from typing import Optional
import torch
from torch import Tensor
[docs]def mask_select(src: Tensor, dim: int, mask: Tensor) -> Tensor:
r"""Returns a new tensor which masks the :obj:`src` tensor along the
dimension :obj:`dim` according to the boolean mask :obj:`mask`.
Args:
src (torch.Tensor): The input tensor.
dim (int): The dimension in which to mask.
mask (torch.BoolTensor): The 1-D tensor containing the binary mask to
index with.
"""
assert mask.dim() == 1
assert src.size(dim) == mask.numel()
dim = dim + src.dim() if dim < 0 else dim
assert dim >= 0 and dim < src.dim()
size = [1] * src.dim()
size[dim] = mask.numel()
out = src.masked_select(mask.view(size))
size = list(src.size())
size[dim] = -1
return out.view(size)
[docs]def index_to_mask(index: Tensor, size: Optional[int] = None) -> Tensor:
r"""Converts indices to a mask representation.
Args:
idx (Tensor): The indices.
size (int, optional). The size of the mask. If set to :obj:`None`, a
minimal sized output mask is returned.
Example:
>>> index = torch.tensor([1, 3, 5])
>>> index_to_mask(index)
tensor([False, True, False, True, False, True])
>>> index_to_mask(index, size=7)
tensor([False, True, False, True, False, True, False])
"""
index = index.view(-1)
size = int(index.max()) + 1 if size is None else size
mask = index.new_zeros(size, dtype=torch.bool)
mask[index] = True
return mask
[docs]def mask_to_index(mask: Tensor) -> Tensor:
r"""Converts a mask to an index representation.
Args:
mask (Tensor): The mask.
Example:
>>> mask = torch.tensor([False, True, False])
>>> mask_to_index(mask)
tensor([1])
"""
return mask.nonzero(as_tuple=False).view(-1)