Rename and add flash atten

6 files changed, 218 insertions, 0 deletions

diff --git a/text_recognizer/network/convnext/__init__.py b/text_recognizer/network/convnext/__init__.py
new file mode 100644
index 0000000..dcff3fc
--- /dev/null
+++ b/text_recognizer/network/convnext/__init__.py
@@ -0,0 +1,7 @@
+"""Convnext module."""
+from text_recognizer.network.convnext.attention import (
+    Attention,
+    FeedForward,
+    TransformerBlock,
+)
+from text_recognizer.network.convnext.convnext import ConvNext
diff --git a/text_recognizer/network/convnext/attention.py b/text_recognizer/network/convnext/attention.py
new file mode 100644
index 0000000..6bc9692
--- /dev/null
+++ b/text_recognizer/network/convnext/attention.py
@@ -0,0 +1,79 @@
+"""Convolution self attention block."""
+
+import torch.nn.functional as F
+from einops import rearrange
+from torch import Tensor, einsum, nn
+
+from text_recognizer.network.convnext.norm import LayerNorm
+from text_recognizer.network.convnext.residual import Residual
+
+
+def l2norm(t: Tensor) -> Tensor:
+    return F.normalize(t, dim=-1)
+
+
+class FeedForward(nn.Module):
+    def __init__(self, dim: int, mult: int = 4) -> None:
+        super().__init__()
+        inner_dim = int(dim * mult)
+        self.fn = Residual(
+            nn.Sequential(
+                LayerNorm(dim),
+                nn.Conv2d(dim, inner_dim, 1, bias=False),
+                nn.GELU(),
+                LayerNorm(inner_dim),
+                nn.Conv2d(inner_dim, dim, 1, bias=False),
+            )
+        )
+
+    def forward(self, x: Tensor) -> Tensor:
+        return self.fn(x)
+
+
+class Attention(nn.Module):
+    def __init__(
+        self, dim: int, heads: int = 4, dim_head: int = 64, scale: int = 8
+    ) -> None:
+        super().__init__()
+        self.scale = scale
+        self.heads = heads
+        inner_dim = heads * dim_head
+        self.norm = LayerNorm(dim)
+
+        self.to_qkv = nn.Conv2d(dim, inner_dim * 3, 1, bias=False)
+        self.to_out = nn.Conv2d(inner_dim, dim, 1, bias=False)
+
+    def forward(self, x: Tensor) -> Tensor:
+        h, w = x.shape[-2:]
+
+        residual = x.clone()
+
+        x = self.norm(x)
+
+        q, k, v = self.to_qkv(x).chunk(3, dim=1)
+        q, k, v = map(
+            lambda t: rearrange(t, "b (h c) ... -> b h (...) c", h=self.heads),
+            (q, k, v),
+        )
+
+        q, k = map(l2norm, (q, k))
+
+        sim = einsum("b h i d, b h j d -> b h i j", q, k) * self.scale
+        attn = sim.softmax(dim=-1)
+
+        out = einsum("b h i j, b h j d -> b h i d", attn, v)
+
+        out = rearrange(out, "b h (x y) d -> b (h d) x y", x=h, y=w)
+        return self.to_out(out) + residual
+
+
+class TransformerBlock(nn.Module):
+    def __init__(self, attn: Attention, ff: FeedForward) -> None:
+        super().__init__()
+        self.attn = attn
+        self.ff = ff
+
+    def forward(self, x: Tensor) -> Tensor:
+        x = self.attn(x)
+        x = self.ff(x)
+        return x
diff --git a/text_recognizer/network/convnext/convnext.py b/text_recognizer/network/convnext/convnext.py
new file mode 100644
index 0000000..6acf059
--- /dev/null
+++ b/text_recognizer/network/convnext/convnext.py
@@ -0,0 +1,77 @@
+"""ConvNext module."""
+from typing import Optional, Sequence
+
+from torch import Tensor, nn
+
+from text_recognizer.network.convnext.attention import TransformerBlock
+from text_recognizer.network.convnext.downsample import Downsample
+from text_recognizer.network.convnext.norm import LayerNorm
+
+
+class ConvNextBlock(nn.Module):
+    """ConvNext block."""
