* Begin revising tagger, focussing on POS tagging

spacy/tagger.pxd

@@ -5,20 +5,17 @@ from thinc.features cimport Extractor
 from thinc.typedefs cimport atom_t, feat_t, weight_t, class_t
 
 from .typedefs cimport hash_t
-from .context cimport Slots
 from .tokens cimport Tokens
 
 
 cpdef enum TagType:
     POS
-    ENTITY
     SENSE
 
 
 cdef class Tagger:
     cpdef int set_tags(self, Tokens tokens) except -1
-    cpdef class_t predict(self, int i, Tokens tokens) except 0
-    cpdef int tell_answer(self, list gold) except -1
+    cpdef class_t predict(self, int i, Tokens tokens, object golds=*) except 0
  
     cpdef readonly Pool mem
     cpdef readonly Extractor extractor
@@ -26,9 +23,3 @@ cdef class Tagger:
 
     cpdef readonly TagType tag_type
     cpdef readonly list tag_names
-
-    cdef class_t _guess
-    cdef atom_t* _context
-    cdef feat_t* _feats
-    cdef weight_t* _values
-    cdef weight_t* _scores

spacy/tagger.pyx

@@ -1,8 +1,10 @@
 # cython: profile=True
-from __future__ import print_function
 from __future__ import unicode_literals
 from __future__ import division
 
+from .context cimport fill_context
+from .context cimport N_FIELDS
+
 from os import path
 import os
 import shutil
@@ -10,11 +12,7 @@ import random
 import json
 import cython
 
-
-from .context cimport fill_context
-from .context cimport N_FIELDS
-
-from thinc.features cimport ConjFeat
+from thinc.features cimport Feature, count_feats
 
 
 NULL_TAG = 0
@@ -35,7 +33,8 @@ def setup_model_dir(tag_type, tag_names, templates, model_dir):
 
 def train(train_sents, model_dir, nr_iter=10):
     cdef Tokens tokens
-    tagger = Tagger(model_dir)
+    cdef Tagger tagger = Tagger(model_dir)
+    cdef int i
     for _ in range(nr_iter):
         n_corr = 0
         total = 0
@@ -43,9 +42,10 @@ def train(train_sents, model_dir, nr_iter=10):
             assert len(tokens) == len(golds), [t.string for t in tokens]
             for i in range(tokens.length):
                 if tagger.tag_type == POS:
-                    gold = _get_gold_pos(i, golds, tokens.pos)
-                elif tagger.tag_type == ENTITY:
-                    gold = _get_gold_ner(i, golds, tokens.ner)
+                    gold = _get_gold_pos(i, golds)
+                else:
+                    raise StandardError
+
                 guess = tagger.predict(i, tokens)
                 tokens.set_tag(i, tagger.tag_type, guess)
                 if gold is not None:
@@ -59,7 +59,7 @@ def train(train_sents, model_dir, nr_iter=10):
     tagger.model.dump(path.join(model_dir, 'model'))
 
 
-cdef object _get_gold_pos(i, golds, int* pred):
+cdef object _get_gold_pos(i, golds):
     if golds[i] == 0:
         return None
     else:
@@ -96,17 +96,11 @@ cdef class Tagger:
         templates = cfg['templates']
         self.tag_names = cfg['tag_names']
         self.tag_type = cfg['tag_type']
-        self.extractor = Extractor(templates, [ConjFeat] * len(templates))
+        self.extractor = Extractor(templates)
         self.model = LinearModel(len(self.tag_names))
         if path.exists(path.join(model_dir, 'model')):
             self.model.load(path.join(model_dir, 'model'))
 
-        self._context = <atom_t*>self.mem.alloc(N_FIELDS, sizeof(atom_t))
-        self._feats = <feat_t*>self.mem.alloc(self.extractor.n+1, sizeof(feat_t))
-        self._values = <weight_t*>self.mem.alloc(self.extractor.n+1, sizeof(weight_t))
-        self._scores = <weight_t*>self.mem.alloc(self.model.nr_class, sizeof(weight_t))
-        self._guess = NULL_TAG
-
     cpdef int set_tags(self, Tokens tokens) except -1:
         """Assign tags to a Tokens object.
 
@@ -119,7 +113,7 @@ cdef class Tagger:
         for i in range(tokens.length):
             tokens.set_tag(i, self.tag_type, self.predict(i, tokens))
 
-    cpdef class_t predict(self, int i, Tokens tokens) except 0:
+    cpdef class_t predict(self, int i, Tokens tokens, object golds=None) except 0:
         """Predict the tag of tokens[i].  The tagger remembers the features and
         prediction, in case you later call tell_answer.
 
@@ -127,38 +121,20 @@ cdef class Tagger:
         >>> tag = EN.pos_tagger.predict(0, tokens)
         >>> assert tag == EN.pos_tagger.tag_id('DT') == 5
         """
-        fill_context(self._context, i, tokens)
-        self.extractor.extract(self._feats, self._values, self._context, NULL)
-        self._guess = self.model.score(self._scores, self._feats, self._values)
-        return self._guess
-
-    cpdef int tell_answer(self, list golds) except -1:
-        """Provide the correct tag for the word the tagger was last asked to predict.
-        During Tagger.predict, the tagger remembers the features and prediction
-        for the example. These are used to calculate a weight update given the
-        correct label.
-
-        >>> tokens = EN.tokenize('An example sentence.')
-        >>> guess = EN.pos_tagger.predict(1, tokens)
-        >>> JJ = EN.pos_tagger.tag_id('JJ')
-        >>> JJ
-        7
-        >>> EN.pos_tagger.tell_answer(JJ)
-        """
-        cdef class_t guess = self._guess
-        if guess in golds:
-            self.model.update({})
-            return 0
-        best_gold = golds[0]
-        best_score = self._scores[best_gold-1]
-        for gold in golds[1:]:
-            if self._scores[gold-1] > best_gold:
-                best_score = self._scores[best_gold-1]
-                best_gold = gold
-        counts = {guess: {}, best_gold: {}}
-        self.extractor.count(counts[best_gold], self._feats, 1)
-        self.extractor.count(counts[guess], self._feats, -1)
-        self.model.update(counts)
+        cdef int n_feats
+        cdef atom_t[N_FIELDS] context
+        print sizeof(context)
+        fill_context(context, i, tokens.data)
+        cdef Feature* feats = self.extractor.get_feats(context, &n_feats)
+        cdef weight_t* scores = self.model.get_scores(feats, n_feats)
+        cdef class_t guess = _arg_max(scores, self.nr_class)
+        if golds is not None and guess not in golds:
+            best = _arg_max_among(scores, golds)
+            counts = {}
+            count_feats(counts[guess], feats, n_feats, -1)
+            count_feats(counts[best], feats, n_feats, 1)
+            self.model.update(counts)
+        return guess
 
     def tag_id(self, object tag_name):
         """Encode tag_name into a tag ID integer."""
@@ -167,3 +143,25 @@ cdef class Tagger:
             tag_id = len(self.tag_names)
             self.tag_names.append(tag_name)
         return tag_id
+
+
+cdef class_t _arg_max(weight_t* scores, int n_classes):
+    cdef int best = 0
+    cdef weight_t score = scores[best]
+    cdef int i
+    for i in range(1, n_classes):
+        if scores[i] > score:
+            score = scores[i]
+            best = i
+    return best
+
+
+cdef class_t _arg_max_among(weight_t* scores, list classes):
+    cdef int best = classes[0]
+    cdef weight_t score = scores[best]
+    cdef class_t clas
+    for clas in classes:
+        if scores[clas] > score:
+            score = scores[clas]
+            best = clas
+    return best