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375 lines
14 KiB
375 lines
14 KiB
5 months ago
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import torch
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from torch import Tensor
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from .optimizer import (Optimizer, _default_to_fused_or_foreach, _use_grad_for_differentiable,
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_differentiable_doc, _foreach_doc, _maximize_doc, _view_as_real)
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from typing import List, Optional
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__all__ = ["RMSprop", "rmsprop"]
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class RMSprop(Optimizer):
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def __init__(
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self,
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params,
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lr=1e-2,
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alpha=0.99,
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eps=1e-8,
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weight_decay=0,
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momentum=0,
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centered=False,
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foreach: Optional[bool] = None,
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maximize: bool = False,
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differentiable: bool = False,
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):
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if not 0.0 <= lr:
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raise ValueError(f"Invalid learning rate: {lr}")
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if not 0.0 <= eps:
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raise ValueError(f"Invalid epsilon value: {eps}")
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if not 0.0 <= momentum:
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raise ValueError(f"Invalid momentum value: {momentum}")
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if not 0.0 <= weight_decay:
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raise ValueError(f"Invalid weight_decay value: {weight_decay}")
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if not 0.0 <= alpha:
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raise ValueError(f"Invalid alpha value: {alpha}")
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defaults = dict(
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lr=lr,
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momentum=momentum,
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alpha=alpha,
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eps=eps,
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centered=centered,
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weight_decay=weight_decay,
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foreach=foreach,
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maximize=maximize,
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differentiable=differentiable,
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)
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super().__init__(params, defaults)
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def __setstate__(self, state):
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super().__setstate__(state)
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for group in self.param_groups:
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group.setdefault("momentum", 0)
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group.setdefault("centered", False)
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group.setdefault("foreach", None)
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group.setdefault("maximize", False)
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group.setdefault("differentiable", False)
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def _init_group(self, group, params_with_grad, grads, square_avgs, momentum_buffer_list, grad_avgs):
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has_complex = False
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for p in group["params"]:
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if p.grad is None:
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continue
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has_complex |= torch.is_complex(p)
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params_with_grad.append(p)
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if p.grad.is_sparse:
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raise RuntimeError("RMSprop does not support sparse gradients")
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grads.append(p.grad)
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state = self.state[p]
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# State initialization
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if len(state) == 0:
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state["step"] = 0
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state["square_avg"] = torch.zeros_like(
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p, memory_format=torch.preserve_format
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)
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if group["momentum"] > 0:
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state["momentum_buffer"] = torch.zeros_like(
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p, memory_format=torch.preserve_format
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)
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if group["centered"]:
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state["grad_avg"] = torch.zeros_like(
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p, memory_format=torch.preserve_format
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)
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square_avgs.append(state["square_avg"])
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if group["momentum"] > 0:
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momentum_buffer_list.append(state["momentum_buffer"])
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if group["centered"]:
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grad_avgs.append(state["grad_avg"])
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if group["differentiable"] and isinstance(state["step"], Tensor):
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raise RuntimeError("`step` can't be a tensor")
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state["step"] += 1
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return has_complex
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@_use_grad_for_differentiable
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def step(self, closure=None):
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"""Performs a single optimization step.
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Args:
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closure (Callable, optional): A closure that reevaluates the model
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and returns the loss.
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"""
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loss = None
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if closure is not None:
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with torch.enable_grad():
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loss = closure()
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for group in self.param_groups:
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params_with_grad = []
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grads = []
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square_avgs = []
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grad_avgs = []
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momentum_buffer_list = []
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has_complex = self._init_group(group, params_with_grad, grads, square_avgs, momentum_buffer_list, grad_avgs)
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rmsprop(
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params_with_grad,
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grads,
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square_avgs,
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grad_avgs,
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momentum_buffer_list,
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lr=group["lr"],
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alpha=group["alpha"],
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eps=group["eps"],
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weight_decay=group["weight_decay"],
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momentum=group["momentum"],
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centered=group["centered"],
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foreach=group["foreach"],
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maximize=group["maximize"],
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differentiable=group["differentiable"],
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has_complex=has_complex,
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)
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return loss
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RMSprop.__doc__ = r"""Implements RMSprop algorithm.
