Merge pull request #101 from xinghai-sun/ds2_improve

Add shuffle type of instance_shuffle and batch_shuffle_clipped.

Author: xinghai-sun

deep_speech_2/compute_mean_std.py

@@ -80,7 +80,7 @@ def batch_reader_creator(self,
                              padding_to=-1,
                              flatten=False,
                              sortagrad=False,
-                             batch_shuffle=False):
+                             shuffle_method="batch_shuffle"):
         """
         Batch data reader creator for audio data. Return a callable generator
         function to produce batches of data.
@@ -104,12 +104,22 @@ def batch_reader_creator(self,
         :param sortagrad: If set True, sort the instances by audio duration
                           in the first epoch for speed up training.
         :type sortagrad: bool
-        :param batch_shuffle: If set True, instances are batch-wise shuffled.
-                              For more details, please see 
-                              ``_batch_shuffle.__doc__``.
-                              If sortagrad is True, batch_shuffle is disabled
+        :param shuffle_method: Shuffle method. Options:
+                                '' or None: no shuffle.
+                                'instance_shuffle': instance-wise shuffle.
+                                'batch_shuffle': similarly-sized instances are
+                                                 put into batches, and then
+                                                 batch-wise shuffle the batches.
+                                                 For more details, please see
+                                                 ``_batch_shuffle.__doc__``.
+                                'batch_shuffle_clipped': 'batch_shuffle' with
+                                                         head shift and tail
+                                                         clipping. For more
+                                                         details, please see
+                                                         ``_batch_shuffle``.
+                              If sortagrad is True, shuffle is disabled
                               for the first epoch.
-        :type batch_shuffle: bool
+        :type shuffle_method: None|str
         :return: Batch reader function, producing batches of data when called.
         :rtype: callable
         """
@@ -123,8 +133,20 @@ def batch_reader():
             # sort (by duration) or batch-wise shuffle the manifest
             if self._epoch == 0 and sortagrad:
                 manifest.sort(key=lambda x: x["duration"])
-            elif batch_shuffle:
-                manifest = self._batch_shuffle(manifest, batch_size)
+            else:
+                if shuffle_method == "batch_shuffle":
+                    manifest = self._batch_shuffle(
+                        manifest, batch_size, clipped=False)
+                elif shuffle_method == "batch_shuffle_clipped":
+                    manifest = self._batch_shuffle(
+                        manifest, batch_size, clipped=True)
+                elif shuffle_method == "instance_shuffle":
+                    self._rng.shuffle(manifest)
+                elif not shuffle_method:
+                    pass
+                else:
+                    raise ValueError("Unknown shuffle method %s." %
+                                     shuffle_method)
             # prepare batches
             instance_reader = self._instance_reader_creator(manifest)
             batch = []
@@ -218,7 +240,7 @@ def _padding_batch(self, batch, padding_to=-1, flatten=False):
             new_batch.append((padded_audio, text))
         return new_batch
 
-    def _batch_shuffle(self, manifest, batch_size):
+    def _batch_shuffle(self, manifest, batch_size, clipped=False):
         """Put similarly-sized instances into minibatches for better efficiency
         and make a batch-wise shuffle.
 
@@ -233,6 +255,9 @@ def _batch_shuffle(self, manifest, batch_size):
         :param batch_size: Batch size. This size is also used for generate
                            a random number for batch shuffle.
         :type batch_size: int
+        :param clipped: Whether to clip the heading (small shift) and trailing
+                        (incomplete batch) instances.
+        :type clipped: bool
         :return: Batch shuffled mainifest.
         :rtype: list
         """
@@ -241,7 +266,8 @@ def _batch_shuffle(self, manifest, batch_size):
         batch_manifest = zip(*[iter(manifest[shift_len:])] * batch_size)
         self._rng.shuffle(batch_manifest)
         batch_manifest = list(sum(batch_manifest, ()))
-        res_len = len(manifest) - shift_len - len(batch_manifest)
-        batch_manifest.extend(manifest[-res_len:])
-        batch_manifest.extend(manifest[0:shift_len])
+        if not clipped:
+            res_len = len(manifest) - shift_len - len(batch_manifest)
+            batch_manifest.extend(manifest[-res_len:])
+            batch_manifest.extend(manifest[0:shift_len])
         return batch_manifest