693 lines
29 KiB
Python
693 lines
29 KiB
Python
# --------------------------------------------------------
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# Swin Transformer V2
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# Copyright (c) 2022 Microsoft
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# Licensed under The MIT License [see LICENSE for details]
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# Written by Ze Liu
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# --------------------------------------------------------
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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import torch.utils.checkpoint as checkpoint
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from timm.layers import DropPath, to_2tuple, trunc_normal_
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import numpy as np
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import math
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class Mlp(nn.Module):
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def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, 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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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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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.view(B, H // window_size, window_size, W // window_size, window_size, C)
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windows = x.permute(0, 1, 3, 2, 4, 5).contiguous().view(-1, window_size, window_size, C)
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return windows
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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.view(B, H // window_size, W // window_size, window_size, window_size, -1)
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x = x.permute(0, 1, 3, 2, 4, 5).contiguous().view(B, H, W, -1)
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return x
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class WindowAttention(nn.Module):
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r""" 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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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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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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pretrained_window_size (tuple[int]): The height and width of the window in pre-training.
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"""
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def __init__(self, dim, window_size, num_heads, qkv_bias=True, attn_drop=0., proj_drop=0.,
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pretrained_window_size=[0, 0]):
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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.pretrained_window_size = pretrained_window_size
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self.num_heads = num_heads
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self.logit_scale = nn.Parameter(torch.log(10 * torch.ones((num_heads, 1, 1))), requires_grad=True)
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# mlp to generate continuous relative position bias
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self.cpb_mlp = nn.Sequential(nn.Linear(2, 512, bias=True),
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nn.ReLU(inplace=True),
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nn.Linear(512, num_heads, bias=False))
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# get relative_coords_table
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relative_coords_h = torch.arange(-(self.window_size[0] - 1), self.window_size[0], dtype=torch.float32)
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relative_coords_w = torch.arange(-(self.window_size[1] - 1), self.window_size[1], dtype=torch.float32)
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relative_coords_table = torch.stack(
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torch.meshgrid([relative_coords_h,
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relative_coords_w], indexing='ij')).permute(1, 2, 0).contiguous().unsqueeze(0) # 1, 2*Wh-1, 2*Ww-1, 2
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if pretrained_window_size[0] > 0:
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relative_coords_table[:, :, :, 0] /= (pretrained_window_size[0] - 1)
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relative_coords_table[:, :, :, 1] /= (pretrained_window_size[1] - 1)
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else:
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relative_coords_table[:, :, :, 0] /= (self.window_size[0] - 1)
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relative_coords_table[:, :, :, 1] /= (self.window_size[1] - 1)
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relative_coords_table *= 8 # normalize to -8, 8
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relative_coords_table = torch.sign(relative_coords_table) * torch.log2(
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torch.abs(relative_coords_table) + 1.0) / np.log2(8)
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self.register_buffer("relative_coords_table", relative_coords_table)
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# get pair-wise relative position index for each token inside the window
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coords_h = torch.arange(self.window_size[0])
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coords_w = torch.arange(self.window_size[1])
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coords = torch.stack(torch.meshgrid([coords_h, coords_w], indexing='ij')) # 2, Wh, Ww
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coords_flatten = torch.flatten(coords, 1) # 2, Wh*Ww
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relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :] # 2, Wh*Ww, Wh*Ww
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relative_coords = relative_coords.permute(1, 2, 0).contiguous() # Wh*Ww, Wh*Ww, 2
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relative_coords[:, :, 0] += self.window_size[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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relative_position_index = relative_coords.sum(-1) # Wh*Ww, Wh*Ww
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self.register_buffer("relative_position_index", relative_position_index)
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self.qkv = nn.Linear(dim, dim * 3, bias=False)
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if qkv_bias:
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self.q_bias = nn.Parameter(torch.zeros(dim))
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self.v_bias = nn.Parameter(torch.zeros(dim))
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else:
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self.q_bias = None
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self.v_bias = None
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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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self.softmax = nn.Softmax(dim=-1)
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def forward(self, x, mask=None):
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"""
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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_bias = None
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if self.q_bias is not None:
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qkv_bias = torch.cat((self.q_bias, torch.zeros_like(self.v_bias, requires_grad=False), self.v_bias))
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qkv = F.linear(input=x, weight=self.qkv.weight, bias=qkv_bias)
