From e388cd95c77d37a51324cff9d84a809421bf97d3 Mon Sep 17 00:00:00 2001
From: Gustaf Rydholm <gustaf.rydholm@gmail.com>
Date: Thu, 8 Apr 2021 23:38:03 +0200
Subject: Bug fixes word pieces

---
 text_recognizer/data/base_dataset.py     |  2 +-
 text_recognizer/data/iam.py              |  1 -
 text_recognizer/data/iam_preprocessor.py | 28 +++++++++++++++++++++-------
 text_recognizer/data/transforms.py       |  6 +++---
 4 files changed, 25 insertions(+), 12 deletions(-)

(limited to 'text_recognizer/data')

diff --git a/text_recognizer/data/base_dataset.py b/text_recognizer/data/base_dataset.py
index d00daaf..8d644d4 100644
--- a/text_recognizer/data/base_dataset.py
+++ b/text_recognizer/data/base_dataset.py
@@ -67,7 +67,7 @@ def convert_strings_to_labels(
     labels = torch.ones((len(strings), length), dtype=torch.long) * mapping["<p>"]
     for i, string in enumerate(strings):
         tokens = list(string)
-        tokens = ["<s>", *tokens, "</s>"]
+        tokens = ["<s>", *tokens, "<e>"]
         for j, token in enumerate(tokens):
             labels[i, j] = mapping[token]
     return labels
diff --git a/text_recognizer/data/iam.py b/text_recognizer/data/iam.py
index 01272ba..261c8d3 100644
--- a/text_recognizer/data/iam.py
+++ b/text_recognizer/data/iam.py
@@ -7,7 +7,6 @@ import zipfile
 
 from boltons.cacheutils import cachedproperty
 from loguru import logger
-from PIL import Image
 import toml
 
 from text_recognizer.data.base_data_module import BaseDataModule, load_and_print_info
diff --git a/text_recognizer/data/iam_preprocessor.py b/text_recognizer/data/iam_preprocessor.py
index 3844419..d85787e 100644
--- a/text_recognizer/data/iam_preprocessor.py
+++ b/text_recognizer/data/iam_preprocessor.py
@@ -47,8 +47,6 @@ def load_metadata(
 class Preprocessor:
     """A preprocessor for the IAM dataset."""
 
-    # TODO: add lower case only to when generating...
-
     def __init__(
         self,
         data_dir: Union[str, Path],
@@ -57,10 +55,12 @@ class Preprocessor:
         lexicon_path: Optional[Union[str, Path]] = None,
         use_words: bool = False,
         prepend_wordsep: bool = False,
+        special_tokens: Optional[List[str]] = None,
     ) -> None:
         self.wordsep = "▁"
         self._use_word = use_words
         self._prepend_wordsep = prepend_wordsep
+        self.special_tokens = special_tokens if special_tokens is not None else None
 
         self.data_dir = Path(data_dir)
 
@@ -88,6 +88,10 @@ class Preprocessor:
         else:
             self.lexicon = None
 
+        if self.special_tokens is not None:
+            self.tokens += self.special_tokens
+            self.graphemes += self.special_tokens
+
         self.graphemes_to_index = {t: i for i, t in enumerate(self.graphemes)}
         self.tokens_to_index = {t: i for i, t in enumerate(self.tokens)}
         self.num_features = num_features
@@ -115,21 +119,31 @@ class Preprocessor:
                     continue
                 self.text.append(example["text"].lower())
 
-    def to_index(self, line: str) -> torch.LongTensor:
-        """Converts text to a tensor of indices."""
+
+    def _to_index(self, line: str) -> torch.LongTensor:
+        if line in self.special_tokens:
+            return torch.LongTensor([self.tokens_to_index[line]])
         token_to_index = self.graphemes_to_index
         if self.lexicon is not None:
             if len(line) > 0:
                 # If the word is not found in the lexicon, fall back to letters.
-                line = [
+                tokens = [
                     t
                     for w in line.split(self.wordsep)
                     for t in self.lexicon.get(w, self.wordsep + w)
                 ]
             token_to_index = self.tokens_to_index
         if self._prepend_wordsep:
-            line = itertools.chain([self.wordsep], line)
-        return torch.LongTensor([token_to_index[t] for t in line])
+            tokens = itertools.chain([self.wordsep], tokens)
+        return torch.LongTensor([token_to_index[t] for t in tokens])
+
+    def to_index(self, line: str) -> torch.LongTensor:
+        """Converts text to a tensor of indices."""
+        if self.special_tokens is not None:
+            pattern = f"({'|'.join(self.special_tokens)})"
+            lines = list(filter(None, re.split(pattern, line)))
+            return torch.cat([self._to_index(l) for l in lines])
+        return self._to_index(line)
 
     def to_text(self, indices: List[int]) -> str:
         """Converts indices to text."""
diff --git a/text_recognizer/data/transforms.py b/text_recognizer/data/transforms.py
index 616e236..297c953 100644
--- a/text_recognizer/data/transforms.py
+++ b/text_recognizer/data/transforms.py
@@ -23,12 +23,12 @@ class ToLower:
 class ToCharcters:
     """Converts integers to characters."""
 
-    def __init__(self) -> None:
-        self.mapping, _, _ = emnist_mapping()
+    def __init__(self, extra_symbols: Optional[List[str]] = None) -> None:
+        self.mapping, _, _ = emnist_mapping(extra_symbols)
 
     def __call__(self, y: Tensor) -> str:
         """Converts a Tensor to a str."""
-        return "".join([self.mapping(int(i)) for i in y]).strip("<p>").replace(" ", "▁")
+        return "".join([self.mapping[int(i)] for i in y]).replace(" ", "▁")
 
 
 class WordPieces:
-- 
cgit v1.2.3-70-g09d2