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import torch |
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from torch import nn, einsum |
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import torch.nn.functional as F |
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from einops import rearrange, repeat |
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from einops.layers.torch import Rearrange |
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class Residual(nn.Module): |
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def __init__(self, fn): |
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super().__init__() |
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self.fn = fn |
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def forward(self, x, **kwargs): |
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return self.fn(x, **kwargs) + x |
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class SA_PreNorm(nn.Module): |
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def __init__(self, dim, fn): |
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super().__init__() |
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self.norm = nn.LayerNorm(dim) |
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self.fn = fn |
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def forward(self, x, **kwargs): |
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return self.fn(self.norm(x), **kwargs) |
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class SA_FeedForward(nn.Module): |
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def __init__(self, dim, hidden_dim, dropout = 0.): |
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super().__init__() |
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self.net = nn.Sequential( |
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nn.Linear(dim, hidden_dim), |
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nn.GELU(), |
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nn.Dropout(dropout), |
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nn.Linear(hidden_dim, dim), |
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nn.Dropout(dropout) |
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) |
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def forward(self, x): |
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return self.net(x) |
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class SA_Attention(nn.Module): |
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def __init__(self, dim, heads = 8, dim_head = 64, dropout = 0.): |
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super().__init__() |
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inner_dim = dim_head * heads |
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project_out = not (heads == 1 and dim_head == dim) |
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self.heads = heads |
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self.scale = dim_head ** -0.5 |
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self.to_qkv = nn.Linear(dim, inner_dim * 3, bias = False) |
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self.to_out = nn.Sequential( |
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nn.Linear(inner_dim, dim), |
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nn.Dropout(dropout) |
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) if project_out else nn.Identity() |
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def forward(self, x): |
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b, n, _, h = *x.shape, self.heads |
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qkv = self.to_qkv(x).chunk(3, dim = -1) |
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q, k, v = map(lambda t: rearrange(t, 'b n (h d) -> b h n d', h = h), qkv) |
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dots = einsum('b h i d, b h j d -> b h i j', q, k) * self.scale |
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attn = dots.softmax(dim=-1) |
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out = einsum('b h i j, b h j d -> b h i d', attn, v) |
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out = rearrange(out, 'b h n d -> b n (h d)') |
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out = self.to_out(out) |
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return out |
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class ReAttention(nn.Module): |
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def __init__(self, dim, heads = 8, dim_head = 64, dropout = 0.): |
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super().__init__() |
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inner_dim = dim_head * heads |
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self.heads = heads |
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self.scale = dim_head ** -0.5 |
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self.to_qkv = nn.Linear(dim, inner_dim * 3, bias = False) |
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self.reattn_weights = nn.Parameter(torch.randn(heads, heads)) |
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self.reattn_norm = nn.Sequential( |
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Rearrange('b h i j -> b i j h'), |
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nn.LayerNorm(heads), |
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Rearrange('b i j h -> b h i j') |
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) |
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self.to_out = nn.Sequential( |
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nn.Linear(inner_dim, dim), |
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nn.Dropout(dropout) |
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) |
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def forward(self, x): |
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b, n, _, h = *x.shape, self.heads |
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qkv = self.to_qkv(x).chunk(3, dim = -1) |
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q, k, v = map(lambda t: rearrange(t, 'b n (h d) -> b h n d', h = h), qkv) |
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dots = einsum('b h i d, b h j d -> b h i j', q, k) * self.scale |
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attn = dots.softmax(dim=-1) |
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attn = einsum('b h i j, h g -> b g i j', attn, self.reattn_weights) |
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attn = self.reattn_norm(attn) |
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out = einsum('b h i j, b h j d -> b h i d', attn, v) |
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out = rearrange(out, 'b h n d -> b n (h d)') |
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out = self.to_out(out) |
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return out |
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class LeFF(nn.Module): |
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def __init__(self, dim = 192, scale = 4, depth_kernel = 3): |
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super().__init__() |
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scale_dim = dim*scale |
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self.up_proj = nn.Sequential(nn.Linear(dim, scale_dim), |
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Rearrange('b n c -> b c n'), |
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nn.BatchNorm1d(scale_dim), |
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nn.GELU(), |
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Rearrange('b c (h w) -> b c h w', h=14, w=14) |
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) |
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self.depth_conv = nn.Sequential(nn.Conv2d(scale_dim, scale_dim, kernel_size=depth_kernel, padding=1, groups=scale_dim, bias=False), |
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nn.BatchNorm2d(scale_dim), |
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nn.GELU(), |
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Rearrange('b c h w -> b (h w) c', h=14, w=14) |
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) |
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self.down_proj = nn.Sequential(nn.Linear(scale_dim, dim), |
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Rearrange('b n c -> b c n'), |
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nn.BatchNorm1d(dim), |
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nn.GELU(), |
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Rearrange('b c n -> b n c') |
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) |
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def forward(self, x): |
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x = self.up_proj(x) |
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x = self.depth_conv(x) |
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x = self.down_proj(x) |
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return x |
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class LCAttention(nn.Module): |
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def __init__(self, dim, heads = 8, dim_head = 64, dropout = 0.): |
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super().__init__() |
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inner_dim = dim_head * heads |
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project_out = not (heads == 1 and dim_head == dim) |
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self.heads = heads |
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self.scale = dim_head ** -0.5 |
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self.to_qkv = nn.Linear(dim, inner_dim * 3, bias = False) |
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self.to_out = nn.Sequential( |
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nn.Linear(inner_dim, dim), |
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nn.Dropout(dropout) |
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) if project_out else nn.Identity() |
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def forward(self, x): |
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b, n, _, h = *x.shape, self.heads |
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qkv = self.to_qkv(x).chunk(3, dim = -1) |
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q, k, v = map(lambda t: rearrange(t, 'b n (h d) -> b h n d', h = h), qkv) |
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q = q[:, :, -1, :].unsqueeze(2) |
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dots = einsum('b h i d, b h j d -> b h i j', q, k) * self.scale |
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attn = dots.softmax(dim=-1) |
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out = einsum('b h i j, b h j d -> b h i d', attn, v) |
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out = rearrange(out, 'b h n d -> b n (h d)') |
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out = self.to_out(out) |
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return out |
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class SA_Transformer(nn.Module): |
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def __init__(self, dim, depth, heads, dim_head, mlp_dim, dropout = 0.): |
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super().__init__() |
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self.layers = nn.ModuleList([]) |
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self.norm = nn.LayerNorm(dim) |
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for _ in range(depth): |
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self.layers.append(nn.ModuleList([ |
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SA_PreNorm(dim, SA_Attention(dim, heads = heads, dim_head = dim_head, dropout = dropout)), |
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SA_PreNorm(dim, SA_FeedForward(dim, mlp_dim, dropout = dropout)) |
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])) |
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def forward(self, x): |
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for attn, ff in self.layers: |
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x = attn(x) + x |
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x = ff(x) + x |
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return self.norm(x) |
