refine the interface of decoders in swig

deploy.py

@@ -10,8 +10,8 @@ import multiprocessing
 import paddle.v2 as paddle
 from data_utils.data import DataGenerator
 from model import deep_speech2
-from swig_ctc_beam_search_decoder import *
-from swig_scorer import Scorer
+from deploy.swig_decoders import *
+from swig_scorer import LmScorer
 from error_rate import wer
 import utils
 import time
@@ -85,7 +85,7 @@ parser.add_argument(
     help="Number of output per sample in beam search. (default: %(default)d)")
 parser.add_argument(
     "--language_model_path",
-    default="lm/data/en.00.UNKNOWN.klm",
+    default="lm/data/common_crawl_00.prune01111.trie.klm",
     type=str,
     help="Path for language model. (default: %(default)s)")
 parser.add_argument(
@@ -164,19 +164,19 @@ def infer():
     ]
 
     # external scorer
-    ext_scorer = Scorer(args.alpha, args.beta, args.language_model_path)
+    ext_scorer = LmScorer(args.alpha, args.beta, args.language_model_path)
 
     ## decode and print
     time_begin = time.time()
     wer_sum, wer_counter = 0, 0
     for i, probs in enumerate(probs_split):
         beam_result = ctc_beam_search_decoder(
-            probs.tolist(),
-            args.beam_size,
-            data_generator.vocab_list,
-            len(data_generator.vocab_list),
-            args.cutoff_prob,
-            ext_scorer, )
+            probs_seq=probs,
+            beam_size=args.beam_size,
+            vocabulary=data_generator.vocab_list,
+            blank_id=len(data_generator.vocab_list),
+            cutoff_prob=args.cutoff_prob,
+            ext_scoring_func=ext_scorer, )
 
         print("\nTarget Transcription:\t%s" % target_transcription[i])
         print("Beam %d: %f \t%s" % (0, beam_result[0][0], beam_result[0][1]))

deploy/ctc_decoders.cpp

@@ -4,9 +4,9 @@
 #include <utility>
 #include <cmath>
 #include <limits>
-#include "ctc_beam_search_decoder.h"
+#include "ctc_decoders.h"
 
-typedef float log_prob_type;
+typedef double log_prob_type;
 
 template <typename T1, typename T2>
 bool pair_comp_first_rev(const std::pair<T1, T2> a, const std::pair<T1, T2> b)
@@ -24,8 +24,8 @@ template <typename T>
 T log_sum_exp(T x, T y)
 {
     static T num_min = -std::numeric_limits<T>::max();
-    if (x <= -num_min) return y;
-    if (y <= -num_min) return x;
+    if (x <= num_min) return y;
+    if (y <= num_min) return x;
     T xmax = std::max(x, y);
     return std::log(std::exp(x-xmax) + std::exp(y-xmax)) + xmax;
 }
@@ -55,17 +55,13 @@ std::string ctc_best_path_decoder(std::vector<std::vector<double> > probs_seq,
             }
         }
         max_idx_vec.push_back(max_idx);
-        std::cout<<max_idx<<",";
         max_prob = 0.0;
         max_idx = 0;
     }
-    std::cout<<std::endl;
 
     std::vector<int> idx_vec;
     for (int i=0; i<max_idx_vec.size(); i++) {
-        std::cout<<max_idx_vec[i]<<",";
         if ((i == 0) || ((i>0) && max_idx_vec[i]!=max_idx_vec[i-1])) {
-            std::cout<<max_idx_vec[i]<<",";
             idx_vec.push_back(max_idx_vec[i]);
         }
     }
@@ -73,7 +69,7 @@ std::string ctc_best_path_decoder(std::vector<std::vector<double> > probs_seq,
     std::string best_path_result;
     for (int i=0; i<idx_vec.size(); i++) {
         if (idx_vec[i] != blank_id) {
-            best_path_result += vocabulary[i];
+            best_path_result += vocabulary[idx_vec[i]];
         }
     }
     return best_path_result;
@@ -85,21 +81,21 @@ std::vector<std::pair<double, std::string> >
                             std::vector<std::string> vocabulary,
                             int blank_id,
                             double cutoff_prob,
-                            Scorer *ext_scorer,
+                            LmScorer *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;
+            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;
+        std::cout << " Invalid blank_id! " << std::endl;
         exit(1);
     }
 
