|
|
from keras.src.api_export import keras_export |
|
|
|
|
|
|
|
|
@keras_export(["keras.Initializer", "keras.initializers.Initializer"]) |
|
|
class Initializer: |
|
|
"""Initializer base class: all Keras initializers inherit from this class. |
|
|
|
|
|
Initializers should implement a `__call__()` method with the following |
|
|
signature: |
|
|
|
|
|
```python |
|
|
def __call__(self, shape, dtype=None, **kwargs): |
|
|
# returns a tensor of shape `shape` and dtype `dtype` |
|
|
# containing values drawn from a distribution of your choice. |
|
|
``` |
|
|
|
|
|
Optionally, you can also implement the method `get_config()` and the class |
|
|
method `from_config` in order to support serialization, just like with |
|
|
any Keras object. |
|
|
|
|
|
Here's a simple example: a random normal initializer. |
|
|
|
|
|
```python |
|
|
class ExampleRandomNormal(Initializer): |
|
|
def __init__(self, mean, stddev): |
|
|
self.mean = mean |
|
|
self.stddev = stddev |
|
|
|
|
|
def __call__(self, shape, dtype=None, **kwargs): |
|
|
return keras.random.normal( |
|
|
shape, mean=self.mean, stddev=self.stddev, dtype=dtype |
|
|
) |
|
|
|
|
|
def get_config(self): # To support serialization |
|
|
return {"mean": self.mean, "stddev": self.stddev} |
|
|
``` |
|
|
|
|
|
Note that we don't have to implement `from_config()` in the example above |
|
|
since the constructor arguments of the class the keys in the config returned |
|
|
by `get_config()` are the same. In this case, the default `from_config()` |
|
|
works fine. |
|
|
""" |
|
|
|
|
|
def __call__(self, shape, dtype=None): |
|
|
"""Returns a tensor object initialized as specified by the initializer. |
|
|
|
|
|
Args: |
|
|
shape: Shape of the tensor. |
|
|
dtype: Optional dtype of the tensor. |
|
|
""" |
|
|
raise NotImplementedError( |
|
|
"Initializer subclasses must implement the `__call__()` method." |
|
|
) |
|
|
|
|
|
def get_config(self): |
|
|
"""Returns the initializer's configuration as a JSON-serializable dict. |
|
|
|
|
|
Returns: |
|
|
A JSON-serializable Python dict. |
|
|
""" |
|
|
return {} |
|
|
|
|
|
@classmethod |
|
|
def from_config(cls, config): |
|
|
"""Instantiates an initializer from a configuration dictionary. |
|
|
|
|
|
Example: |
|
|
|
|
|
```python |
|
|
initializer = RandomUniform(-1, 1) |
|
|
config = initializer.get_config() |
|
|
initializer = RandomUniform.from_config(config) |
|
|
``` |
|
|
|
|
|
Args: |
|
|
config: A Python dictionary, the output of `get_config()`. |
|
|
|
|
|
Returns: |
|
|
An `Initializer` instance. |
|
|
""" |
|
|
return cls(**config) |
|
|
|
|
|
def clone(self): |
|
|
return self.__class__.from_config(self.get_config()) |
|
|
|
