and return
+    std::sort(beam_result.begin(), beam_result.end(), pair_comp_first_rev<double, std::string>);
+    return beam_result;
+}

deploy/ctc_beam_search_decoder.h

+#ifndef CTC_BEAM_SEARCH_DECODER_H_
+#define CTC_BEAM_SEARCH_DECODER_H_
+
+#include <vector>
+#include <string>
+#include <utility>
+#include "scorer.h"
+
+std::vector<std::pair<double, std::string> > 
+           ctc_beam_search_decoder(std::vector<std::vector<double> > probs_seq,
+                                   int beam_size,
+                                   std::vector<std::string> vocabulary,
+                                   int blank_id=0,
+                                   double cutoff_prob=1.0,
+                                   Scorer *ext_scorer=NULL,
+                                   bool nproc=false
+                                  );
+
+#endif // CTC_BEAM_SEARCH_DECODER_H_

deploy/ctc_beam_search_decoder.i

+%module swig_ctc_beam_search_decoder
+%{
+#include "ctc_beam_search_decoder.h"
+%}
+
+%include "std_vector.i"
+%include "std_pair.i"
+%include "std_string.i"
+
+namespace std{
+    %template(DoubleVector) std::vector<double>;
+    %template(IntVector) std::vector<int>;
+    %template(StringVector) std::vector<std::string>;
+    %template(VectorOfStructVector) std::vector<std::vector<double> >;
+    %template(FloatVector) std::vector<float>;
+    %template(Pair) std::pair<float, std::string>;
+    %template(PairFloatStringVector)  std::vector<std::pair<float, std::string> >;
+    %template(PairDoubleStringVector) std::vector<std::pair<double, std::string> >;
+}
+
+%import scorer.h
+%include "ctc_beam_search_decoder.h"

deploy/decoder_setup.py

+from setuptools import setup, Extension
+import glob
+import platform
+import os
+
+
+def compile_test(header, library):
+    dummy_path = os.path.join(os.path.dirname(__file__), "dummy")
+    command = "bash -c \"g++ -include " + header + " -l" + library + " -x c++ - <<<'int main() {}' -o " + dummy_path + " >/dev/null 2>/dev/null && rm " + dummy_path + " 2>/dev/null\""
+    return os.system(command) == 0
+
+
+FILES = glob.glob('util/*.cc') + glob.glob('lm/*.cc') + glob.glob(
+    'util/double-conversion/*.cc')
+FILES = [
+    fn for fn in FILES if not (fn.endswith('main.cc') or fn.endswith('test.cc'))
+]
+
+LIBS = ['stdc++']
+if platform.system() != 'Darwin':
+    LIBS.append('rt')
+
+ARGS = ['-O3', '-DNDEBUG', '-DKENLM_MAX_ORDER=6']
+
+if compile_test('zlib.h', 'z'):
+    ARGS.append('-DHAVE_ZLIB')
+    LIBS.append('z')
+
+if compile_test('bzlib.h', 'bz2'):
+    ARGS.append('-DHAVE_BZLIB')
+    LIBS.append('bz2')
+
+if compile_test('lzma.h', 'lzma'):
+    ARGS.append('-DHAVE_XZLIB')
+    LIBS.append('lzma')
+
+os.system('swig -python -c++ ./ctc_beam_search_decoder.i')
+
+ctc_beam_search_decoder_module = [
+    Extension(
+        name='_swig_ctc_beam_search_decoder',
+        sources=FILES + [
+            'scorer.cpp', 'ctc_beam_search_decoder_wrap.cxx',
+            'ctc_beam_search_decoder.cpp'
+        ],
+        language='C++',
+        include_dirs=['.'],
+        libraries=LIBS,
+        extra_compile_args=ARGS)
+]
+
+setup(
+    name='swig_ctc_beam_search_decoder',
+    version='0.1',
+    author='Yibing Liu',
+    description="""CTC beam search decoder""",
+    ext_modules=ctc_beam_search_decoder_module,
+    py_modules=['swig_ctc_beam_search_decoder'], )

