code cleanup for the deployment decoder

deploy/ctc_beam_search_decoder.cpp

@@ -6,35 +6,47 @@
 #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) {
+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) {
+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
-                                  )
-{
+    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) {
+    // dimension check
     int num_time_steps = probs_seq.size();
+    for (int i=0; i<num_time_steps; i++) {
+        if (probs_seq[i].size() != vocabulary.size()+1) {
+            std::cout<<"The shape of probs_seq does not match"
+                     <<" with the shape of the vocabulary!"<<std::endl;
+            exit(1);
+        }
+    }
+
+    // blank_id check
+    if (blank_id > vocabulary.size()) {
+        std::cout<<"Invalid blank_id!"<<std::endl;
+        exit(1);
+    }
 
     // assign space ID
-    std::vector<std::string>::iterator it = std::find(vocabulary.begin(), vocabulary.end(), " ");
-    int space_id = it-vocabulary.begin();
+    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!";
+        std::cout<<"The character space is not in the vocabulary!"<<std::endl;
         exit(1);
     }
 
@@ -60,7 +72,8 @@ std::vector<std::pair<double, std::string> >
         }
         // pruning of vacobulary
         if (cutoff_prob < 1.0) {
-            std::sort(prob_idx.begin(), prob_idx.end(), pair_comp_second_rev<int, double>);
+            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++) {
@@ -68,7 +81,8 @@ std::vector<std::pair<double, std::string> >
                 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);
+            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();
@@ -82,11 +96,11 @@ std::vector<std::pair<double, std::string> >
                 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]);
+                    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;
+                    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;
@@ -105,19 +119,22 @@ std::vector<std::pair<double, std::string> >
                         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_plus] = probs_nb_cur[l_plus] + probs_b_cur[l_plus];
                 }
             }
 
-            prefix_set_next[l] = probs_b_cur[l]+probs_nb_cur[l];
+            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_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);
     }
@@ -138,6 +155,7 @@ std::vector<std::pair<double, std::string> >
         }
     }
     // sort the result and return
-    std::sort(beam_result.begin(), beam_result.end(), pair_comp_first_rev<double, std::string>);
+    std::sort(beam_result.begin(), beam_result.end(),
+              pair_comp_first_rev<double, std::string>);
     return beam_result;
 }

deploy/ctc_beam_search_decoder.h

@@ -6,14 +6,30 @@
 #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
-                                  );
+/* CTC Beam Search Decoder, the interface is consistent with the
+ * original decoder in Python version.
+
+ * Parameters:
+ *     probs_seq: 2-D vector that each element is a vector of probabilities
+ *               over vocabulary of one time step.
+ *     beam_size: The width of beam search.
+ *     vocabulary: A vector of vocabulary.
+ *     blank_id: ID of blank.
+ *     cutoff_prob: Cutoff probability of pruning
+ *     ext_scorer: External scorer to evaluate a prefix.
+ *     nproc: Whether this function used in multiprocessing.
+ * Return:
+ *     A vector that each element is a pair of score  and decoding result,
+ *     in desending order.
+*/
+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=1.0,
+                            Scorer *ext_scorer=NULL,
+                            bool nproc=false
+                            );
 
 #endif // CTC_BEAM_SEARCH_DECODER_H_

deploy/decoder_setup.py

@@ -10,8 +10,8 @@ def compile_test(header, library):
     return os.system(command) == 0
 
 
-FILES = glob.glob('util/*.cc') + glob.glob('lm/*.cc') + glob.glob(
-    'util/double-conversion/*.cc')
+FILES = glob.glob('kenlm/util/*.cc') + glob.glob('kenlm/lm/*.cc') + glob.glob(
+    'kenlm/util/double-conversion/*.cc')
 FILES = [
     fn for fn in FILES if not (fn.endswith('main.cc') or fn.endswith('test.cc'))
 ]
@@ -44,7 +44,7 @@ ctc_beam_search_decoder_module = [
             'ctc_beam_search_decoder.cpp'
         ],
         language='C++',
-        include_dirs=['.'],
+        include_dirs=['.', './kenlm'],
         libraries=LIBS,
         extra_compile_args=ARGS)
 ]
@@ -52,7 +52,6 @@ ctc_beam_search_decoder_module = [
 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"
@@ -17,6 +16,13 @@ Scorer::~Scorer(){
    delete (Model *)this->_language_model;
 }
 
+/* Strip a input sentence
+ * Parameters:
+ *     str: A reference to the objective string
+ *     ch: The character to prune
+ * Return:
+ *     void
+ */
 inline void strip(std::string &str, char ch=' ') {
     if (str.size() == 0) return;
     int start  = 0;
@@ -69,10 +75,14 @@ double Scorer::language_model_score(std::string sentence) {
     }
     //log10 prob
     double log_prob = ret.prob;
-
     return log_prob;
 }
 
+void Scorer::reset_params(float alpha, float beta) {
+    this->_alpha = alpha;
+    this->_beta = beta;
+}
+
 double Scorer::get_score(std::string sentence) {
     double lm_score = language_model_score(sentence);
     int word_cnt = word_count(sentence);

deploy/scorer.h

@@ -3,20 +3,34 @@
 
 #include <string>
 
+/* External scorer to evaluate a prefix or a complete sentence
+ * when a new word appended during decoding, consisting of word
+ * count and language model scoring.
 
+ * Example:
+ *     Scorer ext_scorer(alpha, beta, "path_to_language_model.klm");
+ *     double score = ext_scorer.get_score("sentence_to_score");
+ */
 class Scorer{
 private:
     float _alpha;
     float _beta;
     void *_language_model;
 
+    // word insertion term
+    int word_count(std::string);
+    // n-gram language model scoring
+    double language_model_score(std::string);
+
 public:
     Scorer(){}
     Scorer(float alpha, float beta, std::string lm_model_path);
     ~Scorer();
-    int word_count(std::string);
-    double language_model_score(std::string);
+
+    // reset params alpha & beta
+    void reset_params(float alpha, float beta);
+    // get the final score
     double get_score(std::string);
 };
 
-#endif
+#endif //SCORER_H_

deploy/scorer_setup.py

@@ -10,8 +10,8 @@ def compile_test(header, library):
     return os.system(command) == 0
 
 
-FILES = glob.glob('util/*.cc') + glob.glob('lm/*.cc') + glob.glob(
-    'util/double-conversion/*.cc')
+FILES = glob.glob('kenlm/util/*.cc') + glob.glob('kenlm/lm/*.cc') + glob.glob(
+    'kenlm/util/double-conversion/*.cc')
 FILES = [
     fn for fn in FILES if not (fn.endswith('main.cc') or fn.endswith('test.cc'))
 ]
@@ -41,7 +41,7 @@ ext_modules = [
         name='_swig_scorer',
         sources=FILES + ['scorer_wrap.cxx', 'scorer.cpp'],
         language='C++',
-        include_dirs=['.'],
+        include_dirs=['.', './kenlm'],
         libraries=LIBS,
         extra_compile_args=ARGS)
 ]