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README.md

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-license: mit
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+# Speliuk
+
+A more accurate spelling correction for the Ukrainian language.
+
+## Motivation
+
+When using a spell checker in systems that perform an automatic spelling correction without human verification, the following questions arise:
+- How to avoid false correction, i.e. when a real word that is not present in a vocabulary is corrected? This is especially viable for fusional languages such as Ukrainian.
+- How to find a single best correction for a misspelled word? Many spell checkers rely on the frequency of candidates and their edit distance discarding the surrounding context.
+
+To address these issues, we propose a system that is compatible with any spell checker but focuses on precision over recall.<br>
+We improve the accuracy of a spell checker by using these complimentary models:
+- [KenLM](https://github.com/kpu/kenlm). The model is used for fast perplexity calculation to find the best candidate for a misspelled word.
+- Transfomer-based NER pipeline to detect misspelled words.
+- [SymSpell](https://github.com/wolfgarbe/SymSpell). As of now, this is the only supported spell checker.
+
+## Installation
+
+1. For CPU-only inference, install the CPU version of [PyTorch](https://pytorch.org/get-started/locally/).
+2. Make sure you can compile Python extension modules (required for KenLM). If you are on Linux, you can install them like this:
+```
+sudo apt-get install python-dev
+```
+3. Install Speliuk:
+```
+pip install speliuk
+```
+
+## Usage
+
+By default, Speliuk will use pre-trained models stored on [Hugging Face](https://huggingface.co/BonySmoke/Speliuk/tree/main).
+
+```python
+>>> from speliuk.correct import Speliuk
+>>> speliuk = Speliuk()
+>>> speliuk.load()
+>>> speliuk.correct("то він моее це зраабити для меніе?")
+Correction(corrected_text='то він може це зробити для мене?', annotations=[Annotation(start=7, end=11, source_text='моее', suggestions=['може'], meta={}), Annotation(start=15, end=23, source_text='зраабити', suggestions=['зробити'], meta={}), Annotation(start=28, end=33, source_text='меніе', suggestions=['мене'], meta={})])
+```
+
+Speliuk can also be used directly from a spaCy model:
+```python
+>>> import spacy
+>>> from speliuk.correct import CorrectionPipe
+>>> nlp = spacy.blank('uk')
+>>> nlp.add_pipe('speliuk', config=dict(spacy_spelling_model_path='/my/custom/model'))
+>>> doc = nlp("то він моее це зраабити для меніе?")
+>>> doc._.speliuk_corrected
+'то він може це зробити для мене?'
+>>> doc.spans["speliuk_errors"]
+[моее, зраабити, меніе]
+```
+
+## Training Details
+
+### Spelling Error Detection
+
+To detect spelling errors, a spaCy NER model is used.
+
+It was trained on a combination of synthetic and golden data:
+- For synthetic data generation, we used [UberText](https://lang.org.ua/en/ubertext/) as base texts and [nlpaug](https://github.com/makcedward/nlpaug) for errors generation. In total, 10k samples from different categories were used.
+- For golden data, we used spelling errors from the [UA-GEC](https://github.com/grammarly/ua-gec) corpus.
+
+### Perplexity Calculation
+
+We used KenLM for quick perplexity calculation. We used an existing model [Yehor/kenlm-uk](https://huggingface.co/Yehor/kenlm-uk) trained on UberText.
+
+### Spell Checker
+
+We used [SymSpell](https://github.com/wolfgarbe/SymSpell) for error correction. The dictionary consists of 500k most frequent words from the UberText corpus.