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244 lines
9.3 KiB
244 lines
9.3 KiB
import math
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import warnings
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from torch import Tensor
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import torch.nn as nn
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def zeros_():
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"""Return the initializer filling the input Tensor with the scalar zeros"""
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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return nn.init.zeros_(tensor)
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return initializer
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def ones_():
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"""Return the initializer filling the input Tensor with the scalar ones"""
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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return nn.init.ones_(tensor)
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return initializer
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def uniform_(a: float = 0., b: float = 1.):
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r"""Return the initializer filling the input Tensor with values drawn from the uniform
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distribution :math:`\mathcal{U}(a, b)`.
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Args:
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a (float): the lower bound of the uniform distribution. Defaults 0.0.
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b (float): the upper bound of the uniform distribution. Defaults 1.0.
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"""
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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return nn.init.uniform_(tensor, a, b)
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return initializer
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def normal_(mean: float = 0., std: float = 1.):
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r"""Return the initializer filling the input Tensor with values drawn from the normal distribution
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.. math::
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\mathcal{N}(\text{mean}, \text{std}^2)
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Args:
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mean (float): the mean of the normal distribution. Defaults 0.0.
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std (float): the standard deviation of the normal distribution. Defaults 1.0.
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"""
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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return nn.init.normal_(tensor, mean, std)
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return initializer
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def trunc_normal_(mean: float = 0., std: float = 1., a: float = -2., b: float = 2.):
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r"""Return the initializer filling the input Tensor with values drawn from a truncated
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normal distribution. The values are effectively drawn from the
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normal distribution :math:`\mathcal{N}(\text{mean}, \text{std}^2)`
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with values outside :math:`[a, b]` redrawn until they are within
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the bounds. The method used for generating the random values works
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best when :math:`a \leq \text{mean} \leq b`.
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Args:
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mean (float): the mean of the normal distribution. Defaults 0.0.
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std (float): the standard deviation of the normal distribution. Defaults 1.0.
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a (float): the minimum cutoff value. Defaults -2.0.
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b (float): the maximum cutoff value. Defaults 2.0.
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"""
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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return nn.init.trunc_normal_(tensor, mean, std, a, b)
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return initializer
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def kaiming_uniform_(a=0, mode='fan_in', nonlinearity='leaky_relu'):
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r"""Return the initializer filling the input `Tensor` with values according to the method
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described in `Delving deep into rectifiers: Surpassing human-level
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performance on ImageNet classification` - He, K. et al. (2015), using a
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uniform distribution. The resulting tensor will have values sampled from
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:math:`\mathcal{U}(-\text{bound}, \text{bound})` where
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.. math::
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\text{bound} = \text{gain} \times \sqrt{\frac{3}{\text{fan_mode}}}
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Also known as 'He initialization'.
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Args:
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a (int): the negative slope of the rectifier used after this layer (only used with ``'leaky_relu'``).
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mode (str, optional): either ``'fan_in'`` (default) or ``'fan_out'``. Choosing ``'fan_in'``
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preserves the magnitude of the variance of the weights in the
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forward pass. Choosing ``'fan_out'`` preserves the magnitudes in the
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backwards pass.
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nonlinearity (str, optional): the non-linear function (`nn.functional` name),
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recommended to use only with ``'relu'`` or ``'leaky_relu'`` (default).
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"""
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# adapted from torch.nn.init
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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if 0 in tensor.shape:
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warnings.warn("Initializing zero-element tensors is a no-op")
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return tensor
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if mode == 'fan_in':
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assert fan_in is not None, 'Fan_in is not provided.'
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fan = fan_in
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elif mode == 'fan_out':
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assert fan_out is not None, 'Fan_out is not provided.'
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fan = fan_out
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else:
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raise ValueError(f'Invalid initialization mode \'{mode}\'')
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std = nn.init.calculate_gain(nonlinearity, a) / math.sqrt(fan)
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bound = math.sqrt(3.) * std
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return nn.init.uniform_(tensor, -bound, bound)
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return initializer
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def kaiming_normal_(a=0, mode='fan_in', nonlinearity='leaky_relu'):
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r"""Return the initializer filling the input `Tensor` with values according to the method
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described in `Delving deep into rectifiers: Surpassing human-level
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performance on ImageNet classification` - He, K. et al. (2015), using a
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normal distribution. The resulting tensor will have values sampled from
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:math:`\mathcal{N}(0, \text{std}^2)` where
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.. math::
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\text{std} = \frac{\text{gain}}{\sqrt{\text{fan_mode}}}
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Also known as 'He initialization'.
