Update tf pruner example (#3708)

examples/model_compress/pruning/naive_prune_tf.py

@@ -10,9 +10,9 @@ import argparse
 
 import tensorflow as tf
 from tensorflow.keras import Model
-from tensorflow.keras.layers import (Conv2D, Dense, Dropout, Flatten, MaxPool2D)
+from tensorflow.keras.layers import (Conv2D, Dense, Dropout, Flatten, MaxPool2D, BatchNormalization)
 
-from nni.algorithms.compression.tensorflow.pruning import LevelPruner
+from nni.algorithms.compression.tensorflow.pruning import LevelPruner, SlimPruner
 
 class LeNet(Model):
     """
@@ -34,8 +34,10 @@ class LeNet(Model):
         super().__init__()
         self.conv1 = Conv2D(filters=32, kernel_size=conv_size, activation='relu')
         self.pool1 = MaxPool2D(pool_size=2)
+        self.bn1 = BatchNormalization()
         self.conv2 = Conv2D(filters=64, kernel_size=conv_size, activation='relu')
         self.pool2 = MaxPool2D(pool_size=2)
+        self.bn2 = BatchNormalization()
         self.flatten = Flatten()
         self.fc1 = Dense(units=hidden_size, activation='relu')
         self.dropout = Dropout(rate=dropout_rate)
@@ -45,8 +47,10 @@ class LeNet(Model):
         """Override ``Model.call`` to build LeNet-5 model."""
         x = self.conv1(x)
         x = self.pool1(x)
+        x = self.bn1(x)
         x = self.conv2(x)
         x = self.pool2(x)
+        x = self.bn2(x)
         x = self.flatten(x)
         x = self.fc1(x)
         x = self.dropout(x)
@@ -85,12 +89,29 @@ def main(args):
     model = LeNet()
 
     print('start training')
+
     optimizer = tf.keras.optimizers.SGD(learning_rate=0.1, momentum=0.9, decay=1e-4)
+
+    if args.pruner_name == 'slim':
+        def slim_loss(y_true, y_pred):
+            loss_1 = tf.keras.losses.sparse_categorical_crossentropy(y_true=y_true, y_pred=y_pred)
+            weight_list = []
+            for layer in [model.bn1, model.bn2]:
+                weight_list.append([w for w in layer.weights if '/gamma:' in w.name][0].read_value())
+            loss_2 = 0.0001 * tf.reduce_sum([tf.reduce_sum(tf.abs(w)) for w in weight_list])
+            return loss_1 + loss_2
+        model.compile(
+            optimizer=optimizer,
+            loss=slim_loss,
+            metrics=['accuracy']
+        )
+    else:
         model.compile(
             optimizer=optimizer,
             loss='sparse_categorical_crossentropy',
             metrics=['accuracy']
         )
+
     model.fit(
         train_set[0],
         train_set[1],
@@ -103,13 +124,19 @@ def main(args):
     optimizer_finetune = tf.keras.optimizers.SGD(learning_rate=0.001, momentum=0.9, decay=1e-4)
 
     # create_pruner
+    if args.pruner_name == 'level':
         prune_config = [{
             'sparsity': args.sparsity,
             'op_types': ['default'],
         }]
-    
         pruner = LevelPruner(model, prune_config)
-    # pruner = create_pruner(model, args.pruner_name)
+    elif args.pruner_name == 'slim':
+        prune_config = [{
+            'sparsity': args.sparsity,
+            'op_types': ['BatchNormalization'],
+        }]
+        pruner = SlimPruner(model, prune_config)
+
     model = pruner.compress()
 
     model.compile(
@@ -131,7 +158,7 @@ def main(args):
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()
-    parser.add_argument('--pruner_name', type=str, default='level')
+    parser.add_argument('--pruner_name', type=str, default='level', choices=['level', 'slim'])
     parser.add_argument('--batch-size', type=int, default=256)
     parser.add_argument('--pretrain_epochs', type=int, default=10)
     parser.add_argument('--prune_epochs', type=int, default=10)