Correctly reorganized the input for the PLDA

Optimized PCA training

Testing PLDA with no PCA

bob/bio/base/algorithm/PLDA.py

@@ -73,7 +73,7 @@ class PLDA (Algorithm):
 
   def _train_pca(self, training_set):
     """Trains and returns a LinearMachine that is trained using PCA"""
-    data = numpy.vstack([feature for client in training_set for feature in client])
+    data = numpy.vstack([feature for feature in training_set])
 
     logger.info("  -> Training LinearMachine using PCA ")
     trainer = bob.learn.linear.PCATrainer()
@@ -92,20 +92,30 @@ class PLDA (Algorithm):
     machine.resize(machine.shape[0], self.subspace_dimension_pca)
     return machine
 
-  def _perform_pca_client(self, client):
-    """Perform PCA on an array"""
-    return numpy.vstack([self.pca_machine(feature) for feature in client])
-
   def _perform_pca(self, training_set):
     """Perform PCA on data"""
-    return [self._perform_pca_client(client) for client in training_set]
+    return [self.pca_machine(client) for client in training_set]
+
+  def _arrange_data(self, training_files):
+    """Arranges the data to train the PLDA """
+    data = []
+    for client_files in training_files:
+      # at least two files per client are required!
+      if len(client_files) < 2:
+        logger.warn("Skipping one client since the number of client files is only %d", len(client_files))
+        continue
+      data.append(numpy.vstack([feature.flatten() for feature in client_files]))
 
+    # Returns the list of lists of arrays
+    return data
 
   def train_enroller(self, training_features, projector_file):
     """Generates the PLDA base model from a list of arrays (one per identity),
        and a set of training parameters. If PCA is requested, it is trained on the same data.
        Both the trained PLDABase and the PCA machine are written."""
-
+    
+    # arrange PLDA training data
+    training_features = self._arrange_data(training_features)
 
     # train PCA and perform PCA on training data
     if self.subspace_dimension_pca is not None:
@@ -113,6 +123,7 @@ class PLDA (Algorithm):
       training_features = self._perform_pca(training_features)
 
     input_dimension = training_features[0].shape[1]
+
     logger.info("  -> Training PLDA base machine")
 
     # train machine
@@ -146,7 +157,7 @@ class PLDA (Algorithm):
     plda_machine = bob.learn.em.PLDAMachine(self.plda_base)
     # project features, if enabled
     if self.pca_machine is not None:
-      enroll_features = self._perform_pca_client(enroll_features)
+      enroll_features = self._perform_pca(enroll_features)
     # enroll
     self.plda_trainer.enroll(plda_machine, enroll_features)
     return plda_machine

bob/bio/base/test/test_algorithms.py

@@ -358,3 +358,42 @@ def test_plda():
   reference_score = 0.
   assert abs(plda1.score(model, feature) - reference_score) < 1e-5, "The scores differ: %3.8f, %3.8f" % (plda1.score(model, feature), reference_score)
   assert abs(plda1.score_for_multiple_probes(model, [feature, feature]) - reference_score) < 1e-5
+  
+def test_plda_nopca():
+  temp_file = bob.io.base.test_utils.temporary_filename()
+  plda_ref = bob.bio.base.load_resource("plda", "algorithm", preferred_package = 'bob.bio.base')
+  reference_file = pkg_resources.resource_filename('bob.bio.base.test', 'data/plda_nopca_enroller.hdf5')
+  plda_ref.load_enroller(reference_file)
+
+  # generate a smaller PCA subspcae
+  plda = bob.bio.base.algorithm.PLDA(subspace_dimension_of_f = 2, subspace_dimension_of_g = 2, plda_training_iterations = 1, INIT_SEED = seed_value)
+
+  # create random training set
+  train_set = utils.random_training_set_by_id(200, count=20, minimum=0., maximum=255.)
+  # train the projector
+  try:
+    # train projector
+    plda.train_enroller(train_set, temp_file)       
+    assert os.path.exists(temp_file)
+
+    if regenerate_refs: shutil.copy(temp_file, reference_file)
+
+    # check projection matrix
+    assert plda.plda_base.is_similar_to(plda_ref.plda_base)
+
+  finally:
+    if os.path.exists(temp_file): os.remove(temp_file)
+
+  # generate and project random feature
+  feature = utils.random_array(200, 0., 255., seed=84)
+
+  # enroll model from random features
+  reference = pkg_resources.resource_filename('bob.bio.base.test', 'data/plda_nopca_model.hdf5')
+  model = plda.enroll([feature])
+  # execute the preprocessor
+  if regenerate_refs:
+    plda.write_model(model, reference)
+  reference = plda.read_model(reference)
+
+  assert model.is_similar_to(reference)
+