Add generate_package tool to create combined scorer package

data/lm/generate_package.py

@@ -0,0 +1,120 @@
+#!/usr/bin/env python
+from __future__ import absolute_import, division, print_function
+
+# Make sure we can import stuff from util/
+# This script needs to be run from the root of the DeepSpeech repository
+import os
+import sys
+sys.path.insert(1, os.path.join(sys.path[0], '..', '..'))
+
+import argparse
+import shutil
+
+from util.text import Alphabet, UTF8Alphabet
+from ds_ctcdecoder import Scorer, Alphabet as NativeAlphabet
+
+
+def create_bundle(alphabet_path, lm_path, vocab_path, package_path, force_utf8):
+    words = set()
+    vocab_looks_char_based = True
+    with open(vocab_path) as fin:
+        for line in fin:
+            for word in line.split():
+                words.add(word.encode('utf-8'))
+                if len(word) > 1:
+                    vocab_looks_char_based = False
+    print("{} unique words read from vocabulary file.".format(len(words)))
+    print(
+        "{} like a character based model.".format(
+            "Looks" if vocab_looks_char_based else "Doesn't look"
+        )
+    )
+
+    if force_utf8 != None:
+        use_utf8 = force_utf8.value
+    else:
+        use_utf8 = vocab_looks_char_based
+
+    if use_utf8:
+        serialized_alphabet = UTF8Alphabet().serialize()
+    else:
+        serialized_alphabet = Alphabet(alphabet_path).serialize()
+
+    alphabet = NativeAlphabet()
+    err = alphabet.deserialize(serialized_alphabet, len(serialized_alphabet))
+    if err != 0:
+        print("Error loading alphabet: {}".format(err))
+        sys.exit(1)
+
+    scorer = Scorer()
+    scorer.set_alphabet(alphabet)
+    scorer.set_utf8_mode(use_utf8)
+    scorer.load_lm(lm_path, "")
+    scorer.fill_dictionary(list(words))
+    shutil.copy(lm_path, package_path)
+    scorer.save_dictionary(package_path, True) # append, not overwrite
+    print('Package created in {}'.format(package_path))
+
+
+class Tristate(object):
+    def __init__(self, value=None):
+       if any(value is v for v in (True, False, None)):
+          self.value = value
+       else:
+           raise ValueError("Tristate value must be True, False, or None")
+
+    def __eq__(self, other):
+       return (self.value is other.value if isinstance(other, Tristate)
+               else self.value is other)
+
+    def __ne__(self, other):
+       return not self == other
+
+    def __bool__(self):
+       raise TypeError("Tristate object may not be used as a Boolean")
+
+    def __str__(self):
+        return str(self.value)
+
+    def __repr__(self):
+        return "Tristate(%s)" % self.value
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Generate an external scorer package for DeepSpeech."
+    )
+    parser.add_argument(
+        "--alphabet",
+        help="Path of alphabet file to use for vocabulary construction. Words with characters not in the alphabet will not be included in the vocabulary. Optional if using UTF-8 mode.",
+    )
+    parser.add_argument(
+        "--lm",
+        required=True,
+        help="Path of KenLM binary LM file. Must be built without including the vocabulary (use the -v flag). See generate_lm.py for how to create a binary LM.",
+    )
+    parser.add_argument(
+        "--vocab",
+        required=True,
+        help="Path of vocabulary file. Must contain words separated by whitespace.",
+    )
+    parser.add_argument("--package", required=True, help="Path to save scorer package.")
+    parser.add_argument(
+        "--force_utf8",
+        default="",
+        help="Boolean flag, force set or unset UTF-8 mode in the scorer package. If not set, infers from the vocabulary.",
+    )
+    args = parser.parse_args()
+
+    if args.force_utf8 in ("True", "1", "true", "yes", "y"):
+        force_utf8 = Tristate(True)
+    elif args.force_utf8 in ("False", "0", "false", "no", "n"):
+        force_utf8 = Tristate(False)
+    else:
+        force_utf8 = Tristate(None)
+
+    create_bundle(args.alphabet, args.lm, args.vocab, args.package, force_utf8)
+
+
+if __name__ == "__main__":
+    main()

native_client/ctcdecode/__init__.py

@@ -17,8 +17,10 @@ class Scorer(swigwrapper.Scorer):
     :alphabet: Alphabet
     :type model_path: basestring
     """
-    def __init__(self, alpha, beta, model_path, trie_path, alphabet):
+    def __init__(self, alpha=None, beta=None, model_path=None, trie_path=None, alphabet=None):
         super(Scorer, self).__init__()
+        # Allow bare initialization
+        if alphabet:
             serialized = alphabet.serialize()
             native_alphabet = swigwrapper.Alphabet()
             err = native_alphabet.deserialize(serialized, len(serialized))
@@ -32,14 +34,11 @@ class Scorer(swigwrapper.Scorer):
             if err != 0:
                 raise ValueError("Scorer initialization failed with error code {}".format(err), err)
 
-    def __init__(self):
-        super(Scorer, self).__init__()
-
     def load_lm(self, lm_path, trie_path):
         super(Scorer, self).load_lm(lm_path.encode('utf-8'), trie_path.encode('utf-8'))
 
-    def save_dictionary(self, save_path):
+    def save_dictionary(self, save_path, *args, **kwargs):
-        super(Scorer, self).save_dictionary(save_path.encode('utf-8'))
+        super(Scorer, self).save_dictionary(save_path.encode('utf-8'), *args, **kwargs)
 
 
 def ctc_beam_search_decoder(probs_seq,

native_client/ctcdecode/scorer.cpp

@@ -128,9 +128,15 @@ void Scorer::load_lm(const std::string& lm_path, const std::string& trie_path)
   max_order_ = language_model_->Order();
 }
 
-void Scorer::save_dictionary(const std::string& path)
+void Scorer::save_dictionary(const std::string& path, bool append_instead_of_overwrite)
 {
-  std::fstream fout(path, std::ios::in|std::ios::out|std::ios::binary|std::ios::ate);
+  std::ios::openmode om;
+  if (append_instead_of_overwrite) {
+    om = std::ios::in|std::ios::out|std::ios::binary|std::ios::ate;
+  } else {
+    om = std::ios::out|std::ios::binary;
+  }
+  std::fstream fout(path, om);
   fout.write(reinterpret_cast<const char*>(&MAGIC), sizeof(MAGIC));
   fout.write(reinterpret_cast<const char*>(&FILE_VERSION), sizeof(FILE_VERSION));
   fout.write(reinterpret_cast<const char*>(&is_utf8_mode_), sizeof(is_utf8_mode_));

native_client/ctcdecode/scorer.h

@@ -95,7 +95,7 @@ public:
   void set_alphabet(const Alphabet& alphabet);
 
   // save dictionary in file
-  void save_dictionary(const std::string &path);
+  void save_dictionary(const std::string &path, bool append_instead_of_overwrite=false);
 
   // return weather this step represents a boundary where beam scoring should happen
   bool is_scoring_boundary(PathTrie* prefix, size_t new_label);