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qkv = qkv.reshape(B_, N, 3, self.num_heads, -1).permute(2, 0, 3, 1, 4)
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q, k, v = qkv[0], qkv[1], qkv[2] # make torchscript happy (cannot use tensor as tuple)
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# cosine attention
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attn = (F.normalize(q, dim=-1) @ F.normalize(k, dim=-1).transpose(-2, -1))
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max_val = math.log(1. / 0.01)
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logit_scale = torch.clamp(self.logit_scale, max=max_val).exp()
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attn = attn * logit_scale
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relative_position_bias_table = self.cpb_mlp(self.relative_coords_table).view(-1, self.num_heads)
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relative_position_bias = relative_position_bias_table[self.relative_position_index.view(-1)].view(
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self.window_size[0] * self.window_size[1], self.window_size[0] * self.window_size[1], -1) # Wh*Ww,Wh*Ww,nH
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relative_position_bias = relative_position_bias.permute(2, 0, 1).contiguous() # nH, Wh*Ww, Wh*Ww
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relative_position_bias = 16 * torch.sigmoid(relative_position_bias)
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attn = attn + relative_position_bias.unsqueeze(0)
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if mask is not None:
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nW = mask.shape[0]
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attn = attn.view(B_ // nW, nW, self.num_heads, N, N) + mask.unsqueeze(1).unsqueeze(0)
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attn = attn.view(-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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attn = self.attn_drop(attn)
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x = (attn @ v).transpose(1, 2).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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def extra_repr(self) -> str:
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return f'dim={self.dim}, window_size={self.window_size}, ' \
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f'pretrained_window_size={self.pretrained_window_size}, num_heads={self.num_heads}'
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def flops(self, N):
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# calculate flops for 1 window with token length of N
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flops = 0
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# qkv = self.qkv(x)
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flops += N * self.dim * 3 * self.dim
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# attn = (q @ k.transpose(-2, -1))
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flops += self.num_heads * N * (self.dim // self.num_heads) * N
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# x = (attn @ v)
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flops += self.num_heads * N * N * (self.dim // self.num_heads)
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# x = self.proj(x)
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flops += N * self.dim * self.dim
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return flops
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class SwinTransformerBlock(nn.Module):
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r""" Swin Transformer Block.
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Args:
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dim (int): Number of input channels.
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input_resolution (tuple[int]): Input resulotion.
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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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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.Module, optional): Activation layer. Default: nn.GELU
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norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
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pretrained_window_size (int): Window size in pre-training.
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"""
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def __init__(self, dim, input_resolution, num_heads, window_size=7, shift_size=0,
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mlp_ratio=4., qkv_bias=True, drop=0., attn_drop=0., drop_path=0.,
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act_layer=nn.GELU, norm_layer=nn.LayerNorm, pretrained_window_size=0):
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super().__init__()
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self.dim = dim
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self.input_resolution = input_resolution
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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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if min(self.input_resolution) <= self.window_size:
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# if window size is larger than input resolution, we don't partition windows
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self.shift_size = 0
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self.window_size = min(self.input_resolution)
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assert 0 <= self.shift_size < self.window_size, "shift_size must in 0-window_size"
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self.norm1 = norm_layer(dim)
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self.attn = WindowAttention(
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dim, window_size=to_2tuple(self.window_size), num_heads=num_heads,
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qkv_bias=qkv_bias, attn_drop=attn_drop, proj_drop=drop,
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pretrained_window_size=to_2tuple(pretrained_window_size))
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self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.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, hidden_features=mlp_hidden_dim, act_layer=act_layer, drop=drop)
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if self.shift_size > 0:
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# calculate attention mask for SW-MSA
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H, W = self.input_resolution
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img_mask = torch.zeros((1, H, W, 1)) # 1 H W 1
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h_slices = (slice(0, -self.window_size),
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slice(-self.window_size, -self.shift_size),
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slice(-self.shift_size, None))
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w_slices = (slice(0, -self.window_size),
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slice(-self.window_size, -self.shift_size),
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slice(-self.shift_size, None))
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cnt = 0
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for h in h_slices:
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for w in w_slices:
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img_mask[:, h, w, :] = cnt
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cnt += 1
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mask_windows = window_partition(img_mask, self.window_size) # nW, window_size, window_size, 1
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mask_windows = mask_windows.view(-1, self.window_size * self.window_size)
