pytorch/torch/nn/modules/distance.py
Edward Yang 173f224570 Turn on F401: Unused import warning. (#18598)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18598
ghimport-source-id: c74597e5e7437e94a43c163cee0639b20d0d0c6a

Stack from [ghstack](https://github.com/ezyang/ghstack):
* **#18598 Turn on F401: Unused import warning.**

This was requested by someone at Facebook; this lint is turned
on for Facebook by default.  "Sure, why not."

I had to noqa a number of imports in __init__.  Hypothetically
we're supposed to use __all__ in this case, but I was too lazy
to fix it.  Left for future work.

Be careful!  flake8-2 and flake8-3 behave differently with
respect to import resolution for # type: comments.  flake8-3 will
report an import unused; flake8-2 will not.  For now, I just
noqa'd all these sites.

All the changes were done by hand.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Differential Revision: D14687478

fbshipit-source-id: 30d532381e914091aadfa0d2a5a89404819663e3
2019-03-30 09:01:17 -07:00

80 lines
2.5 KiB
Python

from .module import Module
from .. import functional as F
from ..._jit_internal import weak_module, weak_script_method
@weak_module
class PairwiseDistance(Module):
r"""
Computes the batchwise pairwise distance between vectors :math:`v_1`, :math:`v_2` using the p-norm:
.. math ::
\Vert x \Vert _p = \left( \sum_{i=1}^n \vert x_i \vert ^ p \right) ^ {1/p}
Args:
p (real): the norm degree. Default: 2
eps (float, optional): Small value to avoid division by zero.
Default: 1e-6
keepdim (bool, optional): Determines whether or not to keep the batch dimension.
Default: False
Shape:
- Input1: :math:`(N, D)` where `D = vector dimension`
- Input2: :math:`(N, D)`, same shape as the Input1
- Output: :math:`(N)`. If :attr:`keepdim` is ``False``, then :math:`(N, 1)`.
Examples::
>>> pdist = nn.PairwiseDistance(p=2)
>>> input1 = torch.randn(100, 128)
>>> input2 = torch.randn(100, 128)
>>> output = pdist(input1, input2)
"""
__constants__ = ['norm', 'eps', 'keepdim']
def __init__(self, p=2., eps=1e-6, keepdim=False):
super(PairwiseDistance, self).__init__()
self.norm = p
self.eps = eps
self.keepdim = keepdim
@weak_script_method
def forward(self, x1, x2):
return F.pairwise_distance(x1, x2, self.norm, self.eps, self.keepdim)
@weak_module
class CosineSimilarity(Module):
r"""Returns cosine similarity between :math:`x_1` and :math:`x_2`, computed along dim.
.. math ::
\text{similarity} = \dfrac{x_1 \cdot x_2}{\max(\Vert x_1 \Vert _2 \cdot \Vert x_2 \Vert _2, \epsilon)}
Args:
dim (int, optional): Dimension where cosine similarity is computed. Default: 1
eps (float, optional): Small value to avoid division by zero.
Default: 1e-8
Shape:
- Input1: :math:`(\ast_1, D, \ast_2)` where D is at position `dim`
- Input2: :math:`(\ast_1, D, \ast_2)`, same shape as the Input1
- Output: :math:`(\ast_1, \ast_2)`
Examples::
>>> input1 = torch.randn(100, 128)
>>> input2 = torch.randn(100, 128)
>>> cos = nn.CosineSimilarity(dim=1, eps=1e-6)
>>> output = cos(input1, input2)
"""
__constants__ = ['dim', 'eps']
def __init__(self, dim=1, eps=1e-8):
super(CosineSimilarity, self).__init__()
self.dim = dim
self.eps = eps
@weak_script_method
def forward(self, x1, x2):
return F.cosine_similarity(x1, x2, self.dim, self.eps)