Merge pull request #60 from mammo0/polyglot

use polyglot for language detection and transliteration

app/__init__.py

@@ -1,2 +1,10 @@
+import os
+from appdirs import user_data_dir
+
+# override polyglot path
+import polyglot
+polyglot.polyglot_path = os.path.join(user_data_dir(appname="LibreTranslate", appauthor="uav4geo"), "polyglot_data")
+
+
 from .main import main
 from .manage import manage

app/app.py

@@ -2,12 +2,9 @@ import os
 from flask import Flask, render_template, jsonify, request, abort, send_from_directory
 from flask_swagger import swagger
 from flask_swagger_ui import get_swaggerui_blueprint
-from langdetect import detect_langs
-from langdetect import DetectorFactory
 from pkg_resources import resource_filename
 from .api_keys import Database
-
-DetectorFactory.seed = 0 # deterministic
+from app.language import detect_languages, transliterate
 
 api_keys_db = None
 
@@ -57,11 +54,6 @@ def create_app(args):
     from app.language import languages
     app = Flask(__name__)
 
-    # For faster access
-    language_map = {}
-    for l in languages:
-        language_map[l.code] = l.name
-
     if args.debug:
         app.config['TEMPLATES_AUTO_RELOAD'] = True
 
@@ -271,19 +263,12 @@ def create_app(args):
               abort(400, description="Invalid request: Request (%d) exceeds character limit (%d)" % (chars, args.char_limit))
 
         if source_lang == 'auto':
-            candidate_langs = list(filter(lambda l: l.lang in language_map, detect_langs(q)))
-
-            if len(candidate_langs) > 0:
-                candidate_langs.sort(key=lambda l: l.prob, reverse=True)
+            candidate_langs = detect_languages(q)
 
             if args.debug:
                 print(candidate_langs)
 
-                source_lang = next(iter([l.code for l in languages if l.code == candidate_langs[0].lang]), None)
-                if not source_lang:
-                    source_lang = 'en'
-            else:
-                source_lang = 'en'
+            source_lang = candidate_langs[0]["language"]
 
             if args.debug:
                 print("Auto detected: %s" % source_lang)
@@ -300,9 +285,9 @@ def create_app(args):
 
         try:
           if batch:
-            return jsonify({"translatedText": [translator.translate(text) for text in q] })
+            return jsonify({"translatedText": [translator.translate(transliterate(text, target_lang=source_lang)) for text in q] })
           else:
-            return jsonify({"translatedText": translator.translate(q) })
+            return jsonify({"translatedText": translator.translate(transliterate(q, target_lang=source_lang)) })
         except Exception as e:
             abort(500, description="Cannot translate text: %s" % str(e))
 
@@ -385,12 +370,7 @@ def create_app(args):
         if not q:
             abort(400, description="Invalid request: missing q parameter")
 
-        candidate_langs = list(filter(lambda l: l.lang in language_map, detect_langs(q)))
-        candidate_langs.sort(key=lambda l: l.prob, reverse=True)
-        return jsonify([{
-            'confidence': l.prob,
-            'language': l.lang
-        } for l in candidate_langs])
+        return jsonify(detect_languages(q))
 
 
     @app.route("/frontend/settings")

app/init.py

@@ -2,9 +2,12 @@ import os
 from pathlib import Path
 from argostranslate import settings, package, translate
 import os, glob, shutil, zipfile
+from app.language import languages
+import polyglot
 
 def boot():
     check_and_install_models()
+    check_and_install_transliteration()
 
 def check_and_install_models(force=False):
     if len(package.get_installed_packages()) < 2 or force:
@@ -22,5 +25,32 @@ def check_and_install_models(force=False):
             download_path = available_package.download()
             package.install_from_path(download_path)
 
+        # reload installed languages
+        global languages
+        languages = translate.load_installed_languages()
         print("Loaded support for %s languages (%s models total)!" % (len(translate.load_installed_languages()), len(available_packages)))
 