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attn_mask = mask_windows.unsqueeze(1) - mask_windows.unsqueeze(2)
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attn_mask = attn_mask.masked_fill(attn_mask != 0, float(-100.0)).masked_fill(attn_mask == 0, float(0.0))
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else:
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attn_mask = None
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self.register_buffer("attn_mask", attn_mask)
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def forward(self, x):
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H, W = self.input_resolution
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B, L, C = x.shape
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assert L == H * W, "input feature has wrong size"
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shortcut = x
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x = x.view(B, H, W, C)
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# cyclic shift
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if self.shift_size > 0:
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shifted_x = torch.roll(x, shifts=(-self.shift_size, -self.shift_size), dims=(1, 2))
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else:
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shifted_x = x
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# partition windows
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x_windows = window_partition(shifted_x, self.window_size) # nW*B, window_size, window_size, C
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x_windows = x_windows.view(-1, self.window_size * self.window_size, C) # nW*B, window_size*window_size, C
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# W-MSA/SW-MSA
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attn_windows = self.attn(x_windows, mask=self.attn_mask) # nW*B, window_size*window_size, C
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# merge windows
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attn_windows = attn_windows.view(-1, self.window_size, self.window_size, C)
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shifted_x = window_reverse(attn_windows, self.window_size, H, W) # B H' W' C
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# reverse cyclic shift
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if self.shift_size > 0:
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x = torch.roll(shifted_x, shifts=(self.shift_size, self.shift_size), dims=(1, 2))
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else:
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x = shifted_x
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x = x.view(B, H * W, C)
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x = shortcut + self.drop_path(self.norm1(x))
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# FFN
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x = x + self.drop_path(self.norm2(self.mlp(x)))
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return x
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def extra_repr(self) -> str:
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return f"dim={self.dim}, input_resolution={self.input_resolution}, num_heads={self.num_heads}, " \
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f"window_size={self.window_size}, shift_size={self.shift_size}, mlp_ratio={self.mlp_ratio}"
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def flops(self):
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flops = 0
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H, W = self.input_resolution
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# norm1
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flops += self.dim * H * W
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# W-MSA/SW-MSA
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nW = H * W / self.window_size / self.window_size
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flops += nW * self.attn.flops(self.window_size * self.window_size)
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# mlp
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flops += 2 * H * W * self.dim * self.dim * self.mlp_ratio
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# norm2
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flops += self.dim * H * W
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return flops
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class PatchMerging(nn.Module):
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r""" Patch Merging Layer.
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Args:
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input_resolution (tuple[int]): Resolution of input feature.
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dim (int): Number of input channels.
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norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
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"""
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def __init__(self, input_resolution, dim, norm_layer=nn.LayerNorm):
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super().__init__()
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self.input_resolution = input_resolution
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self.dim = dim
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self.reduction = nn.Linear(4 * dim, 2 * dim, bias=False)
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self.norm = norm_layer(2 * dim)
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def forward(self, x):
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"""
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x: B, H*W, C
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"""
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H, W = self.input_resolution
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B, L, C = x.shape
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assert L == H * W, "input feature has wrong size"
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assert H % 2 == 0 and W % 2 == 0, f"x size ({H}*{W}) are not even."
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x = x.view(B, H, W, C)
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x0 = x[:, 0::2, 0::2, :] # B H/2 W/2 C
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x1 = x[:, 1::2, 0::2, :] # B H/2 W/2 C
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x2 = x[:, 0::2, 1::2, :] # B H/2 W/2 C
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x3 = x[:, 1::2, 1::2, :] # B H/2 W/2 C
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x = torch.cat([x0, x1, x2, x3], -1) # B H/2 W/2 4*C
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x = x.view(B, -1, 4 * C) # B H/2*W/2 4*C
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x = self.reduction(x)
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x = self.norm(x)
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return x
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def extra_repr(self) -> str:
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return f"input_resolution={self.input_resolution}, dim={self.dim}"
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def flops(self):
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H, W = self.input_resolution
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flops = (H // 2) * (W // 2) * 4 * self.dim * 2 * self.dim
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flops += H * W * self.dim // 2
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return flops
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class BasicLayer(nn.Module):
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""" A basic Swin Transformer layer for one stage.
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Args:
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dim (int): Number of input channels.
