1 files changed, 111 insertions, 0 deletions
diff --git a/src/text_recognizer/models/transformer_encoder_model.py b/src/text_recognizer/models/transformer_encoder_model.py
new file mode 100644
index 0000000..e35e298
--- /dev/null
+++ b/src/text_recognizer/models/transformer_encoder_model.py
@@ -0,0 +1,111 @@
+"""Defines the CNN-Transformer class."""
+from typing import Callable, Dict, List, Optional, Tuple, Type, Union
+
+import numpy as np
+import torch
+from torch import nn
+from torch import Tensor
+from torch.utils.data import Dataset
+from torchvision.transforms import ToTensor
+
+from text_recognizer.datasets import EmnistMapper
+from text_recognizer.models.base import Model
+
+
+class TransformerEncoderModel(Model):
+    """A class for only using the encoder part in the sequence modelling."""
+
+    def __init__(
+        self,
+        network_fn: Type[nn.Module],
+        dataset: Type[Dataset],
+        network_args: Optional[Dict] = None,
+        dataset_args: Optional[Dict] = None,
+        metrics: Optional[Dict] = None,
+        criterion: Optional[Callable] = None,
+        criterion_args: Optional[Dict] = None,
+        optimizer: Optional[Callable] = None,
+        optimizer_args: Optional[Dict] = None,
+        lr_scheduler: Optional[Callable] = None,
+        lr_scheduler_args: Optional[Dict] = None,
+        swa_args: Optional[Dict] = None,
+        device: Optional[str] = None,
+    ) -> None:
+        super().__init__(
+            network_fn,
+            dataset,
+            network_args,
+            dataset_args,
+            metrics,
+            criterion,
+            criterion_args,
+            optimizer,
+            optimizer_args,
+            lr_scheduler,
+            lr_scheduler_args,
+            swa_args,
+            device,
+        )
+        # self.init_token = dataset_args["args"]["init_token"]
+        self.pad_token = dataset_args["args"]["pad_token"]
+        self.eos_token = dataset_args["args"]["eos_token"]
+        if network_args is not None:
+            self.max_len = network_args["max_len"]
+        else:
+            self.max_len = 128
+
+        if self._mapper is None:
+            self._mapper = EmnistMapper(
+                # init_token=self.init_token,
+                pad_token=self.pad_token,
+                eos_token=self.eos_token,
+            )
+        self.tensor_transform = ToTensor()
+
+        self.softmax = nn.Softmax(dim=2)
+
+    @torch.no_grad()
+    def _generate_sentence(self, image: Tensor) -> Tuple[List, float]:
+        logits = self.network(image)
+        # Convert logits to probabilities.
+        probs = self.softmax(logits).squeeze(0)
+
+        confidence, pred_tokens = probs.max(1)
+        pred_tokens = pred_tokens
+
+        eos_index = torch.nonzero(
+            pred_tokens == self._mapper(self.eos_token), as_tuple=False,
+        )
+
+        eos_index = eos_index[0].item() if eos_index.nelement() else -1
+
+        predicted_characters = "".join(
+            [self.mapper(x) for x in pred_tokens[:eos_index].tolist()]
+        )
+
+        confidence = np.min(confidence.tolist())
+
+        return predicted_characters, confidence
+
+    @torch.no_grad()
+    def predict_on_image(self, image: Union[np.ndarray, Tensor]) -> Tuple[str, float]:
+        """Predict on a single input."""
+        self.eval()
+
+        if image.dtype == np.uint8:
+            # Converts an image with range [0, 255] with to Pytorch Tensor with range [0, 1].
+            image = self.tensor_transform(image)
+
+        # Rescale image between 0 and 1.
+        if image.dtype == torch.uint8:
+            # If the image is an unscaled tensor.
+            image = image.type("torch.FloatTensor") / 255
+
+        # Put the image tensor on the device the model weights are on.
+        image = image.to(self.device)
+
+        (predicted_characters, confidence_of_prediction,) = self._generate_sentence(
+            image
+        )
+
+        return predicted_characters, confidence_of_prediction