Repository: piskvorky/gensim

Issue:
Threre is no support for online learning in poincare model
gensim supports online learning via `build_vocab` in fasttex, word2vec or other models.
But there is not `build_vocab` in poincare model.
Don't we need this mehotd or is it impossible to implement this feature ?



Discussion:

Resolving patch:
diff --git a/gensim/models/poincare.py b/gensim/models/poincare.py
--- a/gensim/models/poincare.py
+++ b/gensim/models/poincare.py
@@ -153,6 +153,10 @@ def __init__(self, train_data, size=50, alpha=0.1, negative=10, workers=1, epsil
         """
         self.train_data = train_data
         self.kv = PoincareKeyedVectors(size)
+        self.all_relations = []
+        self.node_relations = defaultdict(set)
+        self._negatives_buffer = NegativesBuffer([])
+        self._negatives_buffer_size = 2000
         self.size = size
         self.train_alpha = alpha  # Learning rate for training
         self.burn_in_alpha = burn_in_alpha  # Learning rate for burn-in
@@ -168,47 +172,81 @@ def __init__(self, train_data, size=50, alpha=0.1, negative=10, workers=1, epsil
         self._np_random = np_random.RandomState(seed)
         self.init_range = init_range
         self._loss_grad = None
-        self._load_relations()
-        self._init_embeddings()
+        self.build_vocab(train_data)
+
+    def build_vocab(self, relations, update=False):
+        """Build the model's vocabulary from known relations.
 
-    def _load_relations(self):
-        """Load relations from the train data and build vocab."""
-        vocab = {}
-        index2word = []
-        all_relations = []  # List of all relation pairs
-        node_relations = defaultdict(set)  # Mapping from node index to its related node indices
+        Parameters
+        ----------
+        relations : {iterable of (str, str), :class:`gensim.models.poincare.PoincareRelations`}
+            Iterable of relations, e.g. a list of tuples, or a :class:`gensim.models.poincare.PoincareRelations`
+            instance streaming from a file. Note that the relations are treated as ordered pairs,
+            i.e. a relation (a, b) does not imply the opposite relation (b, a). In case the relations are symmetric,
+            the data should contain both relations (a, b) and (b, a).
+        update : bool, optional
+            If true, only new nodes's embeddings are initialized.
+            Use this when the model already has an existing vocabulary and you want to update it.
+            If false, all node's embeddings are initialized.
+            Use this when you're creating a new vocabulary from scratch.
+
+        Examples
+        --------
+        Train a model and update vocab for online training:
+
+        .. sourcecode:: pycon
+
+            >>> from gensim.models.poincare import PoincareModel
+            >>>
+            >>> # train a new model from initial data
+            >>> initial_relations = [('kangaroo', 'marsupial'), ('kangaroo', 'mammal')]
+            >>> model = PoincareModel(initial_relations, negative=1)
+            >>> model.train(epochs=50)
+            >>>
+            >>> # online training: update the vocabulary and continue training
+            >>> online_relations = [('striped_skunk', 'mammal')]
+            >>> model.build_vocab(online_relations, update=True)
+            >>> model.train(epochs=50)
+
+        """
+        old_index2word_len = len(self.kv.index2word)
 
         logger.info("loading relations from train data..")
-        for relation in self.train_data:
+        for relation in relations:
             if len(relation) != 2:
                 raise ValueError('Relation pair "%s" should have exactly two items' % repr(relation))
             for item in relation:
-                if item in vocab:
-                    vocab[item].count += 1
+                if item in self.kv.vocab:
+                    self.kv.vocab[item].count += 1
                 else:
-                    vocab[item] = Vocab(count=1, index=len(index2word))
-                    index2word.append(item)
+                    self.kv.vocab[item] = Vocab(count=1, index=len(self.kv.index2word))
+                    self.kv.index2word.append(item)
             node_1, node_2 = relation
-            node_1_index, node_2_index = vocab[node_1].index, vocab[node_2].index
-            node_relations[node_1_index].add(node_2_index)
+            node_1_index, node_2_index = self.kv.vocab[node_1].index, self.kv.vocab[node_2].index
+            self.node_relations[node_1_index].add(node_2_index)
             relation = (node_1_index, node_2_index)
-            all_relations.append(relation)
-        logger.info("loaded %d relations from train data, %d nodes", len(all_relations), len(vocab))
-        self.kv.vocab = vocab
-        self.kv.index2word = index2word
-        self.indices_set = set(range(len(index2word)))  # Set of all node indices
-        self.indices_array = np.fromiter(range(len(index2word)), dtype=int)  # Numpy array of all node indices
-        self.all_relations = all_relations
-        self.node_relations = node_relations
+            self.all_relations.append(relation)
+        logger.info("loaded %d relations from train data, %d nodes", len(self.all_relations), len(self.kv.vocab))
+        self.indices_set = set(range(len(self.kv.index2word)))  # Set of all node indices
+        self.indices_array = np.fromiter(range(len(self.kv.index2word)), dtype=int)  # Numpy array of all node indices
         self._init_node_probabilities()
-        self._negatives_buffer = NegativesBuffer([])  # Buffer for negative samples, to reduce calls to sampling method
-        self._negatives_buffer_size = 2000
+
+        if not update:
+            self._init_embeddings()
+        else:
+            self._update_embeddings(old_index2word_len)
 
     def _init_embeddings(self):
         """Randomly initialize vectors for the items in the vocab."""
         shape = (len(self.kv.index2word), self.size)
         self.kv.syn0 = self._np_random.uniform(self.init_range[0], self.init_range[1], shape).astype(self.dtype)
 
+    def _update_embeddings(self, old_index2word_len):
+        """Randomly initialize vectors for the items in the additional vocab."""
+        shape = (len(self.kv.index2word) - old_index2word_len, self.size)
+        v = self._np_random.uniform(self.init_range[0], self.init_range[1], shape).astype(self.dtype)
+        self.kv.syn0 = np.concatenate([self.kv.syn0, v])
+
     def _init_node_probabilities(self):
         """Initialize a-priori probabilities."""
         counts = np.fromiter((
@@ -830,6 +868,7 @@ def __init__(self, vector_size):
         super(PoincareKeyedVectors, self).__init__(vector_size)
         self.max_distance = 0
         self.index2word = []
+        self.vocab = {}
 
     @property
     def vectors(self):


Test patch:
diff --git a/gensim/test/test_poincare.py b/gensim/test/test_poincare.py
--- a/gensim/test/test_poincare.py
+++ b/gensim/test/test_poincare.py
@@ -93,6 +93,16 @@ def test_persistence_separate_file(self):
         loaded = PoincareModel.load(testfile())
         self.models_equal(model, loaded)
 
+    def test_online_learning(self):
+        """Tests whether additional input data is loaded correctly and completely."""
+        model = PoincareModel(self.data, burn_in=0, negative=3)
+        self.assertEqual(len(model.kv.vocab), 7)
+        self.assertEqual(model.kv.vocab['kangaroo.n.01'].count, 3)
+        self.assertEqual(model.kv.vocab['cat.n.01'].count, 1)
+        model.build_vocab([('kangaroo.n.01', 'cat.n.01')], update=True)  # update vocab
+        self.assertEqual(model.kv.vocab['kangaroo.n.01'].count, 4)
+        self.assertEqual(model.kv.vocab['cat.n.01'].count, 2)
+
     def test_train_after_load(self):
         """Tests whether the model can be trained correctly after loading from disk."""
         model = PoincareModel(self.data, burn_in=0, negative=3)