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def from_config(cls, config): |
return cls(**config) |
model = CustomModel([16, 16, 10]) |
# Build the model by calling it |
input_arr = tf.random.uniform((1, 5)) |
outputs = model(input_arr) |
model.save("my_model") |
# Option 1: Load with the custom_object argument. |
loaded_1 = keras.models.load_model( |
"my_model", custom_objects={"CustomModel": CustomModel} |
) |
# Option 2: Load without the CustomModel class. |
# Delete the custom-defined model class to ensure that the loader does not have |
# access to it. |
del CustomModel |
loaded_2 = keras.models.load_model("my_model") |
np.testing.assert_allclose(loaded_1(input_arr), outputs) |
np.testing.assert_allclose(loaded_2(input_arr), outputs) |
print("Original model:", model) |
print("Model Loaded with custom objects:", loaded_1) |
print("Model loaded without the custom object class:", loaded_2) |
INFO:tensorflow:Assets written to: my_model/assets |
WARNING:tensorflow:No training configuration found in save file, so the model was *not* compiled. Compile it manually. |
WARNING:tensorflow:No training configuration found in save file, so the model was *not* compiled. Compile it manually. |
Original model: <__main__.CustomModel object at 0x151ad0990> |
Model Loaded with custom objects: <__main__.CustomModel object at 0x151b03850> |
Model loaded without the custom object class: <tensorflow.python.keras.saving.saved_model.load.CustomModel object at 0x151bb0310> |
The first loaded model is loaded using the config and CustomModel class. The second model is loaded by dynamically creating the model class that acts like the original model. |
Configuring the SavedModel |
New in TensoFlow 2.4 The argument save_traces has been added to model.save, which allows you to toggle SavedModel function tracing. Functions are saved to allow the Keras to re-load custom objects without the original class definitons, so when save_traces=False, all custom objects must have defined get_config/from_config methods. When loading, the custom objects must be passed to the custom_objects argument. save_traces=False reduces the disk space used by the SavedModel and saving time. |
Keras H5 format |
Keras also supports saving a single HDF5 file containing the model's architecture, weights values, and compile() information. It is a light-weight alternative to SavedModel. |
Example: |
model = get_model() |
# Train the model. |
test_input = np.random.random((128, 32)) |
test_target = np.random.random((128, 1)) |
model.fit(test_input, test_target) |
# Calling `save('my_model.h5')` creates a h5 file `my_model.h5`. |
model.save("my_h5_model.h5") |
# It can be used to reconstruct the model identically. |
reconstructed_model = keras.models.load_model("my_h5_model.h5") |
# Let's check: |
np.testing.assert_allclose( |
model.predict(test_input), reconstructed_model.predict(test_input) |
) |
# The reconstructed model is already compiled and has retained the optimizer |
# state, so training can resume: |
reconstructed_model.fit(test_input, test_target) |
4/4 [==============================] - 0s 967us/step - loss: 0.8106 |
4/4 [==============================] - 0s 1ms/step - loss: 0.7184 |
<tensorflow.python.keras.callbacks.History at 0x151d5ac90> |
Limitations |
Compared to the SavedModel format, there are two things that don't get included in the H5 file: |
External losses & metrics added via model.add_loss() & model.add_metric() are not saved (unlike SavedModel). If you have such losses & metrics on your model and you want to resume training, you need to add these losses back yourself after loading the model. Note that this does not apply to losses/metrics created inside layers via self.add_loss() & self.add_metric(). As long as the layer gets loaded, these losses & metrics are kept, since they are part of the call method of the layer. |
The computation graph of custom objects such as custom layers is not included in the saved file. At loading time, Keras will need access to the Python classes/functions of these objects in order to reconstruct the model. See Custom objects. |
Saving the architecture |
The model's configuration (or architecture) specifies what layers the model contains, and how these layers are connected*. If you have the configuration of a model, then the model can be created with a freshly initialized state for the weights and no compilation information. |
*Note this only applies to models defined using the functional or Sequential apis not subclassed models. |
Configuration of a Sequential model or Functional API model |
These types of models are explicit graphs of layers: their configuration is always available in a structured form. |
APIs |
get_config() and from_config() |
tf.keras.models.model_to_json() and tf.keras.models.model_from_json() |
get_config() and from_config() |
Calling config = model.get_config() will return a Python dict containing the configuration of the model. The same model can then be reconstructed via Sequential.from_config(config) (for a Sequential model) or Model.from_config(config) (for a Functional API model). |
The same workflow also works for any serializable layer. |
Layer example: |
layer = keras.layers.Dense(3, activation="relu") |
layer_config = layer.get_config() |
new_layer = keras.layers.Dense.from_config(layer_config) |
Sequential model example: |
model = keras.Sequential([keras.Input((32,)), keras.layers.Dense(1)]) |
config = model.get_config() |
new_model = keras.Sequential.from_config(config) |
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