add noise_shape in Dropout layer. (fix #244)

tensorpack/models/regularize.py

@@ -53,7 +53,7 @@ def regularize_cost(regex, func, name='regularize_cost'):
 
 
 @layer_register(log_shape=False, use_scope=False)
-def Dropout(x, keep_prob=0.5, is_training=None):
+def Dropout(x, keep_prob=0.5, is_training=None, noise_shape=None):
     """
     Dropout layer as in the paper `Dropout: a Simple Way to Prevent
     Neural Networks from Overfitting <http://dl.acm.org/citation.cfm?id=2670313>`_.
@@ -63,8 +63,9 @@ def Dropout(x, keep_prob=0.5, is_training=None):
             when is_training=True.
         is_training (bool): If None, will use the current :class:`tensorpack.tfutils.TowerContext`
             to figure out.
+        noise_shape: same as `tf.nn.dropout`.
     """
     if is_training is None:
         is_training = get_current_tower_context().is_training
     keep_prob = tf.constant(keep_prob if is_training else 1.0)
-    return tf.nn.dropout(x, keep_prob)
+    return tf.nn.dropout(x, keep_prob, noise_shape=noise_shape)