Source code for sinabs.layers.exp_leak

from typing import Optional, Union

import torch

from .lif import LIF
from .reshape import SqueezeMixin

[docs]class ExpLeak(LIF): """Leaky Integrator layer which is a special case of :class:`~sinabs.layers.LIF` without activation function. Neuron dynamics in discrete time: .. math :: V_{mem}(t+1) = \\alpha V_{mem}(t) + (1-\\alpha)\\sum z(t) where :math:`\\alpha = e^{-1/tau_{mem}}` and :math:`\\sum z(t)` represents the sum of all input currents at time :math:`t`. Parameters: tau_mem: Membrane potential time constant. min_v_mem: Lower bound for membrane potential v_mem, clipped at every time step. train_alphas: When True, the discrete decay factor exp(-1/tau) is used for training rather than tau itself. shape: Optionally initialise the layer state with given shape. If None, will be inferred from input_size. norm_input: When True, normalise input current by tau. This helps when training time constants. record_states: When True, will record all internal states such as v_mem or i_syn in a dictionary attribute `recordings`. Default is False. """ def __init__( self, tau_mem: Union[float, torch.Tensor], shape: Optional[torch.Size] = None, train_alphas: bool = False, min_v_mem: Optional[float] = None, norm_input: bool = False, record_states: bool = False, ): super().__init__( tau_mem=tau_mem, tau_syn=None, spike_threshold=None, train_alphas=train_alphas, min_v_mem=min_v_mem, shape=shape, spike_fn=None, reset_fn=None, surrogate_grad_fn=None, norm_input=norm_input, record_states=record_states, ) @property def _param_dict(self) -> dict: param_dict = super()._param_dict param_dict.pop("tau_syn") param_dict.pop("spike_fn") param_dict.pop("reset_fn") param_dict.pop("surrogate_grad_fn") param_dict.pop("spike_threshold") return param_dict
[docs]class ExpLeakSqueeze(ExpLeak, SqueezeMixin): """ExpLeak layer with 4-dimensional input (Batch*Time, Channel, Height, Width). Same as parent ExpLeak class, only takes in squeezed 4D input (Batch*Time, Channel, Height, Width) instead of 5D input (Batch, Time, Channel, Height, Width) in order to be compatible with layers that can only take a 4D input, such as convolutional and pooling layers. Shape: - Input: :math:`(Batch \\times Time, Channel, Height, Width)` or :math:`(Batch \\times Time, Channel)` - Output: Same as input. Attributes: v_mem: The membrane potential resets according to reset_fn for every spike. i_syn: This attribute is only available if tau_syn is not None. """ def __init__(self, batch_size=None, num_timesteps=None, **kwargs): super().__init__(**kwargs) self.squeeze_init(batch_size, num_timesteps)
[docs] def forward(self, input_data: torch.Tensor) -> torch.Tensor: """Forward call wrapper that will flatten the input to and unflatten the output from the super class forward call.""" return self.squeeze_forward(input_data, super().forward)
@property def _param_dict(self) -> dict: return self.squeeze_param_dict(super()._param_dict)