def __init__(self,
num_features: int,
axis: int = -1,
event_ndims: int = 1):
"""
Construct a new :class:`FeatureShufflingFlow`.
Args:
num_features: The size of the feature axis.
axis: The feature axis, to apply the transformation.
event_ndims: Number of dimensions to be considered as the
event dimensions. `x.ndims - event_ndims == log_det.ndims`.
"""
super().__init__(axis=int(axis),
event_ndims=event_ndims,
explicitly_invertible=True)
self.num_features = num_features
# initialize the permutation variable, and the inverse permutation
permutation = torch.randperm(num_features, dtype=torch.int64)
inv_permutation = torch.argsort(permutation)
# register the permutation as layer parameter, such that it could be
# persisted by Model checkpoint.
add_parameter(self, 'permutation', permutation, requires_grad=False)
add_parameter(self,
'inv_permutation',
inv_permutation,
requires_grad=False)
def __init__(self,
shape: List[int],
initializer: TensorInitArgType,
device: Optional[str] = None):
super().__init__(shape)
device = device or current_device()
add_parameter(self, 'value',
variable(shape, initializer=initializer, device=device))
def __init__(self,
shape: List[int],
initializer: TensorInitArgType,
norm_axis: int = 1,
device: Optional[str] = None,
epsilon: float = EPSILON):
super().__init__(shape)
self.norm_axis = norm_axis
device = device or current_device()
self.epsilon = epsilon
weight = variable(shape, initializer=initializer, device=device)
with torch.no_grad():
v, _ = weight_norm_decompose(weight, norm_axis, epsilon)
add_parameter(self, 'v', v)
def __init__(self, seed_matrix, dtype=torch.float32, epsilon=1e-5):
initial_matrix = la.qr(seed_matrix)[0]
super().__init__(initial_matrix.shape[0])
matrix_shape = list(initial_matrix.shape)
# self.size = matrix_shape[0]
initial_P, initial_L, initial_U = la.lu(initial_matrix)
initial_s = np.diag(initial_U)
initial_sign = np.sign(initial_s)
initial_log_s = np.log(np.maximum(np.abs(initial_s), epsilon))
initial_U = np.triu(initial_U, k=1) # 上三角阵，对角线元素为0
add_buffer(self, 'P', as_tensor(initial_P,
dtype=dtype,
force_copy=True))
add_parameter(self, 'pre_L',
as_tensor(initial_L, dtype=dtype, force_copy=True))
add_buffer(
self, 'L_mask',
as_tensor(np.tril(np.ones(matrix_shape), k=-1),
dtype=dtype,
force_copy=True))
add_parameter(self, 'pre_U',
as_tensor(initial_U, dtype=dtype, force_copy=True))
add_buffer(
self, 'U_mask',
as_tensor(np.triu(np.ones(matrix_shape), k=1),
dtype=dtype,
force_copy=True))
add_buffer(self, 'sign',
as_tensor(initial_sign, dtype=dtype, force_copy=True))
add_parameter(self, 'log_s',
as_tensor(initial_log_s, dtype=dtype, force_copy=True))
def __init__(
self,
num_features,
event_ndims: int = 1,
axis: int = -1,
w_init: TensorInitArgType = init.normal,
b_init: TensorInitArgType = init.zeros,
u_init: TensorInitArgType = init.normal,
):
super().__init__(axis=axis,
event_ndims=event_ndims,
explicitly_invertible=False)
add_parameter(
self,
'w',
value=variable([1, num_features], initializer=w_init),
)
add_parameter(self, 'b', value=variable([1], initializer=b_init))
add_parameter(self,
'u',
value=variable([1, num_features], initializer=u_init))
self.num_features = num_features
self.u_hat = None
def __init__(self, seed_matrix, dtype=torch.float32):
initial_matrix = la.qr(seed_matrix)[0] # 获取正交矩阵
super().__init__(initial_matrix.shape[0])
add_parameter(self, 'matrix',
as_tensor(seed_matrix, dtype=dtype, force_copy=True))
def __init__(self,
num_features: int,
axis: int = -1,
event_ndims: int = 1,
scale: Union[str, ActNormScaleType] = 'exp',
initialized: bool = False,
epsilon: float = 1e-5,
dtype: str = 'float32'):
"""
Construct a new :class:`ActNorm` instance.
Args:
num_features: The size of the feature axis.
scale: One of {"exp", "linear"}.
If "exp", ``y = (x + bias) * tf.exp(log_scale)``.
If "linear", ``y = (x + bias) * scale``.
Defaults to "exp".
axis: The axis to apply ActNorm.
Dimensions not in `axis` will be averaged out when computing
the mean of activations. Default `-1`, the last dimension.
All items of the `axis` should be covered by `event_ndims`.
event_ndims: Number of value dimensions in both `x` and `y`.
`x.ndims - event_ndims == log_det.ndims` and
`y.ndims - event_ndims == log_det.ndims`.
initialized: Whether or not the variables have been
initialized? Defaults to :obj:`False`, where the first input
`x` in the forward pass will be used to initialize the variables.
epsilon: The infinitesimal constant to avoid dividing by zero or
taking logarithm of zero.
dtype: Dtype of the parameters.
"""
# validate the arguments
scale_type = ActNormScaleType(scale)
epsilon = float(epsilon)
if scale_type == ActNormScaleType.EXP:
scale = ExpScale()
pre_scale_init = partial(init.fill, fill_value=0.)
elif scale_type == ActNormScaleType.LINEAR:
scale = LinearScale(epsilon=epsilon)
pre_scale_init = partial(init.fill, fill_value=1.)
else: # pragma: no cover
raise ValueError(f'Unsupported `scale_type`: {scale_type}')
# construct the layer
super().__init__(axis=axis,
event_ndims=event_ndims,
explicitly_invertible=True)
self.num_features = num_features
self.scale = scale
self.scale_type = scale_type.value
self.epsilon = epsilon
self.initialized = initialized
add_parameter(
self,
'pre_scale',
variable([num_features], dtype=dtype, initializer=pre_scale_init),
)
add_parameter(
self,
'bias',
variable([num_features], dtype=dtype, initializer=init.zeros),
)