Add rotary embedding

1 files changed, 25 insertions, 0 deletions

diff --git a/text_recognizer/network/transformer/embedding/rotary.py b/text_recognizer/network/transformer/embedding/rotary.py
new file mode 100644
index 0000000..2254f81
--- /dev/null
+++ b/text_recognizer/network/transformer/embedding/rotary.py
@@ -0,0 +1,25 @@
+import torch
+from torch import nn, einsum
+from einops import rearrange
+
+
+class RotaryEmbedding(nn.Module):
+    def __init__(self, dim):
+        super().__init__()
+        inv_freq = 1.0 / (10000 ** (torch.arange(0, dim, 2).float() / dim))
+        self.register_buffer("inv_freq", inv_freq)
+
+    def forward(self, max_seq_len, *, device):
+        seq = torch.arange(max_seq_len, device=device, dtype=self.inv_freq.dtype)
+        freqs = einsum("i , j -> i j", seq, self.inv_freq)
+        return torch.cat((freqs, freqs), dim=-1)
+
+
+def rotate_half(x):
+    x = rearrange(x, "... (j d) -> ... j d", j=2)
+    x1, x2 = x.unbind(dim=-2)
+    return torch.cat((-x2, x1), dim=-1)
+
+
+def apply_rotary_pos_emb(pos, t):
+    return (t * pos.cos()) + (rotate_half(t) * pos.sin())