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Source code for ding.rl_utils.value_rescale

import torch


[docs]def value_transform(x: torch.Tensor, eps: float = 1e-2) -> torch.Tensor: """ Overview: A function to reduce the scale of the action-value function. :math: `h(x) = sign(x)(\sqrt{(abs(x)+1)} - 1) + \epsilon * x` . Arguments: - x: (:obj:`torch.Tensor`) The input tensor to be normalized. - eps: (:obj:`float`) The coefficient of the additive regularization term \ to ensure inverse function is Lipschitz continuous Returns: - (:obj:`torch.Tensor`) Normalized tensor. .. note:: Observe and Look Further: Achieving Consistent Performance on Atari (https://arxiv.org/abs/1805.11593). """ return torch.sign(x) * (torch.sqrt(torch.abs(x) + 1) - 1) + eps * x
[docs]def value_inv_transform(x: torch.Tensor, eps: float = 1e-2) -> torch.Tensor: """ Overview: The inverse form of value rescale. :math: `h^{-1}(x) = sign(x)({(\frac{\sqrt{1+4\epsilon(|x|+1+\epsilon)}-1}{2\epsilon})}^2-1)` . Arguments: - x: (:obj:`torch.Tensor`) The input tensor to be unnormalized. - eps: (:obj:`float`) The coefficient of the additive regularization term \ to ensure inverse function is Lipschitz continuous Returns: - (:obj:`torch.Tensor`) Unnormalized tensor. """ return torch.sign(x) * (((torch.sqrt(1 + 4 * eps * (torch.abs(x) + 1 + eps)) - 1) / (2 * eps)) ** 2 - 1)
[docs]def symlog(x: torch.Tensor) -> torch.Tensor: """ Overview: A function to normalize the targets. :math: `symlog(x) = sign(x)(\ln{|x|+1})` . Arguments: - x: (:obj:`torch.Tensor`) The input tensor to be normalized. Returns: - (:obj:`torch.Tensor`) Normalized tensor. .. note:: Mastering Diverse Domains through World Models (https://arxiv.org/abs/2301.04104) """ return torch.sign(x) * (torch.log(torch.abs(x) + 1))
[docs]def inv_symlog(x: torch.Tensor) -> torch.Tensor: """ Overview: The inverse form of symlog. :math: `symexp(x) = sign(x)(\exp{|x|}-1)` . Arguments: - x: (:obj:`torch.Tensor`) The input tensor to be unnormalized. Returns: - (:obj:`torch.Tensor`) Unnormalized tensor. """ return torch.sign(x) * (torch.exp(torch.abs(x)) - 1)