[datashuffler] added the get_batch_epoch function implementing minibatches...

[datashuffler] added the get_batch_epoch function implementing minibatches retrevial ensuring a complete pass over the training set (i.e. an epoch)

bob/learn/tensorflow/datashuffler/Disk.py

@@ -77,6 +77,11 @@ class Disk(Base):
         # TODO: very bad solution to deal with bob.shape images an tf shape images
         self.bob_shape = tuple([input_shape[2]] + list(input_shape[0:2]))
 
+        # number of training examples as a 'list'
+        self.indexes = numpy.array(range(self.data.shape[0]))
+        # shuffle the indexes to get randomized mini-batches
+        numpy.random.shuffle(self.indexes)
+
     def load_from_file(self, file_name):
         d = bob.io.base.load(file_name)
 
@@ -129,3 +134,67 @@ class Disk(Base):
         selected_labels = self.labels[indexes[0:self.batch_size]]
 
         return [selected_data.astype("float32"), selected_labels.astype("int64")]
+
+
+    def get_batch_epoch(self):
+
+      # this is done to rebuild the whole list (i.e. at the end of one epoch)
+      rebuild_indexes = False
+
+      # returned mini-batch
+      selected_data = numpy.zeros(shape=self.shape)
+      selected_labels = [] 
+
+      # if there is not enough available data to fill the current mini-batch
+      # add randomly some examples THAT ARE NOT STILL PRESENT in the dataset !
+      if len(self.indexes) < self.batch_size:
+
+        print "should add examples to the current minibatch {0}".format(len(self.indexes))
+        # since we reached the end of an epoch, we'll hace to reconsider all the data
+        rebuild_indexes = True
+        number_of_examples_to_add = self.batch_size - len(self.indexes) 
+        added_examples = 0
+        
+        # generate a list of potential examples to add to this mini-batch
+        potential_indexes = numpy.array(range(self.data.shape[0]))
+        numpy.random.shuffle(potential_indexes)
+        
+        # add indexes that are not still present in the training data
+        for pot_index in potential_indexes:
+          if pot_index not in self.indexes:
+            self.indexes = numpy.append(self.indexes, [pot_index])
+            added_examples += 1
+            
+            # stop if we have enough examples
+            if added_examples == number_of_examples_to_add:
+              break
+      
+      # populate mini-batch
+      for i in range(self.batch_size):
+
+        current_index = self.batch_size - i - 1
+        
+        # get the data example
+        file_name = self.data[self.indexes[current_index]]
+        data = self.load_from_file(file_name)
+        selected_data[i, ...] = data
+        
+        # normalization
+        selected_data[i, ...] = self.normalize_sample(selected_data[i, ...])
+        
+        # label
+        selected_labels.append(self.labels[self.indexes[current_index]])
+
+        # remove this example from the training set - used once in the epoch
+        new_indexes = numpy.delete(self.indexes, current_index)
+        self.indexes = new_indexes
+
+      if isinstance(selected_labels, list):
+        selected_labels = numpy.array(selected_labels)
+
+      # rebuild whole randomly shuffled training dataset
+      if rebuild_indexes:
+        self.indexes = numpy.array(range(self.data.shape[0]))
+        numpy.random.shuffle(self.indexes)
+
+      return [selected_data.astype("float32"), selected_labels.astype("int64")]