Support alternative Wordnet versions

nltk/corpus/__init__.py

@@ -361,6 +361,9 @@
     WordNetCorpusReader,
     LazyCorpusLoader("omw", CorpusReader, r".*/wn-data-.*\.tab", encoding="utf8"),
 )
+wordnet31 = LazyCorpusLoader("wordnet31", WordNetCorpusReader, None)
+# wordnet2021 is scheduled for release in 2021 :)
+# wordnet2021 = LazyCorpusLoader("wordnet2021", WordNetCorpusReader, None)
 wordnet_ic = LazyCorpusLoader("wordnet_ic", WordNetICCorpusReader, r".*\.dat")
 words = LazyCorpusLoader(
     "words", WordListCorpusReader, r"(?!README|\.).*", encoding="ascii"

nltk/corpus/reader/wordnet.py

@@ -32,6 +32,7 @@
 
 import math
 import re
+import warnings
 from collections import defaultdict, deque
 from functools import total_ordering
 from itertools import chain, islice
@@ -1130,6 +1131,11 @@ def __init__(self, root, omw_reader):
         Construct a new wordnet corpus reader, with the given root
         directory.
         """
+        if omw_reader is None:
+            warnings.warn(
+                "The multilingual functions are not available with this Wordnet version"
+            )
+
         super().__init__(root, self._FILES, encoding=self._ENCODING)
 
         # A index that provides the file offset
@@ -1288,7 +1294,7 @@ def _compute_max_depth(self, pos, simulate_root):
     def get_version(self):
         fh = self._data_file(ADJ)
         for line in fh:
-            match = re.search(r"WordNet (\d+\.\d+) Copyright", line)
+            match = re.search(r"Word[nN]et (\d+|\d+\.\d+) Copyright", line)
             if match is not None:
                 version = match.group(1)
                 fh.seek(0)

nltk/test/wordnet.doctest

@@ -758,6 +758,27 @@ classified.a.02):
       [Synset('restricted.a.01'), [Synset('classified.a.02')]]]]
 
 
+----------------------------------------------------------------
+Loading alternative Wordnet versions
+----------------------------------------------------------------
+
+    >>> print("Wordnet {}".format(wn.get_version()))
+    Wordnet 3.0
+
+    >>> from nltk.corpus import wordnet31 as wn31
+    >>> print("Wordnet {}".format(wn31.get_version()))
+    Wordnet 3.1
+
+    >>> print(wn.synset('restrain.v.01').hyponyms())
+    [Synset('confine.v.03'), Synset('control.v.02'), Synset('hold.v.36'), Synset('inhibit.v.04')]
+
+    >>> print(wn31.synset('restrain.v.01').hyponyms())
+    [Synset('enchain.v.01'), Synset('fetter.v.01'), Synset('ground.v.02'), Synset('impound.v.02'), Synset('pen_up.v.01'), Synset('pinion.v.01'), Synset('pound.v.06'), Synset('tie_down.v.01')]
+
+    >>> print(wn31.synset('restrain.v.04').hyponyms())
+    [Synset('baffle.v.03'), Synset('confine.v.02'), Synset('control.v.02'), Synset('hold.v.36'), Synset('rule.v.07'), Synset('swallow.v.06'), Synset('wink.v.04')]
+
+
 -------------
 Teardown test
 -------------