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input_resolution (tuple[int]): Input resolution.
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depth (int): Number of blocks.
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num_heads (int): Number of attention heads.
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window_size (int): Local window size.
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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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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 | tuple[float], optional): Stochastic depth rate. Default: 0.0
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norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
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downsample (nn.Module | None, optional): Downsample layer at the end of the layer. Default: None
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use_checkpoint (bool): Whether to use checkpointing to save memory. Default: False.
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pretrained_window_size (int): Local window size in pre-training.
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"""
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def __init__(self, dim, input_resolution, depth, num_heads, window_size,
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mlp_ratio=4., qkv_bias=True, drop=0., attn_drop=0.,
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drop_path=0., norm_layer=nn.LayerNorm, downsample=None, use_checkpoint=False,
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pretrained_window_size=0):
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super().__init__()
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self.dim = dim
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self.input_resolution = input_resolution
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self.depth = depth
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self.use_checkpoint = use_checkpoint
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# build blocks
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|
self.blocks = nn.ModuleList([
|
|
SwinTransformerBlock(dim=dim, input_resolution=input_resolution,
|
|
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,
|
|
drop=drop, attn_drop=attn_drop,
|
|
drop_path=drop_path[i] if isinstance(drop_path, list) else drop_path,
|
|
norm_layer=norm_layer,
|
|
pretrained_window_size=pretrained_window_size)
|
|
for i in range(depth)])
|
|
|
|
# patch merging layer
|
|
if downsample is not None:
|
|
self.downsample = downsample(input_resolution, dim=dim, norm_layer=norm_layer)
|
|
else:
|
|
self.downsample = None
|
|
|
|
def forward(self, x):
|
|
for blk in self.blocks:
|
|
if self.use_checkpoint:
|
|
x = checkpoint.checkpoint(blk, x)
|
|
else:
|
|
x = blk(x)
|
|
if self.downsample is not None:
|
|
x = self.downsample(x)
|
|
return x
|
|
|
|
def extra_repr(self) -> str:
|
|
return f"dim={self.dim}, input_resolution={self.input_resolution}, depth={self.depth}"
|
|
|
|
def flops(self):
|
|
flops = 0
|
|
for blk in self.blocks:
|
|
flops += blk.flops()
|
|
if self.downsample is not None:
|
|
flops += self.downsample.flops()
|
|
return flops
|
|
|
|
def _init_respostnorm(self):
|
|
for blk in self.blocks:
|
|
nn.init.constant_(blk.norm1.bias, 0)
|
|
nn.init.constant_(blk.norm1.weight, 0)
|
|
nn.init.constant_(blk.norm2.bias, 0)
|
|
nn.init.constant_(blk.norm2.weight, 0)
|
|
|
|
|
|
class PatchEmbed(nn.Module):
|
|
r""" Image to Patch Embedding
|
|
|
|
Args:
|
|
img_size (int): Image size. Default: 224.
|
|
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.Module, optional): Normalization layer. Default: None
|
|
"""
|
|
|
|
def __init__(self, img_size=224, patch_size=4, in_chans=3, embed_dim=96, norm_layer=None):
|
|
super().__init__()
|
|
img_size = to_2tuple(img_size)
|
|
patch_size = to_2tuple(patch_size)
|
|
patches_resolution = [img_size[0] // patch_size[0], img_size[1] // patch_size[1]]
|
|
self.img_size = img_size
|
|
self.patch_size = patch_size
|
|
self.patches_resolution = patches_resolution
|
|
self.num_patches = patches_resolution[0] * patches_resolution[1]
|
|
|
|
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
|
|
# FIXME look at relaxing size constraints
|
|
assert H == self.img_size[0] and W == self.img_size[1], \
|
|
f"Input image size ({H}*{W}) doesn't match model ({self.img_size[0]}*{self.img_size[1]})."
|
|
x = self.proj(x).flatten(2).transpose(1, 2) # B Ph*Pw C
|
|
if self.norm is not None:
|
|
x = self.norm(x)
|
|
return x
|
|
|
|
def flops(self):
|
|
Ho, Wo = self.patches_resolution
|
|
flops = Ho * Wo * self.embed_dim * self.in_chans * (self.patch_size[0] * self.patch_size[1])
|
|
if self.norm is not None:
|
|
flops += Ho * Wo * self.embed_dim
|
|
return flops
|
|
|
|
|
|
class SwinTransformerV2(nn.Module):
|
|
r""" Swin Transformer
|
|
A PyTorch 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
|
|
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.Module): 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
|
|
use_checkpoint (bool): Whether to use checkpointing to save memory. Default: False
|
|
pretrained_window_sizes (tuple(int)): Pretrained window sizes of each layer.