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.. math::
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\begin{aligned}
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&\rule{110mm}{0.4pt} \\
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&\textbf{input} : \alpha \text{ (alpha)},\: \gamma \text{ (lr)},
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\: \theta_0 \text{ (params)}, \: f(\theta) \text{ (objective)} \\
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&\hspace{13mm} \lambda \text{ (weight decay)},\: \mu \text{ (momentum)},\: centered\\
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&\textbf{initialize} : v_0 \leftarrow 0 \text{ (square average)}, \:
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\textbf{b}_0 \leftarrow 0 \text{ (buffer)}, \: g^{ave}_0 \leftarrow 0 \\[-1.ex]
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&\rule{110mm}{0.4pt} \\
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&\textbf{for} \: t=1 \: \textbf{to} \: \ldots \: \textbf{do} \\
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&\hspace{5mm}g_t \leftarrow \nabla_{\theta} f_t (\theta_{t-1}) \\
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&\hspace{5mm}if \: \lambda \neq 0 \\
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&\hspace{10mm} g_t \leftarrow g_t + \lambda \theta_{t-1} \\
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&\hspace{5mm}v_t \leftarrow \alpha v_{t-1} + (1 - \alpha) g^2_t
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\hspace{8mm} \\
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&\hspace{5mm} \tilde{v_t} \leftarrow v_t \\
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&\hspace{5mm}if \: centered \\
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&\hspace{10mm} g^{ave}_t \leftarrow g^{ave}_{t-1} \alpha + (1-\alpha) g_t \\
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&\hspace{10mm} \tilde{v_t} \leftarrow \tilde{v_t} - \big(g^{ave}_{t} \big)^2 \\
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&\hspace{5mm}if \: \mu > 0 \\
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&\hspace{10mm} \textbf{b}_t\leftarrow \mu \textbf{b}_{t-1} +
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g_t/ \big(\sqrt{\tilde{v_t}} + \epsilon \big) \\
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&\hspace{10mm} \theta_t \leftarrow \theta_{t-1} - \gamma \textbf{b}_t \\
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&\hspace{5mm} else \\
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&\hspace{10mm}\theta_t \leftarrow \theta_{t-1} -
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\gamma g_t/ \big(\sqrt{\tilde{v_t}} + \epsilon \big) \hspace{3mm} \\
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&\rule{110mm}{0.4pt} \\[-1.ex]
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&\bf{return} \: \theta_t \\[-1.ex]
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&\rule{110mm}{0.4pt} \\[-1.ex]
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\end{aligned}
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For further details regarding the algorithm we refer to
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`lecture notes <https://www.cs.toronto.edu/~tijmen/csc321/slides/lecture_slides_lec6.pdf>`_ by G. Hinton.
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and centered version `Generating Sequences
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With Recurrent Neural Networks <https://arxiv.org/pdf/1308.0850v5.pdf>`_.
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The implementation here takes the square root of the gradient average before
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adding epsilon (note that TensorFlow interchanges these two operations). The effective
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learning rate is thus :math:`\gamma/(\sqrt{v} + \epsilon)` where :math:`\gamma`
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is the scheduled learning rate and :math:`v` is the weighted moving average
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of the squared gradient.
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""" + fr"""
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Args:
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params (iterable): iterable of parameters to optimize or dicts defining
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parameter groups
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lr (float, optional): learning rate (default: 1e-2)
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momentum (float, optional): momentum factor (default: 0)
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alpha (float, optional): smoothing constant (default: 0.99)
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eps (float, optional): term added to the denominator to improve
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numerical stability (default: 1e-8)
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centered (bool, optional) : if ``True``, compute the centered RMSProp,
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the gradient is normalized by an estimation of its variance
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weight_decay (float, optional): weight decay (L2 penalty) (default: 0)
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{_foreach_doc}
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{_maximize_doc}
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{_differentiable_doc}
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"""
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def rmsprop(
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params: List[Tensor],
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grads: List[Tensor],
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square_avgs: List[Tensor],
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grad_avgs: List[Tensor],
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momentum_buffer_list: List[Tensor],
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# kwonly args with defaults are not supported by functions compiled with torchscript issue #70627
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# setting this as kwarg for now as functional API is compiled by torch/distributed/optim
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foreach: Optional[bool] = None,
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maximize: bool = False,
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differentiable: bool = False,
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has_complex: bool = False,
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*,
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lr: float,
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alpha: float,
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eps: float,
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weight_decay: float,
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momentum: float,
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centered: bool,
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):
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r"""Functional API that performs rmsprop algorithm computation.
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See :class:`~torch.optim.RMSProp` for details.
