ufal.nametag
============

The ``ufal.nametag`` is a Python binding to NameTag library <http://ufal.mff.cuni.cz/nametag>.

The bindings is a straightforward conversion of the ``C++`` bindings API.
In Python 2, strings can be both ``unicode`` and UTF-8 encoded ``str``, and the
library always produces ``unicode``. In Python 3, strings must be only ``str``.


Wrapped C++ API
---------------

The C++ API being wrapped follows. For a API reference of the original
C++ API, see <http://ufal.mff.cuni.cz/nametag/api-reference>.

::

  Helper Structures
  -----------------
  
    typedef vector<string> Forms;
  
    struct TokenRange {
      size_t start;
      size_t length;
    };
    typedef vector<TokenRange> TokenRanges;
  
    struct NamedEntity {
      size_t start;
      size_t length;
      string type;
  
      NamedEntity();
      NamedEntity(size_t start, size_t length, const string& type);
    };
    typedef vector<NamedEntity> NamedEntities;
  
  
  Main Classes
  ------------
  
    class Version {
     public:
      unsigned major;
      unsigned minor;
      unsigned patch;
      string prerelease;
  
      static Version current();
    };
  
    class Tokenizer {
     public:
      virtual void setText(const char* text);
      virtual bool nextSentence(Forms* forms, TokenRanges* tokens);
  
      static Tokenizer* newVerticalTokenizer();
    };
  
    class Ner {
      static ner* load(const char* fname);
  
      virtual void recognize(Forms& forms, NamedEntities& entities) const;
  
      virtual Tokenizer* newTokenizer() const;
    };


Examples
========

run_ner
-------

Simple example performing named entity recognition::

  import sys
  
  from ufal.nametag import *
  
  def encode_entities(text):
    return text.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;').replace('"', '&quot;')
  
  def sort_entities(entities):
    return sorted(entities, key=lambda entity: (entity.start, -entity.length))
  
  # In Python2, wrap sys.stdin and sys.stdout to work with unicode.
  if sys.version_info[0] < 3:
    import codecs
    import locale
    encoding = locale.getpreferredencoding()
    sys.stdin = codecs.getreader(encoding)(sys.stdin)
    sys.stdout = codecs.getwriter(encoding)(sys.stdout)
  
  if len(sys.argv) == 1:
    sys.stderr.write('Usage: %s recognizer_model\n' % sys.argv[0])
    sys.exit(1)
  
  sys.stderr.write('Loading ner: ')
  ner = Ner.load(sys.argv[1])
  if not ner:
    sys.stderr.write("Cannot load recognizer from file '%s'\n" % sys.argv[1])
    sys.exit(1)
  sys.stderr.write('done\n')
  
  forms = Forms()
  tokens = TokenRanges()
  entities = NamedEntities()
  sortedEntities = []
  openEntities = []
  tokenizer = ner.newTokenizer()
  if tokenizer is None:
    sys.stderr.write("No tokenizer is defined for the supplied model!")
    sys.exit(1)
  
  not_eof = True
  while not_eof:
    text = ''
  
    # Read block
    while True:
      line = sys.stdin.readline()
      not_eof = bool(line)
      if not not_eof: break
      line = line.rstrip('\r\n')
      text += line
      text += '\n';
      if not line: break
  
    # Tokenize and recognize
    tokenizer.setText(text)
    t = 0
    while tokenizer.nextSentence(forms, tokens):
      ner.recognize(forms, entities)
      sortedEntities = sort_entities(entities)
  
      # Write entities
      e = 0
      for i in range(len(tokens)):
        sys.stdout.write(encode_entities(text[t:tokens[i].start]))
        if (i == 0): sys.stdout.write("<sentence>")
  
        # Open entities starting at current token
        while (e < len(sortedEntities) and sortedEntities[e].start == i):
          sys.stdout.write('<ne type="%s">' % encode_entities(sortedEntities[e].type))
          openEntities.append(sortedEntities[e].start + sortedEntities[e].length - 1)
          e = e + 1
  
        # The token itself
        sys.stdout.write('<token>%s</token>' % encode_entities(text[tokens[i].start : tokens[i].start + tokens[i].length]))
  
        # Close entities ending after current token
        while openEntities and openEntities[-1] == i:
          sys.stdout.write('</ne>')
          openEntities.pop()
        if (i + 1 == len(tokens)): sys.stdout.write("</sentence>")
        t = tokens[i].start + tokens[i].length
    # Write rest of the text
    sys.stdout.write(encode_entities(text[t:]))


AUTHORS
=======

Milan Straka <straka@ufal.mff.cuni.cz>

Jana Straková <strakova@ufal.mff.cuni.cz>


COPYRIGHT AND LICENCE
=====================

Copyright 2016 Institute of Formal and Applied Linguistics, Faculty of
Mathematics and Physics, Charles University in Prague, Czech Republic.

This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