|
|
"""
|
|
|
|
def __init__(self, img_size=224, patch_size=4, in_chans=3, num_classes=1000,
|
|
embed_dim=96, depths=[2, 2, 6, 2], num_heads=[3, 6, 12, 24],
|
|
window_size=7, mlp_ratio=4., qkv_bias=True,
|
|
drop_rate=0., attn_drop_rate=0., drop_path_rate=0.1,
|
|
norm_layer=nn.LayerNorm, ape=False, patch_norm=True,
|
|
use_checkpoint=False, pretrained_window_sizes=[0, 0, 0, 0], **kwargs):
|
|
super().__init__()
|
|
|
|
self.num_classes = num_classes
|
|
self.num_layers = len(depths)
|
|
self.embed_dim = embed_dim
|
|
self.ape = ape
|
|
self.patch_norm = patch_norm
|
|
self.num_features = int(embed_dim * 2 ** (self.num_layers - 1))
|
|
self.mlp_ratio = mlp_ratio
|
|
|
|
# split image into non-overlapping patches
|
|
self.patch_embed = PatchEmbed(
|
|
img_size=img_size, patch_size=patch_size, in_chans=in_chans, embed_dim=embed_dim,
|
|
norm_layer=norm_layer if self.patch_norm else None)
|
|
num_patches = self.patch_embed.num_patches
|
|
patches_resolution = self.patch_embed.patches_resolution
|
|
self.patches_resolution = patches_resolution
|
|
|
|
# absolute position embedding
|
|
if self.ape:
|
|
self.absolute_pos_embed = nn.Parameter(torch.zeros(1, num_patches, embed_dim))
|
|
trunc_normal_(self.absolute_pos_embed, std=.02)
|
|
|
|
self.pos_drop = nn.Dropout(p=drop_rate)
|
|
|
|
# stochastic depth
|
|
dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))] # stochastic depth decay rule
|
|
|
|
# build layers
|
|
self.layers = nn.ModuleList()
|
|
for i_layer in range(self.num_layers):
|
|
layer = BasicLayer(dim=int(embed_dim * 2 ** i_layer),
|
|
input_resolution=(patches_resolution[0] // (2 ** i_layer),
|
|
patches_resolution[1] // (2 ** i_layer)),
|
|
depth=depths[i_layer],
|
|
num_heads=num_heads[i_layer],
|
|
window_size=window_size,
|
|
mlp_ratio=self.mlp_ratio,
|
|
qkv_bias=qkv_bias,
|
|
drop=drop_rate, attn_drop=attn_drop_rate,
|
|
drop_path=dpr[sum(depths[:i_layer]):sum(depths[:i_layer + 1])],
|
|
norm_layer=norm_layer,
|
|
downsample=PatchMerging if (i_layer < self.num_layers - 1) else None,
|
|
use_checkpoint=use_checkpoint,
|
|
pretrained_window_size=pretrained_window_sizes[i_layer])
|
|
self.layers.append(layer)
|
|
|
|
self.norm = norm_layer(self.num_features)
|
|
self.avgpool = nn.AdaptiveAvgPool1d(1)
|
|
self.head = nn.Linear(self.num_features, num_classes) if num_classes > 0 else nn.Identity()
|
|
|
|
self.apply(self._init_weights)
|
|
for bly in self.layers:
|
|
bly._init_respostnorm()
|
|
|
|
def _init_weights(self, m):
|
|
if isinstance(m, nn.Linear):
|
|
trunc_normal_(m.weight, std=.02)
|
|
if isinstance(m, nn.Linear) and m.bias is not None:
|
|
nn.init.constant_(m.bias, 0)
|
|
elif isinstance(m, nn.LayerNorm):
|
|
nn.init.constant_(m.bias, 0)
|
|
nn.init.constant_(m.weight, 1.0)
|
|
|
|
@torch.jit.ignore
|
|
def no_weight_decay(self):
|
|
return {'absolute_pos_embed'}
|
|
|
|
@torch.jit.ignore
|
|
def no_weight_decay_keywords(self):
|
|
return {"cpb_mlp", "logit_scale", 'relative_position_bias_table'}
|
|
|
|
def forward_features(self, x):
