From 68cda1e6abf76312eb13f45ca3c8565a0b00d745 Mon Sep 17 00:00:00 2001
From: Gustaf Rydholm <gustaf.rydholm@gmail.com>
Date: Mon, 27 Jun 2022 18:17:16 +0200
Subject: Add quantizer

---
 text_recognizer/networks/quantizer/quantizer.py | 69 +++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 text_recognizer/networks/quantizer/quantizer.py

(limited to 'text_recognizer/networks/quantizer/quantizer.py')

diff --git a/text_recognizer/networks/quantizer/quantizer.py b/text_recognizer/networks/quantizer/quantizer.py
new file mode 100644
index 0000000..2c07b79
--- /dev/null
+++ b/text_recognizer/networks/quantizer/quantizer.py
@@ -0,0 +1,69 @@
+from typing import Optional, Tuple, Type
+
+from einops import rearrange
+import torch
+from torch import nn
+from torch import Tensor
+import torch.nn.functional as F
+
+from text_recognizer.networks.quantizer.utils import orthgonal_loss_fn
+
+
+class VectorQuantizer(nn.Module):
+    """Vector quantizer."""
+
+    def __init__(
+        self,
+        input_dim: int,
+        codebook: Type[nn.Module],
+        commitment: float = 1.0,
+        ort_reg_weight: float = 0,
+        ort_reg_max_codes: Optional[int] = None,
+    ) -> None:
+        super().__init__()
+        self.input_dim = input_dim
+        self.codebook = codebook
+        self.commitment = commitment
+        self.ort_reg_weight = ort_reg_weight
+        self.ort_reg_max_codes = ort_reg_max_codes
+        require_projection = self.codebook.dim != self.input_dim
+        self.project_in = (
+            nn.Linear(self.input_dim, self.codebook.dim)
+            if require_projection
+            else nn.Identity()
+        )
+        self.project_out = (
+            nn.Linear(self.codebook.dim, self.input_dim)
+            if require_projection
+            else nn.Identity()
+        )
+
+    def forward(self, x: Tensor) -> Tuple[Tensor, Tensor, Tensor]:
+        """Quantizes latent vectors."""
+        H, W = x.shape[-2:]
+        device = x.device
+        x = rearrange(x, "b d h w -> b (h w) d")
+        x = self.project_in(x)
+
+        quantized, indices = self.codebook(x)
+
+        if self.training:
+            loss = F.mse_loss(quantized.detach(), x) * self.commitment
+            quantized = x + (quantized - x).detach()
+            if self.ort_reg_weight > 0:
+                codebook = self.codebook.embeddings
+                num_codes = codebook.shape[0]
+                if num_codes > self.ort_reg_max_codes:
+                    rand_ids = torch.randperm(num_codes, device=device)[
+                        : self.ort_reg_max_codes
+                    ]
+                    codebook = codebook[rand_ids]
+                orthgonal_loss = orthgonal_loss_fn(codebook)
+                loss += self.ort_reg_weight * orthgonal_loss
+        else:
+            loss = torch.tensor([0.0]).type_as(x)
+
+        quantized = self.project_out(quantized)
+        quantized = rearrange(quantized, "b (h w) d -> b d h w", h=H, w=W)
+
+        return quantized, indices, loss
-- 
cgit v1.2.3-70-g09d2