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Args:
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a (int): the negative slope of the rectifier used after this layer (only used with ``'leaky_relu'``).
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mode (str, optional): either ``'fan_in'`` (default) or ``'fan_out'``. Choosing ``'fan_in'``
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preserves the magnitude of the variance of the weights in the
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forward pass. Choosing ``'fan_out'`` preserves the magnitudes in the
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backwards pass.
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nonlinearity (str, optional): the non-linear function (`nn.functional` name),
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recommended to use only with ``'relu'`` or ``'leaky_relu'`` (default).
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"""
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# adapted from torch.nn.init
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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if 0 in tensor.shape:
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warnings.warn("Initializing zero-element tensors is a no-op")
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return tensor
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if mode == 'fan_in':
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assert fan_in is not None, 'Fan_in is not provided.'
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fan = fan_in
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elif mode == 'fan_out':
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assert fan_out is not None, 'Fan_out is not provided.'
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fan = fan_out
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else:
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raise ValueError(f'Invalid initialization mode \'{mode}\'')
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std = nn.init.calculate_gain(nonlinearity, a) / math.sqrt(fan)
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return nn.init.normal_(tensor, 0, std)
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return initializer
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def xavier_uniform_(a: float = math.sqrt(3.), scale: float = 2., gain: float = 1.):
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r"""Return the initializer filling the input `Tensor` with values according to the method
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described in `Understanding the difficulty of training deep feedforward
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neural networks` - Glorot, X. & Bengio, Y. (2010), using a uniform
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distribution. The resulting tensor will have values sampled from
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:math:`\mathcal{U}(-a, a)` where
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.. math::
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a = \text{gain} \times \sqrt{\frac{6}{\text{fan_in} + \text{fan_out}}}
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Also known as 'Glorot initialization'.
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Args:
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a (float, optional): an optional scaling factor used to calculate uniform
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bounds from standard deviation. Defaults ``math.sqrt(3.)``.
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scale (float, optional): an optional scaling factor used to calculate standard deviation. Defaults 2.0.
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gain (float, optional): an optional scaling factor. Defaults 1.0.
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"""
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# adapted from torch.nn.init
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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assert fan_in is not None, 'Fan_in is not provided.'
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fan = fan_in
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if fan_out is not None:
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fan += fan_out
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std = gain * math.sqrt(scale / float(fan))
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bound = a * std
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return nn.init.uniform_(tensor, -bound, bound)
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return initializer
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def xavier_normal_(scale: float = 2., gain: float = 1.):
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r"""Return the initializer filling the input `Tensor` with values according to the method
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described in `Understanding the difficulty of training deep feedforward
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neural networks` - Glorot, X. & Bengio, Y. (2010), using a normal
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distribution. The resulting tensor will have values sampled from
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:math:`\mathcal{N}(0, \text{std}^2)` where
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.. math::
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\text{std} = \text{gain} \times \sqrt{\frac{2}{\text{fan_in} + \text{fan_out}}}
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Also known as 'Glorot initialization'.
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Args:
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scale (float, optional): an optional scaling factor used to calculate standard deviation. Defaults 2.0.
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gain (float, optional): an optional scaling factor. Defaults 1.0.
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"""
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# adapted from torch.nn.init
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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assert fan_in is not None, 'Fan_in is not provided.'
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fan = fan_in
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if fan_out is not None:
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fan += fan_out
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std = gain * math.sqrt(scale / float(fan))
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return nn.init.normal_(tensor, 0., std)
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return initializer
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def lecun_uniform_():
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# adapted from jax.nn.initializers
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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assert fan_in is not None, 'Fan_in is not provided.'
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var = 1.0 / fan_in
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bound = math.sqrt(3 * var)
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return nn.init.uniform_(tensor, -bound, bound)
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return initializer
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def lecun_normal_():
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# adapted from jax.nn.initializers
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def initializer(tensor: Tensor, fan_in: int = None, fan_out: int = None):
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assert fan_in is not None, 'Fan_in is not provided.'
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std = math.sqrt(1.0 / fan_in)
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return nn.init.trunc_normal_(tensor, std=std / .87962566103423978)
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return initializer |