+
+def check_and_install_transliteration(force=False):
+    # 'en' is not a supported transliteration language
+    transliteration_languages = [l.code for l in languages if l.code != "en"]
+
+    # check installed
+    install_needed = []
+    if not force:
+        t_packages_path = Path(polyglot.polyglot_path) / "transliteration2"
+        for lang in transliteration_languages:
+            if not (t_packages_path / lang / f"transliteration.{lang}.tar.bz2").exists():
+                install_needed.append(lang)
+    else:
+        install_needed = transliteration_languages
+
+    # install the needed transliteration packages
+    if install_needed:
+        print(f"Installing transliteration models for the following languages: {', '.join(install_needed)}")
+
+        from polyglot.downloader import Downloader
+        downloader = Downloader()
+
+        for lang in install_needed:
+            downloader.download(f"transliteration2.{lang}")

app/language.py

@@ -1,3 +1,124 @@
+import string
+
 from argostranslate import translate
+from polyglot.detect.base import Detector, UnknownLanguage
+from polyglot.transliteration.base import Transliterator
+
 
 languages = translate.load_installed_languages()
+
+
+__lang_codes = [l.code for l in languages]
+
+
+def detect_languages(text):
+    # detect batch processing
+    if isinstance(text, list):
+        is_batch = True
+    else:
+        is_batch = False
+        text = [text]
+
+    # get the candidates
+    candidates = []
+    for t in text:
+        try:
+            candidates.extend(Detector(t).languages)
+        except UnknownLanguage as e:
+            pass
+
+    # total read bytes of the provided text
+    read_bytes_total = sum(c.read_bytes for c in candidates)
+
+    # only use candidates that are supported by argostranslate
+    candidate_langs = list(filter(lambda l: l.read_bytes != 0 and l.code in __lang_codes, candidates))
+
+    # this happens if no language could be detected
+    if not candidate_langs:
+        # use language "en" by default but with zero confidence
+        return [
+                    {
+                        'confidence': 0.0,
+                        'language': "en"
+                    }
+                ]
+
+    # for multiple occurrences of the same language (can happen on batch detection)
+    # calculate the average confidence for each language
+    if is_batch:
+        temp_average_list = []
+        for lang_code in __lang_codes:
+            # get all candidates for a specific language
+            lc = list(filter(lambda l: l.code == lang_code, candidate_langs))
+            if len(lc) > 1:
+                # if more than one is present, calculate the average confidence
+                lang = lc[0]
+                lang.confidence = sum(l.confidence for l in lc) / len(lc)
+                lang.read_bytes = sum(l.read_bytes for l in lc)
+                temp_average_list.append(lang)
+            elif lc:
+                # otherwise just add it to the temporary list
+                temp_average_list.append(lc[0])
+
+        if temp_average_list:
+            # replace the list
+            candidate_langs = temp_average_list
+
+    # sort the candidates descending based on the detected confidence
+    candidate_langs.sort(key=lambda l: (l.confidence * l.read_bytes) / read_bytes_total, reverse=True)
+
+    return [
+                {
+                    'confidence': l.confidence,
+                    'language': l.code
+                }
+                for l in candidate_langs
+            ]
+
+
+def __transliterate_line(transliterator, line_text):
+    new_text = []
+
+    # transliteration is done word by word
+    for orig_word in line_text.split(" "):
+        # remove any punctuation on the right side
+        r_word = orig_word.rstrip(string.punctuation)
+        r_diff = set(char for char in orig_word) - set(char for char in r_word)
+        # and on the left side
+        l_word = orig_word.lstrip(string.punctuation)
+        l_diff = set(char for char in orig_word) - set(char for char in l_word)
+
+        # the actual transliteration of the word
+        t_word = transliterator.transliterate(orig_word.strip(string.punctuation))
+
+        # if transliteration fails, default back to the original word
+        if not t_word:
+            t_word = orig_word
+        else:
+            # add back any stripped punctuation
+            if r_diff:
+                t_word = t_word + ''.join(r_diff)
+            if l_diff:
+                t_word = ''.join(l_diff) + t_word
+
+        new_text.append(t_word)
+
+    # rebuild the text
+    return " ".join(new_text)
+
+
+def transliterate(text, target_lang="en"):
+    # initialize the transliterator from polyglot
+    transliterator = Transliterator(target_lang=target_lang)
+
+    # check for multiline string
+    if "\n" in text:
+        lines = []
+        # process each line separate
+        for line in text.split("\n"):
+            lines.append(__transliterate_line(transliterator, line))
+
+        # rejoin multiline string
+        return "\n".join(lines)
+    else:
+        return __transliterate_line(transliterator, text)

install_models.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 
-from app.init import check_and_install_models
+from app.init import check_and_install_models, check_and_install_transliteration
 
 if __name__ == "__main__":
 	check_and_install_models(force=True)
+	check_and_install_transliteration(force=True)

requirements.txt

@@ -4,5 +4,9 @@ flask-swagger==0.2.14
 flask-swagger-ui==3.36.0
 Flask-Limiter==1.4
 waitress==1.4.4
-langdetect==1.0.8
 expiringdict==1.2.1
+pyicu==2.6
+pycld2==0.41
+morfessor==2.0.6
+polyglot==16.7.4
+appdirs==1.4.4