@@ -108,7 +104,7 @@ std::vector<std::pair<double, std::string> >
                                                   vocabulary.end(), " ");
     int space_id = it - vocabulary.begin();
     if(space_id >= vocabulary.size()) {
-        std::cout<<"The character space is not in the vocabulary!"<<std::endl;
+        std::cout << " The character space is not in the vocabulary!"<<std::endl;
         exit(1);
     }
 

deploy/ctc_decoders.h

@@ -28,10 +28,19 @@ std::vector<std::pair<double, std::string> >
                             std::vector<std::string> vocabulary,
                             int blank_id,
                             double cutoff_prob=1.0,
-                            Scorer *ext_scorer=NULL,
+                            LmScorer *ext_scorer=NULL,
                             bool nproc=false
                             );
+
 /* CTC Best Path Decoder
+ *
+ * Parameters:
+ *     probs_seq: 2-D vector that each element is a vector of probabilities
+ *               over vocabulary of one time step.
+ *     vocabulary: A vector of vocabulary.
+ * Return:
+ *     A vector that each element is a pair of score  and decoding result,
+ *     in desending order.
  */
 std::string ctc_best_path_decoder(std::vector<std::vector<double> > probs_seq,
                                      std::vector<std::string> vocabulary);

deploy/ctc_decoders.i

@@ -1,6 +1,6 @@
-%module swig_ctc_beam_search_decoder
+%module swig_ctc_decoders
 %{
-#include "ctc_beam_search_decoder.h"
+#include "ctc_decoders.h"
 %}
 
 %include "std_vector.i"
@@ -19,4 +19,4 @@ namespace std{
 }
 
 %import scorer.h
-%include "ctc_beam_search_decoder.h"
+%include "ctc_decoders.h"

deploy/decoder_setup.py

@@ -34,15 +34,13 @@ if compile_test('lzma.h', 'lzma'):
     ARGS.append('-DHAVE_XZLIB')
     LIBS.append('lzma')
 
-os.system('swig -python -c++ ./ctc_beam_search_decoder.i')
+os.system('swig -python -c++ ./ctc_decoders.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'
-        ],
+        name='_swig_ctc_decoders',
+        sources=FILES +
+        ['scorer.cpp', 'ctc_decoders_wrap.cxx', 'ctc_decoders.cpp'],
         language='C++',
         include_dirs=['.', './kenlm'],
         libraries=LIBS,
@@ -50,8 +48,8 @@ ctc_beam_search_decoder_module = [
 ]
 
 setup(
-    name='swig_ctc_beam_search_decoder',
+    name='swig_ctc_decoders',
     version='0.1',
-    description="""CTC beam search decoder""",
+    description="""CTC decoders""",
     ext_modules=ctc_beam_search_decoder_module,
-    py_modules=['swig_ctc_beam_search_decoder'], )
+    py_modules=['swig_ctc_decoders'], )

deploy/scorer.cpp

@@ -7,7 +7,7 @@
 
 using namespace lm::ngram;
 
-Scorer::Scorer(float alpha, float beta, std::string lm_model_path) {
+LmScorer::LmScorer(float alpha, float beta, std::string lm_model_path) {
     this->_alpha = alpha;
     this->_beta = beta;
 
@@ -18,7 +18,7 @@ Scorer::Scorer(float alpha, float beta, std::string lm_model_path) {
     this->_language_model = LoadVirtual(lm_model_path.c_str());
 }
 
-Scorer::~Scorer(){
+LmScorer::~LmScorer(){
    delete (lm::base::Model *)this->_language_model;
 }
 
@@ -57,7 +57,7 @@ inline void strip(std::string &str, char ch=' ') {
     }
 }
 
-int Scorer::word_count(std::string sentence) {
+int LmScorer::word_count(std::string sentence) {
     strip(sentence);
     int cnt = 1;
     for (int i=0; i<sentence.size(); i++) {
@@ -68,7 +68,7 @@ int Scorer::word_count(std::string sentence) {
     return cnt;
 }
 
-double Scorer::language_model_score(std::string sentence) {
+double LmScorer::language_model_score(std::string sentence) {
     lm::base::Model *model = (lm::base::Model *)this->_language_model;
     State state, out_state;
     lm::FullScoreReturn ret;
@@ -84,12 +84,12 @@ double Scorer::language_model_score(std::string sentence) {
     return log_prob;
 }
 
-void Scorer::reset_params(float alpha, float beta) {
+void LmScorer::reset_params(float alpha, float beta) {
     this->_alpha = alpha;
     this->_beta = beta;
 }
 
-double Scorer::get_score(std::string sentence, bool log) {
+double LmScorer::get_score(std::string sentence, bool log) {
     double lm_score = language_model_score(sentence);
     int word_cnt = word_count(sentence);
 

deploy/scorer.h

@@ -8,10 +8,10 @@
  * count and language model scoring.
 
