Add EfficientNetB0 to B7 to Keras Applications.

Also add swish activation to keras.activations (used by EfficientNets).

PiperOrigin-RevId: 286614744
Change-Id: Ieba8b1f47735bdbb31c4efc84f45f763b9daa9a4

tensorflow/python/keras/activations.py

@@ -182,6 +182,19 @@ def softsign(x):
   return nn.softsign(x)
 
 
+@keras_export('keras.activations.swish')
+def swish(x):
+  """Swish activation function.
+
+  Arguments:
+      x: Input tensor.
+
+  Returns:
+      The swish activation applied to `x`.
+  """
+  return nn.swish(x)
+
+
 @keras_export('keras.activations.relu')
 def relu(x, alpha=0., max_value=None, threshold=0):
   """Applies the rectified linear unit activation function.

tensorflow/python/keras/applications/BUILD

@@ -15,6 +15,7 @@ py_library(
     srcs = [
         "__init__.py",
         "densenet.py",
+        "efficientnet.py",
         "imagenet_utils.py",
         "inception_resnet_v2.py",
         "inception_v3.py",

tensorflow/python/keras/applications/applications_test.py

@@ -22,6 +22,7 @@
 
 from tensorflow.python.keras import backend
 from tensorflow.python.keras.applications import densenet
+from tensorflow.python.keras.applications import efficientnet
 from tensorflow.python.keras.applications import inception_resnet_v2
 from tensorflow.python.keras.applications import inception_v3
 from tensorflow.python.keras.applications import mobilenet
@@ -52,6 +53,14 @@
     (densenet.DenseNet121, 1024),
     (densenet.DenseNet169, 1664),
     (densenet.DenseNet201, 1920),
+    (efficientnet.EfficientNetB0, 1280),
+    (efficientnet.EfficientNetB1, 1280),
+    (efficientnet.EfficientNetB2, 1408),
+    (efficientnet.EfficientNetB3, 1536),
+    (efficientnet.EfficientNetB4, 1792),
+    (efficientnet.EfficientNetB5, 2048),
+    (efficientnet.EfficientNetB6, 2304),
+    (efficientnet.EfficientNetB7, 2560),
 ]
 
 NASNET_LIST = [
@@ -72,6 +81,16 @@ def assertShapeEqual(self, shape1, shape2):
       if v1 != v2:
         raise AssertionError('Shapes differ: %s vs %s' % (shape1, shape2))
 
+  @parameterized.parameters(*MODEL_LIST)
+  def test_application_base(self, app, _):
+    # Can be instantiated with default arguments
+    model = app(weights=None)
+    # Can be serialized and deserialized
+    config = model.get_config()
+    reconstructed_model = model.__class__.from_config(config)
+    self.assertEqual(len(model.weights), len(reconstructed_model.weights))
+    backend.clear_session()
+
   @parameterized.parameters(*MODEL_LIST)
   def test_application_notop(self, app, last_dim):
     if 'NASNet' in app.__name__: