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-# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
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-#
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-# Licensed under the Apache License, Version 2.0 (the "License");
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-# you may not use this file except in compliance with the License.
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-# You may obtain a copy of the License at
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-#
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-# http://www.apache.org/licenses/LICENSE-2.0
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-#
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-# Unless required by applicable law or agreed to in writing, software
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-# distributed under the License is distributed on an "AS IS" BASIS,
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-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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-# See the License for the specific language governing permissions and
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-# limitations under the License.
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-
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-import paddle
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-import paddle.nn as nn
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-import paddle.nn.functional as F
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-from paddle.nn.initializer import TruncatedNormal, Constant, Assign
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-from paddlex.ppdet.modeling.shape_spec import ShapeSpec
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-from paddlex.ppdet.core.workspace import register, serializable
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-import numpy as np
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-
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-# Common initializations
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-ones_ = Constant(value=1.)
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-zeros_ = Constant(value=0.)
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-trunc_normal_ = TruncatedNormal(std=.02)
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-
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-
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-# Common Functions
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-def to_2tuple(x):
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- return tuple([x] * 2)
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-
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-
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-def add_parameter(layer, datas, name=None):
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- parameter = layer.create_parameter(
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- shape=(datas.shape), default_initializer=Assign(datas))
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- if name:
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- layer.add_parameter(name, parameter)
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- return parameter
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-
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-
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-# Common Layers
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-def drop_path(x, drop_prob=0., training=False):
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- """
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- Drop paths (Stochastic Depth) per sample (when applied in main path of residual blocks).
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- the original name is misleading as 'Drop Connect' is a different form of dropout in a separate paper...
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- See discussion: https://github.com/tensorflow/tpu/issues/494#issuecomment-532968956 ...
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- """
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- if drop_prob == 0. or not training:
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- return x
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- keep_prob = paddle.to_tensor(1 - drop_prob)
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- shape = (paddle.shape(x)[0], ) + (1, ) * (x.ndim - 1)
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- random_tensor = keep_prob + paddle.rand(shape, dtype=x.dtype)
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- random_tensor = paddle.floor(random_tensor) # binarize
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- output = x.divide(keep_prob) * random_tensor
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- return output
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-
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-
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-class DropPath(nn.Layer):
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- def __init__(self, drop_prob=None):
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- super(DropPath, self).__init__()
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- self.drop_prob = drop_prob
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-
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- def forward(self, x):
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- return drop_path(x, self.drop_prob, self.training)
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-
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-
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-class Identity(nn.Layer):
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- def __init__(self):
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- super(Identity, self).__init__()
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-
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- def forward(self, input):
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- return input
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-
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-
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-class Mlp(nn.Layer):
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- def __init__(self,
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- in_features,
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- hidden_features=None,
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- out_features=None,
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- act_layer=nn.GELU,
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- drop=0.):
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- super().__init__()
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- out_features = out_features or in_features
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- hidden_features = hidden_features or in_features
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- self.fc1 = nn.Linear(in_features, hidden_features)
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- self.act = act_layer()
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- self.fc2 = nn.Linear(hidden_features, out_features)
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- self.drop = nn.Dropout(drop)
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-
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- def forward(self, x):
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- x = self.fc1(x)
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- x = self.act(x)
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- x = self.drop(x)
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- x = self.fc2(x)
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- x = self.drop(x)
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- return x
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-
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-
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-def window_partition(x, window_size):
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- """
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- Args:
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- x: (B, H, W, C)
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- window_size (int): window size
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- Returns:
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- windows: (num_windows*B, window_size, window_size, C)
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- """
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- B, H, W, C = x.shape
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- x = x.reshape(
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- [B, H // window_size, window_size, W // window_size, window_size, C])
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- windows = x.transpose([0, 1, 3, 2, 4, 5]).reshape(
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- [-1, window_size, window_size, C])
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- return windows
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-
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-
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-def window_reverse(windows, window_size, H, W):
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- """
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- Args:
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- windows: (num_windows*B, window_size, window_size, C)
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- window_size (int): Window size
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- H (int): Height of image
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- W (int): Width of image
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- Returns:
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- x: (B, H, W, C)
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- """
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- B = int(windows.shape[0] / (H * W / window_size / window_size))
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- x = windows.reshape(
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- [B, H // window_size, W // window_size, window_size, window_size, -1])
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- x = x.transpose([0, 1, 3, 2, 4, 5]).reshape([B, H, W, -1])
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- return x
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-
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-
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-class WindowAttention(nn.Layer):
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- """ Window based multi-head self attention (W-MSA) module with relative position bias.
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- It supports both of shifted and non-shifted window.
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-
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- Args:
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- dim (int): Number of input channels.
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- window_size (tuple[int]): The height and width of the window.
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- num_heads (int): Number of attention heads.
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- qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
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- qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set
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- attn_drop (float, optional): Dropout ratio of attention weight. Default: 0.0
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- proj_drop (float, optional): Dropout ratio of output. Default: 0.0
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- """
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-
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- def __init__(self,
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- dim,
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- window_size,
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- num_heads,
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- qkv_bias=True,
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- qk_scale=None,
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- attn_drop=0.,
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- proj_drop=0.):
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-
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- super().__init__()
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- self.dim = dim
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- self.window_size = window_size # Wh, Ww
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- self.num_heads = num_heads
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- head_dim = dim // num_heads
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- self.scale = qk_scale or head_dim**-0.5
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-
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- # define a parameter table of relative position bias
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- self.relative_position_bias_table = add_parameter(
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- self,
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- paddle.zeros(((2 * window_size[0] - 1) * (2 * window_size[1] - 1),
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- num_heads))) # 2*Wh-1 * 2*Ww-1, nH
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-
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- # get pair-wise relative position index for each token inside the window
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- coords_h = paddle.arange(self.window_size[0])
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- coords_w = paddle.arange(self.window_size[1])
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- coords = paddle.stack(paddle.meshgrid(
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- [coords_h, coords_w])) # 2, Wh, Ww
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- coords_flatten = paddle.flatten(coords, 1) # 2, Wh*Ww
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- coords_flatten_1 = coords_flatten.unsqueeze(axis=2)
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- coords_flatten_2 = coords_flatten.unsqueeze(axis=1)
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- relative_coords = coords_flatten_1 - coords_flatten_2
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- relative_coords = relative_coords.transpose(
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- [1, 2, 0]) # Wh*Ww, Wh*Ww, 2
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- relative_coords[:, :, 0] += self.window_size[
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- 0] - 1 # shift to start from 0
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- relative_coords[:, :, 1] += self.window_size[1] - 1
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- relative_coords[:, :, 0] *= 2 * self.window_size[1] - 1
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- self.relative_position_index = relative_coords.sum(-1) # Wh*Ww, Wh*Ww
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- self.register_buffer("relative_position_index",
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- self.relative_position_index)
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-
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- self.qkv = nn.Linear(dim, dim * 3, bias_attr=qkv_bias)
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- self.attn_drop = nn.Dropout(attn_drop)
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- self.proj = nn.Linear(dim, dim)
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- self.proj_drop = nn.Dropout(proj_drop)
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-
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- trunc_normal_(self.relative_position_bias_table)
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- self.softmax = nn.Softmax(axis=-1)
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-
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- def forward(self, x, mask=None):
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- """ Forward function.
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- Args:
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- x: input features with shape of (num_windows*B, N, C)
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- mask: (0/-inf) mask with shape of (num_windows, Wh*Ww, Wh*Ww) or None
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- """
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- B_, N, C = x.shape
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- qkv = self.qkv(x).reshape(
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- [B_, N, 3, self.num_heads, C // self.num_heads]).transpose(
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- [2, 0, 3, 1, 4])
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- q, k, v = qkv[0], qkv[1], qkv[2]
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-
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- q = q * self.scale
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- attn = paddle.mm(q, k.transpose([0, 1, 3, 2]))
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-
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- index = self.relative_position_index.reshape([-1])
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-
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- relative_position_bias = paddle.index_select(
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- self.relative_position_bias_table, index)
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- relative_position_bias = relative_position_bias.reshape([
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- self.window_size[0] * self.window_size[1],
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- self.window_size[0] * self.window_size[1], -1
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- ]) # Wh*Ww,Wh*Ww,nH
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- relative_position_bias = relative_position_bias.transpose(
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- [2, 0, 1]) # nH, Wh*Ww, Wh*Ww
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- attn = attn + relative_position_bias.unsqueeze(0)
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-
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- if mask is not None:
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- nW = mask.shape[0]
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- attn = attn.reshape([B_ // nW, nW, self.num_heads, N, N
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- ]) + mask.unsqueeze(1).unsqueeze(0)
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- attn = attn.reshape([-1, self.num_heads, N, N])
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- attn = self.softmax(attn)
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- else:
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- attn = self.softmax(attn)
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-
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- attn = self.attn_drop(attn)
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-
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- # x = (attn @ v).transpose(1, 2).reshape([B_, N, C])
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- x = paddle.mm(attn, v).transpose([0, 2, 1, 3]).reshape([B_, N, C])
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- x = self.proj(x)
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- x = self.proj_drop(x)
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- return x
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-
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-
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-class SwinTransformerBlock(nn.Layer):
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- """ Swin Transformer Block.
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- Args:
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- dim (int): Number of input channels.
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- num_heads (int): Number of attention heads.
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- window_size (int): Window size.
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- shift_size (int): Shift size for SW-MSA.
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- mlp_ratio (float): Ratio of mlp hidden dim to embedding dim.
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- qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
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- qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
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- drop (float, optional): Dropout rate. Default: 0.0
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- attn_drop (float, optional): Attention dropout rate. Default: 0.0
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- drop_path (float, optional): Stochastic depth rate. Default: 0.0
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- act_layer (nn.Layer, optional): Activation layer. Default: nn.GELU
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- norm_layer (nn.Layer, optional): Normalization layer. Default: nn.LayerNorm
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- """
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-
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- def __init__(self,
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- dim,
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- num_heads,
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- window_size=7,
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- shift_size=0,
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- mlp_ratio=4.,
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- qkv_bias=True,
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- qk_scale=None,
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- drop=0.,
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- attn_drop=0.,
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- drop_path=0.,
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- act_layer=nn.GELU,
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- norm_layer=nn.LayerNorm):
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- super().__init__()
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- self.dim = dim
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- self.num_heads = num_heads
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- self.window_size = window_size
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- self.shift_size = shift_size
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- self.mlp_ratio = mlp_ratio
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- assert 0 <= self.shift_size < self.window_size, "shift_size must in 0-window_size"
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-
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- self.norm1 = norm_layer(dim)
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- self.attn = WindowAttention(
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- dim,
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- window_size=to_2tuple(self.window_size),
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- num_heads=num_heads,
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- qkv_bias=qkv_bias,
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- qk_scale=qk_scale,
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- attn_drop=attn_drop,
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- proj_drop=drop)
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-
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- self.drop_path = DropPath(drop_path) if drop_path > 0. else Identity()
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- self.norm2 = norm_layer(dim)
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- mlp_hidden_dim = int(dim * mlp_ratio)
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- self.mlp = Mlp(in_features=dim,
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|
|
- hidden_features=mlp_hidden_dim,
|
|
|
|
|
- act_layer=act_layer,
|
|
|
|
|
- drop=drop)
|
|
|
|
|
-
|
|
|
|
|
- self.H = None
|
|
|
|
|
- self.W = None
|
|
|
|
|
-
|
|
|
|
|
- def forward(self, x, mask_matrix):
|
|
|
|
|
- """ Forward function.
|
|
|
|
|
- Args:
|
|
|
|
|
- x: Input feature, tensor size (B, H*W, C).
|
|
|
|
|
- H, W: Spatial resolution of the input feature.
|
|
|
|
|
- mask_matrix: Attention mask for cyclic shift.
|
|
|
|
|
- """
|
|
|
|
|
- B, L, C = x.shape
|
|
|
|
|
- H, W = self.H, self.W
|
|
|
|
|
- assert L == H * W, "input feature has wrong size"
|
|
|
|
|
-
|
|
|
|
|
- shortcut = x
|
|
|
|
|
- x = self.norm1(x)
|
|
|
|
|
- x = x.reshape([B, H, W, C])
|
|
|
|
|
-
|
|
|
|
|
- # pad feature maps to multiples of window size
|
|
|
|
|
- pad_l = pad_t = 0
|
|
|
|
|
- pad_r = (self.window_size - W % self.window_size) % self.window_size
|
|
|
|
|
- pad_b = (self.window_size - H % self.window_size) % self.window_size
|
|
|
|
|
- x = F.pad(x, [0, pad_l, 0, pad_b, 0, pad_r, 0, pad_t])
|
|
|
|
|
- _, Hp, Wp, _ = x.shape
|
|
|
|
|
-
|
|
|
|
|
- # cyclic shift
|
|
|
|
|
- if self.shift_size > 0:
|
|
|
|
|
- shifted_x = paddle.roll(
|
|
|
|
|
- x, shifts=(-self.shift_size, -self.shift_size), axis=(1, 2))
|
|
|
|
|
- attn_mask = mask_matrix
|
|
|
|
|
- else:
|
|
|
|
|
- shifted_x = x
|
|
|
|
|
- attn_mask = None
|
|
|
|
|
-
|
|
|
|
|
- # partition windows
|
|
|
|
|
- x_windows = window_partition(
|
|
|
|
|
- shifted_x, self.window_size) # nW*B, window_size, window_size, C
|
|
|
|
|
- x_windows = x_windows.reshape(
|
|
|
|
|
- [-1, self.window_size * self.window_size,
|
|
|
|
|
- C]) # nW*B, window_size*window_size, C
|
|
|
|
|
-
|
|
|
|
|
- # W-MSA/SW-MSA
|
|
|
|
|
- attn_windows = self.attn(
|
|
|
|
|
- x_windows, mask=attn_mask) # nW*B, window_size*window_size, C
|
|
|
|
|
-
|
|
|
|
|
- # merge windows
|
|
|
|
|
- attn_windows = attn_windows.reshape(
|
|
|
|
|
- [-1, self.window_size, self.window_size, C])
|
|
|
|
|
- shifted_x = window_reverse(attn_windows, self.window_size, Hp,
|
|
|
|
|
- Wp) # B H' W' C
|
|
|
|
|
-
|
|
|
|
|
- # reverse cyclic shift
|
|
|
|
|
- if self.shift_size > 0:
|
|
|
|
|
- x = paddle.roll(
|
|
|
|
|
- shifted_x,
|
|
|
|
|
- shifts=(self.shift_size, self.shift_size),
|
|
|
|
|
- axis=(1, 2))
|
|
|
|
|
- else:
|
|
|
|
|
- x = shifted_x
|
|
|
|
|
-
|
|
|
|
|
- if pad_r > 0 or pad_b > 0:
|
|
|
|
|
- x = x[:, :H, :W, :]
|
|
|
|
|
-
|
|
|
|
|
- x = x.reshape([B, H * W, C])
|
|
|
|
|
-
|
|
|
|
|
- # FFN
|
|
|
|
|
- x = shortcut + self.drop_path(x)
|
|
|
|
|
- x = x + self.drop_path(self.mlp(self.norm2(x)))
|
|
|
|
|
-
|
|
|
|
|
- return x
|
|
|
|
|
-
|
|
|
|
|
-
|
|
|
|
|
-class PatchMerging(nn.Layer):
|
|
|
|
|
- r""" Patch Merging Layer.
|
|
|
|
|
- Args:
|
|
|
|
|
- dim (int): Number of input channels.
|
|
|
|
|
- norm_layer (nn.Layer, optional): Normalization layer. Default: nn.LayerNorm
|
|
|
|
|
- """
|
|
|
|
|
-
|
|
|
|
|
- def __init__(self, dim, norm_layer=nn.LayerNorm):
|
|
|
|
|
- super().__init__()
|
|
|
|
|
- self.dim = dim
|
|
|
|
|
- self.reduction = nn.Linear(4 * dim, 2 * dim, bias_attr=False)
|
|
|
|
|
- self.norm = norm_layer(4 * dim)
|
|
|
|
|
-
|
|
|
|
|
- def forward(self, x, H, W):
|
|
|
|
|
- """ Forward function.
|
|
|
|
|
- Args:
|
|
|
|
|
- x: Input feature, tensor size (B, H*W, C).
|
|
|
|
|
- H, W: Spatial resolution of the input feature.
|
|
|
|
|
- """
|
|
|
|
|
- B, L, C = x.shape
|
|
|
|
|
- assert L == H * W, "input feature has wrong size"
|
|
|
|
|
-
|
|
|
|
|
- x = x.reshape([B, H, W, C])
|
|
|
|
|
-
|
|
|
|
|
- # padding
|
|
|
|
|
- pad_input = (H % 2 == 1) or (W % 2 == 1)
|
|
|
|
|
- if pad_input:
|
|
|
|
|
- x = F.pad(x, [0, 0, 0, W % 2, 0, H % 2])
|
|
|
|
|
-
|
|
|
|
|
- x0 = x[:, 0::2, 0::2, :] # B H/2 W/2 C
|
|
|
|
|
- x1 = x[:, 1::2, 0::2, :] # B H/2 W/2 C
|
|
|
|
|
- x2 = x[:, 0::2, 1::2, :] # B H/2 W/2 C
|
|
|
|
|
- x3 = x[:, 1::2, 1::2, :] # B H/2 W/2 C
|
|
|
|
|
- x = paddle.concat([x0, x1, x2, x3], -1) # B H/2 W/2 4*C
|
|
|
|
|
- x = x.reshape([B, H * W // 4, 4 * C]) # B H/2*W/2 4*C
|
|
|
|
|
-
|
|
|
|
|
- x = self.norm(x)
|
|
|
|
|
- x = self.reduction(x)
|
|
|
|
|
-
|
|
|
|
|
- return x
|
|
|
|
|
-
|
|
|
|
|
-
|
|
|
|
|
-class BasicLayer(nn.Layer):
|
|
|
|
|
- """ A basic Swin Transformer layer for one stage.
|
|
|
|
|
- Args:
|
|
|
|
|
- dim (int): Number of input channels.
|
|
|
|
|
- input_resolution (tuple[int]): Input resolution.
|
|
|
|
|
- depth (int): Number of blocks.
|
|
|
|
|
- num_heads (int): Number of attention heads.
|
|
|
|
|
- window_size (int): Local window size.
|
|
|
|
|
- mlp_ratio (float): Ratio of mlp hidden dim to embedding dim.
|
|
|
|
|
- qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
|
|
|
|
|
- qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
|
|
|
|
|
- drop (float, optional): Dropout rate. Default: 0.0
|
|
|
|
|
- attn_drop (float, optional): Attention dropout rate. Default: 0.0
|
|
|
|
|
- drop_path (float | tuple[float], optional): Stochastic depth rate. Default: 0.0
|
|
|
|
|
- norm_layer (nn.Layer, optional): Normalization layer. Default: nn.LayerNorm
|
|
|
|
|
- downsample (nn.Layer | None, optional): Downsample layer at the end of the layer. Default: None
|
|
|
|
|
- """
|
|
|
|
|
-
|
|
|
|
|
- def __init__(self,
|
|
|
|
|
- dim,
|
|
|
|
|
- depth,
|
|
|
|
|
- num_heads,
|
|
|
|
|
- window_size=7,
|
|
|
|
|
- mlp_ratio=4.,
|
|
|
|
|
- qkv_bias=True,
|
|
|
|
|
- qk_scale=None,
|
|
|
|
|
- drop=0.,
|
|
|
|
|
- attn_drop=0.,
|
|
|
|
|
- drop_path=0.,
|
|
|
|
|
- norm_layer=nn.LayerNorm,
|
|
|
|
|
- downsample=None):
|
|
|
|
|
- super().__init__()
|
|
|
|
|
- self.window_size = window_size
|
|
|
|
|
- self.shift_size = window_size // 2
|
|
|
|
|
- self.depth = depth
|
|
|
|
|
-
|
|
|
|
|
- # build blocks
|
|
|
|
|
- self.blocks = nn.LayerList([
|
|
|
|
|
- SwinTransformerBlock(
|
|
|
|
|
- dim=dim,
|
|
|
|
|
- num_heads=num_heads,
|
|
|
|
|
- window_size=window_size,
|
|
|
|
|
- shift_size=0 if (i % 2 == 0) else window_size // 2,
|
|
|
|
|
- mlp_ratio=mlp_ratio,
|
|
|
|
|
- qkv_bias=qkv_bias,
|
|
|
|
|
- qk_scale=qk_scale,
|
|
|
|
|
- drop=drop,
|
|
|
|
|
- attn_drop=attn_drop,
|
|
|
|
|
- drop_path=drop_path[i]
|
|
|
|
|
- if isinstance(drop_path, np.ndarray) else drop_path,
|
|
|
|
|
- norm_layer=norm_layer) for i in range(depth)
|
|
|
|
|
- ])
|
|
|
|
|
-
|
|
|
|
|
- # patch merging layer
|
|
|
|
|
- if downsample is not None:
|
|
|
|
|
- self.downsample = downsample(dim=dim, norm_layer=norm_layer)
|
|
|
|
|
- else:
|
|
|
|
|
- self.downsample = None
|
|
|
|
|
-
|
|
|
|
|
- def forward(self, x, H, W):
|
|
|
|
|
- """ Forward function.
|
|
|
|
|
- Args:
|
|
|
|
|
- x: Input feature, tensor size (B, H*W, C).
|
|
|
|
|
- H, W: Spatial resolution of the input feature.
|
|
|
|
|
- """
|
|
|
|
|
-
|
|
|
|
|
- # calculate attention mask for SW-MSA
|
|
|
|
|
- Hp = int(np.ceil(H / self.window_size)) * self.window_size
|
|
|
|
|
- Wp = int(np.ceil(W / self.window_size)) * self.window_size
|
|
|
|
|
- img_mask = paddle.fluid.layers.zeros(
|
|
|
|
|
- [1, Hp, Wp, 1], dtype='float32') # 1 Hp Wp 1
|
|
|
|
|
- h_slices = (slice(0, -self.window_size),
|
|
|
|
|
- slice(-self.window_size, -self.shift_size),
|
|
|
|
|
- slice(-self.shift_size, None))
|
|
|
|
|
- w_slices = (slice(0, -self.window_size),
|
|
|
|
|
- slice(-self.window_size, -self.shift_size),
|
|
|
|
|
- slice(-self.shift_size, None))
|
|
|
|
|
- cnt = 0
|
|
|
|
|
- for h in h_slices:
|
|
|
|
|
- for w in w_slices:
|
|
|
|
|
- img_mask[:, h, w, :] = cnt
|
|
|
|
|
- cnt += 1
|
|
|
|
|
- mask_windows = window_partition(
|
|
|
|
|
- img_mask, self.window_size) # nW, window_size, window_size, 1
|
|
|
|
|
- mask_windows = mask_windows.reshape(
|
|
|
|
|
- [-1, self.window_size * self.window_size])
|
|
|
|
|
- attn_mask = mask_windows.unsqueeze(1) - mask_windows.unsqueeze(2)
|
|
|
|
|
- huns = -100.0 * paddle.ones_like(attn_mask)
|
|
|
|
|
- attn_mask = huns * (attn_mask != 0).astype("float32")
|
|
|
|
|
-
|
|
|
|
|
- for blk in self.blocks:
|
|
|
|
|
- blk.H, blk.W = H, W
|
|
|
|
|
- x = blk(x, attn_mask)
|
|
|
|
|
- if self.downsample is not None:
|
|
|
|
|
- x_down = self.downsample(x, H, W)
|
|
|
|
|
- Wh, Ww = (H + 1) // 2, (W + 1) // 2
|
|
|
|
|
- return x, H, W, x_down, Wh, Ww
|
|
|
|
|
- else:
|
|
|
|
|
- return x, H, W, x, H, W
|
|
|
|
|
-
|
|
|
|
|
-
|
|
|
|
|
-class PatchEmbed(nn.Layer):
|
|
|
|
|
- """ Image to Patch Embedding
|
|
|
|
|
- Args:
|
|
|
|
|
- patch_size (int): Patch token size. Default: 4.
|
|
|
|
|
- in_chans (int): Number of input image channels. Default: 3.
|
|
|
|
|
- embed_dim (int): Number of linear projection output channels. Default: 96.
|
|
|
|
|
- norm_layer (nn.Layer, optional): Normalization layer. Default: None
|
|
|
|
|
- """
|
|
|
|
|
-
|
|
|
|
|
- def __init__(self, patch_size=4, in_chans=3, embed_dim=96,
|
|
|
|
|
- norm_layer=None):
|
|
|
|
|
- super().__init__()
|
|
|
|
|
- patch_size = to_2tuple(patch_size)
|
|
|
|
|
- self.patch_size = patch_size
|
|
|
|
|
-
|
|
|
|
|
- self.in_chans = in_chans
|
|
|
|
|
- self.embed_dim = embed_dim
|
|
|
|
|
-
|
|
|
|
|
- self.proj = nn.Conv2D(
|
|
|
|
|
- in_chans, embed_dim, kernel_size=patch_size, stride=patch_size)
|
|
|
|
|
- if norm_layer is not None:
|
|
|
|
|
- self.norm = norm_layer(embed_dim)
|
|
|
|
|
- else:
|
|
|
|
|
- self.norm = None
|
|
|
|
|
-
|
|
|
|
|
- def forward(self, x):
|
|
|
|
|
- B, C, H, W = x.shape
|
|
|
|
|
- # assert [H, W] == self.img_size[:2], "Input image size ({H}*{W}) doesn't match model ({}*{}).".format(H, W, self.img_size[0], self.img_size[1])
|
|
|
|
|
- if W % self.patch_size[1] != 0:
|
|
|
|
|
- x = F.pad(x, [0, self.patch_size[1] - W % self.patch_size[1]])
|
|
|
|
|
- if H % self.patch_size[0] != 0:
|
|
|
|
|
- x = F.pad(x,
|
|
|
|
|
- [0, 0, 0, self.patch_size[0] - H % self.patch_size[0]])
|
|
|
|
|
-
|
|
|
|
|
- x = self.proj(x)
|
|
|
|
|
- if self.norm is not None:
|
|
|
|
|
- _, _, Wh, Ww = x.shape
|
|
|
|
|
- x = x.flatten(2).transpose([0, 2, 1])
|
|
|
|
|
- x = self.norm(x)
|
|
|
|
|
- x = x.transpose([0, 2, 1]).reshape([-1, self.embed_dim, Wh, Ww])
|
|
|
|
|
-
|
|
|
|
|
- return x
|
|
|
|
|
-
|
|
|
|
|
-
|
|
|
|
|
-@register
|
|
|
|
|
-@serializable
|
|
|
|
|
-class SwinTransformer(nn.Layer):
|
|
|
|
|
- """ Swin Transformer
|
|
|
|
|
- A PaddlePaddle impl of : `Swin Transformer: Hierarchical Vision Transformer using Shifted Windows` -
|
|
|
|
|
- https://arxiv.org/pdf/2103.14030
|
|
|
|
|
-
|
|
|
|
|
- Args:
|
|
|
|
|
- img_size (int | tuple(int)): Input image size. Default 224
|
|
|
|
|
- patch_size (int | tuple(int)): Patch size. Default: 4
|
|
|
|
|
- in_chans (int): Number of input image channels. Default: 3
|
|
|
|
|
- num_classes (int): Number of classes for classification head. Default: 1000
|
|
|
|
|
- embed_dim (int): Patch embedding dimension. Default: 96
|
|
|
|
|
- depths (tuple(int)): Depth of each Swin Transformer layer.
|
|
|
|
|
- num_heads (tuple(int)): Number of attention heads in different layers.
|
|
|
|
|
- window_size (int): Window size. Default: 7
|
|
|
|
|
- mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4
|
|
|
|
|
- qkv_bias (bool): If True, add a learnable bias to query, key, value. Default: True
|
|
|
|
|
- qk_scale (float): Override default qk scale of head_dim ** -0.5 if set. Default: None
|
|
|
|
|
- drop_rate (float): Dropout rate. Default: 0
|
|
|
|
|
- attn_drop_rate (float): Attention dropout rate. Default: 0
|
|
|
|
|
- drop_path_rate (float): Stochastic depth rate. Default: 0.1
|
|
|
|
|
- norm_layer (nn.Layer): Normalization layer. Default: nn.LayerNorm.
|
|
|
|
|
- ape (bool): If True, add absolute position embedding to the patch embedding. Default: False
|
|
|
|
|
- patch_norm (bool): If True, add normalization after patch embedding. Default: True
|
|
|
|
|
- """
|
|
|
|
|
-
|
|
|
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- def __init__(self,
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- pretrain_img_size=224,
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- patch_size=4,
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- in_chans=3,
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- embed_dim=96,
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- depths=[2, 2, 6, 2],
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- num_heads=[3, 6, 12, 24],
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- window_size=7,
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- mlp_ratio=4.,
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- qkv_bias=True,
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- qk_scale=None,
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- drop_rate=0.,
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- attn_drop_rate=0.,
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- drop_path_rate=0.2,
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- norm_layer=nn.LayerNorm,
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- ape=False,
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- patch_norm=True,
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- out_indices=(0, 1, 2, 3),
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- frozen_stages=-1,
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- pretrained=None):
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- super(SwinTransformer, self).__init__()
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-
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- self.pretrain_img_size = pretrain_img_size
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- self.num_layers = len(depths)
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- self.embed_dim = embed_dim
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- self.ape = ape
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- self.patch_norm = patch_norm
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- self.out_indices = out_indices
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- self.frozen_stages = frozen_stages
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-
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- # split image into non-overlapping patches
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- self.patch_embed = PatchEmbed(
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- patch_size=patch_size,
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- in_chans=in_chans,
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- embed_dim=embed_dim,
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- norm_layer=norm_layer if self.patch_norm else None)
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-
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- # absolute position embedding
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- if self.ape:
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- pretrain_img_size = to_2tuple(pretrain_img_size)
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- patch_size = to_2tuple(patch_size)
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- patches_resolution = [
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- pretrain_img_size[0] // patch_size[0],
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- pretrain_img_size[1] // patch_size[1]
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- ]
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-
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- self.absolute_pos_embed = add_parameter(
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- self,
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- paddle.zeros((1, embed_dim, patches_resolution[0],
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- patches_resolution[1])))
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- trunc_normal_(self.absolute_pos_embed)
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-
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- self.pos_drop = nn.Dropout(p=drop_rate)
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-
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- # stochastic depth
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- dpr = np.linspace(0, drop_path_rate,
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- sum(depths)) # stochastic depth decay rule
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-
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- # build layers
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- self.layers = nn.LayerList()
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- for i_layer in range(self.num_layers):
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- layer = BasicLayer(
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- dim=int(embed_dim * 2**i_layer),
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- depth=depths[i_layer],
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- num_heads=num_heads[i_layer],
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- window_size=window_size,
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- mlp_ratio=mlp_ratio,
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- qkv_bias=qkv_bias,
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- qk_scale=qk_scale,
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- drop=drop_rate,
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- attn_drop=attn_drop_rate,
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- drop_path=dpr[sum(depths[:i_layer]):sum(depths[:i_layer + 1])],
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- norm_layer=norm_layer,
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- downsample=PatchMerging
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- if (i_layer < self.num_layers - 1) else None)
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- self.layers.append(layer)
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-
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- num_features = [int(embed_dim * 2**i) for i in range(self.num_layers)]
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- self.num_features = num_features
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-
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- # add a norm layer for each output
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- for i_layer in out_indices:
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- layer = norm_layer(num_features[i_layer])
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- layer_name = f'norm{i_layer}'
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- self.add_sublayer(layer_name, layer)
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-
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- self.apply(self._init_weights)
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- self._freeze_stages()
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- if pretrained:
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- if 'http' in pretrained: #URL
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- path = paddle.utils.download.get_weights_path_from_url(
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- pretrained)
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- else: #model in local path
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- path = pretrained
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- self.set_state_dict(paddle.load(path))
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-
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- def _freeze_stages(self):
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- if self.frozen_stages >= 0:
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- self.patch_embed.eval()
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- for param in self.patch_embed.parameters():
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- param.requires_grad = False
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-
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- if self.frozen_stages >= 1 and self.ape:
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- self.absolute_pos_embed.requires_grad = False
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-
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- if self.frozen_stages >= 2:
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- self.pos_drop.eval()
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- for i in range(0, self.frozen_stages - 1):
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- m = self.layers[i]
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- m.eval()
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- for param in m.parameters():
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- param.requires_grad = False
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-
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- def _init_weights(self, m):
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- if isinstance(m, nn.Linear):
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- trunc_normal_(m.weight)
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- if isinstance(m, nn.Linear) and m.bias is not None:
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- zeros_(m.bias)
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- elif isinstance(m, nn.LayerNorm):
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- zeros_(m.bias)
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- ones_(m.weight)
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-
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- def forward(self, x):
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- """Forward function."""
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- x = self.patch_embed(x['image'])
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- _, _, Wh, Ww = x.shape
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- if self.ape:
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- # interpolate the position embedding to the corresponding size
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- absolute_pos_embed = F.interpolate(
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- self.absolute_pos_embed, size=(Wh, Ww), mode='bicubic')
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- x = (x + absolute_pos_embed).flatten(2).transpose([0, 2, 1])
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- else:
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- x = x.flatten(2).transpose([0, 2, 1])
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- x = self.pos_drop(x)
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- outs = []
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- for i in range(self.num_layers):
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- layer = self.layers[i]
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- x_out, H, W, x, Wh, Ww = layer(x, Wh, Ww)
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- if i in self.out_indices:
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- norm_layer = getattr(self, f'norm{i}')
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- x_out = norm_layer(x_out)
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- out = x_out.reshape(
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- (-1, H, W, self.num_features[i])).transpose((0, 3, 1, 2))
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- outs.append(out)
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-
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- return tuple(outs)
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-
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- @property
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- def out_shape(self):
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- out_strides = [4, 8, 16, 32]
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- return [
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- ShapeSpec(
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- channels=self.num_features[i], stride=out_strides[i])
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- for i in self.out_indices
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- ]
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