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"""
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if foreach is None:
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_, foreach = _default_to_fused_or_foreach(params, differentiable, use_fused=False)
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if foreach and torch.jit.is_scripting():
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raise RuntimeError("torch.jit.script not supported with foreach optimizers")
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if foreach and not torch.jit.is_scripting():
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func = _multi_tensor_rmsprop
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else:
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func = _single_tensor_rmsprop
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func(
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params,
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grads,
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square_avgs,
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grad_avgs,
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momentum_buffer_list,
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lr=lr,
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alpha=alpha,
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eps=eps,
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weight_decay=weight_decay,
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momentum=momentum,
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centered=centered,
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maximize=maximize,
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differentiable=differentiable,
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has_complex=has_complex,
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)
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def _single_tensor_rmsprop(
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params: List[Tensor],
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grads: List[Tensor],
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square_avgs: List[Tensor],
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grad_avgs: List[Tensor],
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momentum_buffer_list: List[Tensor],
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*,
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lr: float,
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alpha: float,
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eps: float,
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weight_decay: float,
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momentum: float,
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centered: bool,
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maximize: bool,
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differentiable: bool,
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has_complex: bool,
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):
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for i, param in enumerate(params):
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grad = grads[i]
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grad = grad if not maximize else -grad
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square_avg = square_avgs[i]
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if weight_decay != 0:
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grad = grad.add(param, alpha=weight_decay)
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is_complex_param = torch.is_complex(param)
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if is_complex_param:
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param = torch.view_as_real(param)
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grad = torch.view_as_real(grad)
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square_avg = torch.view_as_real(square_avg)
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square_avg.mul_(alpha).addcmul_(grad, grad, value=1 - alpha)
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if centered:
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grad_avg = grad_avgs[i]
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if is_complex_param:
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grad_avg = torch.view_as_real(grad_avg)
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grad_avg.lerp_(grad, 1 - alpha)
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avg = square_avg.addcmul(grad_avg, grad_avg, value=-1).sqrt_()
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else:
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avg = square_avg.sqrt()
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if differentiable:
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avg = avg.add(eps)
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else:
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avg = avg.add_(eps)
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if momentum > 0:
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buf = momentum_buffer_list[i]
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if is_complex_param:
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buf = torch.view_as_real(buf)
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buf.mul_(momentum).addcdiv_(grad, avg)
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param.add_(buf, alpha=-lr)
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else:
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param.addcdiv_(grad, avg, value=-lr)
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def _multi_tensor_rmsprop(
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params: List[Tensor],
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grads: List[Tensor],
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square_avgs: List[Tensor],
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grad_avgs: List[Tensor],
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momentum_buffer_list: List[Tensor],
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*,
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lr: float,
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alpha: float,
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eps: float,
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weight_decay: float,
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momentum: float,
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centered: bool,
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maximize: bool,
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differentiable: bool,
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has_complex: bool,
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):
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if len(params) == 0:
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return
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assert not differentiable, "_foreach ops don't support autograd"
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grouped_tensors = Optimizer._group_tensors_by_device_and_dtype([params, grads, square_avgs, grad_avgs, momentum_buffer_list])
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for (((grouped_params, grouped_grads, grouped_square_avgs, grouped_grad_avgs,
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grouped_momentum_buffer_list)), _) in grouped_tensors.values():
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if has_complex:
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state_and_grads = [grouped_grads, grouped_square_avgs]
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if momentum > 0:
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state_and_grads.append(grouped_momentum_buffer_list)
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if centered:
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state_and_grads.append(grouped_grad_avgs)
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_view_as_real(grouped_params, *state_and_grads)
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if maximize:
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grouped_grads = torch._foreach_neg(grouped_grads)
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if weight_decay != 0:
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# Re-use the intermediate memory (grouped_grads) already allocated for maximize
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if maximize:
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torch._foreach_add_(grouped_grads, grouped_params, alpha=weight_decay)
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else:
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grouped_grads = torch._foreach_add(grouped_grads, grouped_params, alpha=weight_decay)
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torch._foreach_mul_(grouped_square_avgs, alpha)
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torch._foreach_addcmul_(grouped_square_avgs, grouped_grads, grouped_grads, value=1 - alpha)
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if centered:
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torch._foreach_lerp_(grouped_grad_avgs, grouped_grads, 1 - alpha)
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||
|
|
avg = torch._foreach_addcmul(grouped_square_avgs, grouped_grad_avgs, grouped_grad_avgs, value=-1)
|
||
|
|
torch._foreach_sqrt_(avg)
|
||
|
|
torch._foreach_add_(avg, eps)
|
||
|
|
else:
|
||
|
|
avg = torch._foreach_sqrt(grouped_square_avgs)
|
||
|
|
torch._foreach_add_(avg, eps)
|
||
|
|
|
||
|
|
if momentum > 0:
|
||
|
|
torch._foreach_mul_(grouped_momentum_buffer_list, momentum)
|
||
|
|
torch._foreach_addcdiv_(grouped_momentum_buffer_list, grouped_grads, avg)
|
||
|
|
torch._foreach_add_(grouped_params, grouped_momentum_buffer_list, alpha=-lr)
|
||
|
|
else:
|
||
|
|
torch._foreach_addcdiv_(grouped_params, grouped_grads, avg, value=-lr)
|