drmsd（distance Root Mean Square Deviation，距离均方根偏差）函数在AlphaFold3的 src.utils.validation_metrics模块中定义，用于计算两个蛋白质结构（或其他分子结构）之间的距离偏差。它衡量了两个结构的 成对原子间距离 差异，而不是直接比较原子坐标。这种度量方式比 RMSD（Root Mean Square Deviation，均方根偏差）更能反映全局结构差异，因为它不会受到全局对齐的影响。

源代码：

import torch
from typing import Optionaldef drmsd(structure_1: torch.Tensor, structure_2: torch.Tensor, mask: Optional[torch.Tensor] = None) -> torch.Tensor:"""Calculate the distance Root Mean Square Deviation (dRMSD) between two structures.Args:structure_1 (torch.Tensor): First structure of shape [..., N, 3]structure_2 (torch.Tensor): Second structure of shape [..., N, 3]mask (Optional[torch.Tensor]): Mask of shape [..., N] indicating valid positionsReturns:torch.Tensor: The dRMSD between the two structures"""def pairwise_distances(structure: torch.Tensor) -> torch.Tensor:"""Calculate pairwise distances within a structure."""diff = structure[..., :, None, :] - structure[..., None, :, :]return torch.norm(diff, dim=-1)d1 = pairwise_dis