|
|
x = self.patch_embed(x)
|
|
if self.ape:
|
|
x = x + self.absolute_pos_embed
|
|
x = self.pos_drop(x)
|
|
|
|
for layer in self.layers:
|
|
x = layer(x)
|
|
|
|
x = self.norm(x) # B L C
|
|
x = self.avgpool(x.transpose(1, 2)) # B C 1
|
|
x = torch.flatten(x, 1)
|
|
return x
|
|
|
|
def forward(self, x):
|
|
x = self.forward_features(x)
|
|
x = self.head(x)
|
|
return x
|
|
|
|
def flops(self):
|
|
flops = 0
|
|
flops += self.patch_embed.flops()
|
|
for i, layer in enumerate(self.layers):
|
|
flops += layer.flops()
|
|
flops += self.num_features * self.patches_resolution[0] * self.patches_resolution[1] // (2 ** self.num_layers)
|
|
flops += self.num_features * self.num_classes
|
|
return flops
|
|
|
|
|
|
# class STB(nn.Module):
|
|
# """Defines the Swin transformer block (STB)."""
|
|
#
|
|
# def __init__(self, dim, input_resolution, num_heads=3, window_size=4,
|
|
# mlp_ratio=4., qkv_bias=True, drop=0., attn_drop=0.,
|
|
# drop_path=0., norm_layer=nn.LayerNorm, downsample=None, use_checkpoint=False,
|
|
# pretrained_window_size=0):
|
|
# """Initialize the STB instance with specified parameters."""
|
|
# super(STB, self).__init__()
|
|
# self.SwinTransformerBlock = SwinTransformerBlock(dim=dim, input_resolution=input_resolution,
|
|
# num_heads=num_heads, window_size=window_size,
|
|
# shift_size=window_size // 2,
|
|
# mlp_ratio=mlp_ratio,
|
|
# qkv_bias=qkv_bias,
|
|
# drop=drop, attn_drop=attn_drop,
|
|
# drop_path=drop_path,
|
|
# norm_layer=norm_layer,
|
|
# pretrained_window_size=pretrained_window_size)
|
|
#
|
|
# def forward(self, x):
|
|
# """Forward pass for the AIFI transformer layer."""
|
|
# B, C, H, W = x.shape
|
|
# x = x.view(B, C, H * W).permute(0, 2, 1)
|
|
# x = self.SwinTransformerBlock(x)
|
|
# x = x.view(B, H, W, C).permute(0, 3, 1, 2)
|
|
# return x
|
|
|
|
class STB(nn.Module):
|
|
"""Defines the Swin transformer block (STB)."""
|
|
|
|
def __init__(self, dim, input_resolution, num_heads=3, depth=4, window_size=4,
|
|
mlp_ratio=4., qkv_bias=True, drop=0., attn_drop=0.,
|
|
drop_path=0., norm_layer=nn.LayerNorm, downsample=None, use_checkpoint=False,
|
|
pretrained_window_size=0, drop_path_rate=0.1):
|
|
"""Initialize the STB instance with specified parameters."""
|
|
super(STB, self).__init__()
|
|
drop_path = [x.item() for x in torch.linspace(0, drop_path_rate, depth)]
|
|
self.SwinTransformerBlock = nn.ModuleList([
|
|
SwinTransformerBlock(dim=dim, input_resolution=input_resolution,
|
|
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,
|
|
drop=drop, attn_drop=attn_drop,
|
|
drop_path=drop_path[i] if isinstance(drop_path, list) else drop_path,
|
|
norm_layer=norm_layer,
|
|
pretrained_window_size=pretrained_window_size)
|
|
for i in range(depth)])
|
|
|
|
def forward(self, x):
|
|
"""Forward pass for the AIFI transformer layer."""
|
|
B, C, H, W = x.shape
|
|
x = x.view(B, C, H * W).permute(0, 2, 1)
|
|
for blk in self.SwinTransformerBlock:
|
|
x = blk(x)
|
|
x = x.view(B, H, W, C).permute(0, 3, 1, 2)
|
|
return x |