+
+    def __init__(self, dim: int, dim_out: int, mult: int) -> None:
+        super().__init__()
+        self.ds_conv = nn.Conv2d(
+            dim, dim, kernel_size=(7, 7), padding="same", groups=dim
+        )
+        self.net = nn.Sequential(
+            LayerNorm(dim),
+            nn.Conv2d(dim, dim_out * mult, kernel_size=(3, 3), padding="same"),
+            nn.GELU(),
+            nn.Conv2d(dim_out * mult, dim_out, kernel_size=(3, 3), padding="same"),
+        )
+        self.res_conv = nn.Conv2d(dim, dim_out, 1) if dim != dim_out else nn.Identity()
+
+    def forward(self, x: Tensor) -> Tensor:
+        h = self.ds_conv(x)
+        h = self.net(h)
+        return h + self.res_conv(x)
+
+
+class ConvNext(nn.Module):
+    def __init__(
+        self,
+        dim: int = 16,
+        dim_mults: Sequence[int] = (2, 4, 8),
+        depths: Sequence[int] = (3, 3, 6),
+        downsampling_factors: Sequence[Sequence[int]] = ((2, 2), (2, 2), (2, 2)),
+        attn: Optional[TransformerBlock] = None,
+    ) -> None:
+        super().__init__()
+        dims = (dim, *map(lambda m: m * dim, dim_mults))
+        self.attn = attn if attn is not None else nn.Identity()
+        self.out_channels = dims[-1]
+        self.stem = nn.Conv2d(1, dims[0], kernel_size=7, padding="same")
+        self.layers = nn.ModuleList([])
+
+        for i in range(len(dims) - 1):
+            dim_in, dim_out = dims[i], dims[i + 1]
+            self.layers.append(
+                nn.ModuleList(
+                    [
+                        ConvNextBlock(dim_in, dim_in, 2),
+                        nn.ModuleList(
+                            [ConvNextBlock(dim_in, dim_in, 2) for _ in range(depths[i])]
+                        ),
+                        Downsample(dim_in, dim_out, downsampling_factors[i]),
+                    ]
+                )
+            )
+        self.norm = LayerNorm(dims[-1])
+
+    def _init_weights(self, m):
+        if isinstance(m, (nn.Conv2d, nn.Linear)):
+            nn.init.trunc_normal_(m.weight, std=0.02)
+            nn.init.constant_(m.bias, 0)
+
+    def forward(self, x: Tensor) -> Tensor:
+        x = self.stem(x)
+        for init_block, blocks, down in self.layers:
+            x = init_block(x)
+            for fn in blocks:
+                x = fn(x)
+            x = down(x)
+        x = self.attn(x)
+        return self.norm(x)
diff --git a/text_recognizer/network/convnext/downsample.py b/text_recognizer/network/convnext/downsample.py
new file mode 100644
index 0000000..a8a0466
--- /dev/null
+++ b/text_recognizer/network/convnext/downsample.py
@@ -0,0 +1,21 @@
+"""Convnext downsample module."""
+from typing import Tuple
+
+from einops.layers.torch import Rearrange
+from torch import Tensor, nn
+
+
+class Downsample(nn.Module):
+    """Downsamples feature maps by patches."""
+
+    def __init__(self, dim: int, dim_out: int, factors: Tuple[int, int]) -> None:
+        super().__init__()
+        s1, s2 = factors
+        self.fn = nn.Sequential(
+            Rearrange("b c (h s1) (w s2) -> b (c s1 s2) h w", s1=s1, s2=s2),
+            nn.Conv2d(dim * s1 * s2, dim_out, 1),
+        )
+
+    def forward(self, x: Tensor) -> Tensor:
+        """Applies patch function."""
+        return self.fn(x)
diff --git a/text_recognizer/network/convnext/norm.py b/text_recognizer/network/convnext/norm.py
new file mode 100644
index 0000000..3355de9
--- /dev/null
+++ b/text_recognizer/network/convnext/norm.py
@@ -0,0 +1,18 @@
+"""Layer norm for conv layers."""
+import torch
+from torch import Tensor, nn
+
+
+class LayerNorm(nn.Module):
+    """Layer norm for convolutions."""
+
+    def __init__(self, dim: int) -> None:
+        super().__init__()
+        self.gamma = nn.Parameter(torch.ones(1, dim, 1, 1))
+
+    def forward(self, x: Tensor) -> Tensor:
+        """Applies layer norm."""
+        eps = 1e-5 if x.dtype == torch.float32 else 1e-3
+        var = torch.var(x, dim=1, unbiased=False, keepdim=True)
+        mean = torch.mean(x, dim=1, keepdim=True)
+        return (x - mean) / (var + eps).sqrt() * self.gamma
diff --git a/text_recognizer/network/convnext/residual.py b/text_recognizer/network/convnext/residual.py
new file mode 100644
index 0000000..dfc2847
--- /dev/null
+++ b/text_recognizer/network/convnext/residual.py
@@ -0,0 +1,16 @@
+"""Generic residual layer."""
+from typing import Callable
+
+from torch import Tensor, nn
+
+
+class Residual(nn.Module):
+    """Residual layer."""
+
+    def __init__(self, fn: Callable) -> None:
+        super().__init__()
+        self.fn = fn
+
+    def forward(self, x: Tensor) -> Tensor:
+        """Applies residual fn."""
+        return self.fn(x) + x