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ca7299e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | # Copyright 2021 AlQuraishi Laboratory
# Copyright 2021 DeepMind Technologies Limited
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from functools import partialmethod, partial
import math
from typing import Optional, List
import torch
import torch.nn as nn
from openfold.model.primitives import Linear, LayerNorm, Attention
from openfold.utils.tensor_utils import (
chunk_layer,
permute_final_dims,
flatten_final_dims,
)
class TriangleAttention(nn.Module):
def __init__(
self, c_in, c_hidden, no_heads, starting, inf=1e9
):
"""
Args:
c_in:
Input channel dimension
c_hidden:
Overall hidden channel dimension (not per-head)
no_heads:
Number of attention heads
"""
super(TriangleAttention, self).__init__()
self.c_in = c_in
self.c_hidden = c_hidden
self.no_heads = no_heads
self.starting = starting
self.inf = inf
self.layer_norm = LayerNorm(self.c_in)
self.linear = Linear(c_in, self.no_heads, bias=False, init="normal")
self.mha = Attention(
self.c_in, self.c_in, self.c_in, self.c_hidden, self.no_heads
)
@torch.jit.ignore
def _chunk(self,
x: torch.Tensor,
biases: List[torch.Tensor],
chunk_size: int,
) -> torch.Tensor:
mha_inputs = {
"q_x": x,
"kv_x": x,
"biases": biases,
}
return chunk_layer(
partial(self.mha),
mha_inputs,
chunk_size=chunk_size,
no_batch_dims=len(x.shape[:-2]),
)
def forward(self,
x: torch.Tensor,
mask: Optional[torch.Tensor] = None,
chunk_size: Optional[int] = None
) -> torch.Tensor:
"""
Args:
x:
[*, I, J, C_in] input tensor (e.g. the pair representation)
Returns:
[*, I, J, C_in] output tensor
"""
if mask is None:
# [*, I, J]
mask = x.new_ones(
x.shape[:-1],
)
# Shape annotations assume self.starting. Else, I and J are flipped
if not self.starting:
x = x.transpose(-2, -3)
mask = mask.transpose(-1, -2)
# [*, I, J, C_in]
x = self.layer_norm(x)
# [*, I, 1, 1, J]
mask_bias = (self.inf * (mask - 1))[..., :, None, None, :]
# [*, H, I, J]
triangle_bias = permute_final_dims(self.linear(x), (2, 0, 1))
# [*, 1, H, I, J]
triangle_bias = triangle_bias.unsqueeze(-4)
biases = [mask_bias, triangle_bias]
if chunk_size is not None:
x = self._chunk(x, biases, chunk_size)
else:
x = self.mha(q_x=x, kv_x=x, biases=biases)
if not self.starting:
x = x.transpose(-2, -3)
return x
class TriangleAttentionStartingNode(TriangleAttention):
"""
Implements Algorithm 13.
"""
__init__ = partialmethod(TriangleAttention.__init__, starting=True)
class TriangleAttentionEndingNode(TriangleAttention):
"""
Implements Algorithm 14.
"""
__init__ = partialmethod(TriangleAttention.__init__, starting=False)
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