From 7c4de6d88664d2ea1b084f316a11896dde3e1150 Mon Sep 17 00:00:00 2001
From: aktersnurra <gustaf.rydholm@gmail.com>
Date: Tue, 23 Jun 2020 22:39:54 +0200
Subject: latest

---
 src/text_recognizer/models/character_model.py | 71 +++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 src/text_recognizer/models/character_model.py

(limited to 'src/text_recognizer/models/character_model.py')

diff --git a/src/text_recognizer/models/character_model.py b/src/text_recognizer/models/character_model.py
new file mode 100644
index 0000000..1570344
--- /dev/null
+++ b/src/text_recognizer/models/character_model.py
@@ -0,0 +1,71 @@
+"""Defines the CharacterModel class."""
+from typing import Callable, Dict, Optional, Tuple
+
+import numpy as np
+import torch
+from torch import nn
+from torchvision.transforms import ToTensor
+
+from text_recognizer.datasets.emnist_dataset import load_emnist_mapping
+from text_recognizer.models.base import Model
+from text_recognizer.networks.mlp import mlp
+
+
+class CharacterModel(Model):
+    """Model for predicting characters from images."""
+
+    def __init__(
+        self,
+        network_fn: Callable,
+        network_args: Dict,
+        data_loader_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,
+        device: Optional[str] = None,
+    ) -> None:
+        """Initializes the CharacterModel."""
+
+        super().__init__(
+            network_fn,
+            data_loader_args,
+            network_args,
+            metrics,
+            criterion,
+            optimizer,
+            device,
+        )
+        self.emnist_mapping = self.mapping()
+        self.eval()
+
+    def mapping(self) -> Dict:
+        """Mapping between integers and classes."""
+        mapping = load_emnist_mapping()
+        return mapping
+
+    def predict_on_image(self, image: np.ndarray) -> Tuple[str, float]:
+        """Character prediction on an image.
+
+        Args:
+            image (np.ndarray): An image containing a character.
+
+        Returns:
+            Tuple[str, float]: The predicted character and the confidence in the prediction.
+
+        """
+        if image.dtype == np.uint8:
+            image = (image / 255).astype(np.float32)
+
+        # Conver to Pytorch Tensor.
+        image = ToTensor(image)
+
+        prediction = self.network(image)
+        index = torch.argmax(prediction, dim=1)
+        confidence_of_prediction = prediction[index]
+        predicted_character = self.emnist_mapping[index]
+
+        return predicted_character, confidence_of_prediction
-- 
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