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early_stopping = tf.keras.callbacks.EarlyStopping( |
patience=10, restore_best_weights=True |
) |
# Initialize SWA from tf-hub. |
SWA = tfa.optimizers.SWA |
# Compile and train the teacher model. |
teacher_model = get_training_model() |
teacher_model.load_weights(\"initial_teacher_model.h5\") |
teacher_model.compile( |
# Notice that we are wrapping our optimizer within SWA |
optimizer=SWA(tf.keras.optimizers.Adam()), |
loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True), |
metrics=[\"accuracy\"], |
) |
history = teacher_model.fit( |
train_clean_ds, |
epochs=EPOCHS, |
validation_data=validation_ds, |
callbacks=[reduce_lr, early_stopping], |
) |
# Evaluate the teacher model on the test set. |
_, acc = teacher_model.evaluate(test_ds, verbose=0) |
print(f\"Test accuracy: {acc*100}%\") |
Epoch 1/5 |
387/387 [==============================] - 73s 78ms/step - loss: 1.7785 - accuracy: 0.3582 - val_loss: 2.0589 - val_accuracy: 0.3920 |
Epoch 2/5 |
387/387 [==============================] - 28s 71ms/step - loss: 1.2493 - accuracy: 0.5542 - val_loss: 1.4228 - val_accuracy: 0.5380 |
Epoch 3/5 |
387/387 [==============================] - 28s 73ms/step - loss: 1.0294 - accuracy: 0.6350 - val_loss: 1.4422 - val_accuracy: 0.5900 |
Epoch 4/5 |
387/387 [==============================] - 28s 73ms/step - loss: 0.8954 - accuracy: 0.6864 - val_loss: 1.2189 - val_accuracy: 0.6520 |
Epoch 5/5 |
387/387 [==============================] - 28s 73ms/step - loss: 0.7879 - accuracy: 0.7231 - val_loss: 0.9790 - val_accuracy: 0.6500 |
Test accuracy: 65.83999991416931% |
Define a self-training utility |
For this part, we will borrow the Distiller class from this Keras Example. |
# Majority of the code is taken from: |
# https://keras.io/examples/vision/knowledge_distillation/ |
class SelfTrainer(tf.keras.Model): |
def __init__(self, student, teacher): |
super(SelfTrainer, self).__init__() |
self.student = student |
self.teacher = teacher |
def compile( |
self, optimizer, metrics, student_loss_fn, distillation_loss_fn, temperature=3, |
): |
super(SelfTrainer, self).compile(optimizer=optimizer, metrics=metrics) |
self.student_loss_fn = student_loss_fn |
self.distillation_loss_fn = distillation_loss_fn |
self.temperature = temperature |
def train_step(self, data): |
# Since our dataset is a zip of two independent datasets, |
# after initially parsing them, we segregate the |
# respective images and labels next. |
clean_ds, noisy_ds = data |
clean_images, _ = clean_ds |
noisy_images, y = noisy_ds |
# Forward pass of teacher |
teacher_predictions = self.teacher(clean_images, training=False) |
with tf.GradientTape() as tape: |
# Forward pass of student |
student_predictions = self.student(noisy_images, training=True) |
# Compute losses |
student_loss = self.student_loss_fn(y, student_predictions) |
distillation_loss = self.distillation_loss_fn( |
tf.nn.softmax(teacher_predictions / self.temperature, axis=1), |
tf.nn.softmax(student_predictions / self.temperature, axis=1), |
) |
total_loss = (student_loss + distillation_loss) / 2 |
# Compute gradients |
trainable_vars = self.student.trainable_variables |
gradients = tape.gradient(total_loss, trainable_vars) |
# Update weights |
self.optimizer.apply_gradients(zip(gradients, trainable_vars)) |
# Update the metrics configured in `compile()` |
self.compiled_metrics.update_state( |
y, tf.nn.softmax(student_predictions, axis=1) |
) |
# Return a dict of performance |
results = {m.name: m.result() for m in self.metrics} |
results.update({\"total_loss\": total_loss}) |
return results |
def test_step(self, data): |
# During inference, we only pass a dataset consisting images and labels. |
x, y = data |
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