  * Example:
- *     Scorer ext_scorer(alpha, beta, "path_to_language_model.klm");
+ *     LmScorer ext_scorer(alpha, beta, "path_to_language_model.klm");
  *     double score = ext_scorer.get_score("sentence_to_score");
  */
-class Scorer{
+class LmScorer{
 private:
     float _alpha;
     float _beta;
@@ -23,9 +23,9 @@ private:
     double language_model_score(std::string);
 
 public:
-    Scorer(){}
-    Scorer(float alpha, float beta, std::string lm_model_path);
-    ~Scorer();
+    LmScorer(){}
+    LmScorer(float alpha, float beta, std::string lm_model_path);
+    ~LmScorer();
 
     // reset params alpha & beta
     void reset_params(float alpha, float beta);

deploy/swig_decoders.py

@@ -0,0 +1,86 @@
+"""Wrapper for various CTC decoders in SWIG."""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import swig_ctc_decoders
+import multiprocessing
+
+
+def ctc_best_path_decoder(probs_seq, vocabulary):
+    """Wrapper for ctc best path decoder in swig.
+
+    :param probs_seq: 2-D list of probability distributions over each time
+                      step, with each element being a list of normalized
+                      probabilities over vocabulary and blank.
+    :type probs_seq: 2-D list
+    :param vocabulary: Vocabulary list.
+    :type vocabulary: list
+    :return: Decoding result string.
+    :rtype: basestring
+    """
+    return swig_ctc_decoders.ctc_best_path_decoder(probs_seq.tolist(),
+                                                   vocabulary)
+
+
+def ctc_beam_search_decoder(
+        probs_seq,
+        beam_size,
+        vocabulary,
+        blank_id,
+        cutoff_prob=1.0,
+        ext_scoring_func=None, ):
+    """Wrapper for CTC Beam Search Decoder.
+
+    :param probs_seq: 2-D list of probability distributions over each time
+                      step, with each element being a list of normalized
+                      probabilities over vocabulary and blank.
+    :type probs_seq: 2-D list
+    :param beam_size: Width for beam search.
+    :type beam_size: int
+    :param vocabulary: Vocabulary list.
+    :type vocabulary: list
+    :param blank_id: ID of blank.
+    :type blank_id: int
+    :param cutoff_prob: Cutoff probability in pruning,
+                        default 1.0, no pruning.
+    :type cutoff_prob: float
+    :param ext_scoring_func: External scoring function for
+                            partially decoded sentence, e.g. word count
+                            or language model.
+    :type external_scoring_func: callable
+    :return: List of tuples of log probability and sentence as decoding
+             results, in descending order of the probability.
+    :rtype: list
+    """
+    return swig_ctc_decoders.ctc_beam_search_decoder(
+        probs_seq.tolist(), beam_size, vocabulary, blank_id, cutoff_prob,
+        ext_scoring_func)
+
+
+def ctc_beam_search_decoder_batch(probs_split,
+                                  beam_size,
+                                  vocabulary,
+                                  blank_id,
+                                  num_processes,
+                                  cutoff_prob=1.0,
+                                  ext_scoring_func=None):
+    """Wrapper for CTC beam search decoder in batch
+    """
+
+    # TODO: to resolve PicklingError
+
+    if not num_processes > 0:
+        raise ValueError("Number of processes must be positive!")
+
+    pool = multiprocessing.Pool(processes=num_processes)
+    results = []
+    for i, probs_list in enumerate(probs_split):
+        args = (probs_list, beam_size, vocabulary, blank_id, cutoff_prob,
+                ext_scoring_func)
+        results.append(pool.apply_async(ctc_beam_search_decoder, args))
+
+    pool.close()
+    pool.join()
+    beam_search_results = [result.get() for result in results]
+    return beam_search_results