deploy/scorer.cpp

+#include <iostream>
+
+#include "scorer.h"
+#include "lm/model.hh"
+#include "util/tokenize_piece.hh"
+#include "util/string_piece.hh"
+
+using namespace lm::ngram;
+
+Scorer::Scorer(float alpha, float beta, std::string lm_model_path) {
+    this->_alpha = alpha;
+    this->_beta = beta;
+    this->_language_model = new Model(lm_model_path.c_str());
+}
+
+Scorer::~Scorer(){
+   delete (Model *)this->_language_model;
+}
+
+inline void strip(std::string &str, char ch=' ') {
+    if (str.size() == 0) return;
+    int start  = 0;
+    int end = str.size()-1;
+    for (int i=0; i<str.size(); i++){
+        if (str[i] == ch) {
+            start ++;
+        } else {
+            break;
+        }
+    }
+    for (int i=str.size()-1; i>=0; i--) {
+        if  (str[i] == ch) {
+            end --;
+        } else {
+            break;
+        }
+    }
+    
+    if (start == 0 && end == str.size()-1) return;
+    if (start > end) {
+        std::string emp_str;
+        str = emp_str;
+    } else {
+        str = str.substr(start, end-start+1);
+    }
+}
+
+int Scorer::word_count(std::string sentence) {
+    strip(sentence);
+    int cnt = 0;
+    for (int i=0; i<sentence.size(); i++) {
+        if (sentence[i] == ' ' && sentence[i-1] != ' ') {
+            cnt ++;
+        }
+    }
+    if (cnt > 0) cnt ++;
+    return cnt;
+}
+
+double Scorer::language_model_score(std::string sentence) {
+    Model *model = (Model *)this->_language_model;
+    State state, out_state;
+    lm::FullScoreReturn ret;
+    state = model->BeginSentenceState();
+
+    for (util::TokenIter<util::SingleCharacter, true> it(sentence, ' '); it; ++it){
+        lm::WordIndex vocab = model->GetVocabulary().Index(*it);
+        ret = model->FullScore(state, vocab, out_state);
+        state = out_state;
+    }
+    double score = ret.prob; 
+    
+    return  pow(10, score);
+}
+
+double Scorer::get_score(std::string sentence) {
+    double lm_score = language_model_score(sentence);
+    int word_cnt = word_count(sentence);
+
+    double final_score = pow(lm_score, _alpha) * pow(word_cnt, _beta);
+    return final_score;
+}

deploy/scorer.h

+#ifndef SCORER_H_
+#define SCORER_H_
+
+#include <string>
+
+
+class Scorer{
+private:
+    float _alpha;
+    float _beta;
+    void *_language_model;
+
+public:
+    Scorer(){}
+    Scorer(float alpha, float beta, std::string lm_model_path);
+    ~Scorer();
+    int word_count(std::string);
+    double language_model_score(std::string);
+    double get_score(std::string);
+};
+
+#endif

deploy/scorer.i

+%module swig_scorer
+%{
+#include "scorer.h"
+%}
+
+%include "std_string.i"
+
+%include "scorer.h"

deploy/scorer_setup.py

+from setuptools import setup, Extension
+import glob
+import platform
+import os
+
+
+def compile_test(header, library):
+    dummy_path = os.path.join(os.path.dirname(__file__), "dummy")
+    command = "bash -c \"g++ -include " + header + " -l" + library + " -x c++ - <<<'int main() {}' -o " + dummy_path + " >/dev/null 2>/dev/null && rm " + dummy_path + " 2>/dev/null\""
+    return os.system(command) == 0
+
+
+FILES = glob.glob('util/*.cc') + glob.glob('lm/*.cc') + glob.glob(
+    'util/double-conversion/*.cc')
+FILES = [
+    fn for fn in FILES if not (fn.endswith('main.cc') or fn.endswith('test.cc'))
+]
+
+LIBS = ['stdc++']
+if platform.system() != 'Darwin':
+    LIBS.append('rt')
+
+ARGS = ['-O3', '-DNDEBUG', '-DKENLM_MAX_ORDER=6']
+
+if compile_test('zlib.h', 'z'):
+    ARGS.append('-DHAVE_ZLIB')
+    LIBS.append('z')
+
+if compile_test('bzlib.h', 'bz2'):
+    ARGS.append('-DHAVE_BZLIB')
+    LIBS.append('bz2')
+
+if compile_test('lzma.h', 'lzma'):
+    ARGS.append('-DHAVE_XZLIB')
+    LIBS.append('lzma')
+
+os.system('swig -python -c++ ./scorer.i')
+
+ext_modules = [
+    Extension(
+        name='_swig_scorer',
+        sources=FILES + ['scorer_wrap.cxx', 'scorer.cpp'],
+        language='C++',
+        include_dirs=['.'],
+        libraries=LIBS,
+        extra_compile_args=ARGS)
+]
+
+setup(
+    name='swig_scorer',
+    version='0.1',
+    ext_modules=ext_modules,
+    include_package_data=True,
+    py_modules=['swig_scorer'], )