💥 RuErrant
-------------------

RuERRANT is an adaptation of the  `ERRANT metric <https://github.com/chrisjbryant/errant>`_ to the Russian language. The adaptation was primarily done in https://github.com/Askinkaty/errant and further developed within SAGE. The changes to the original ERRANT implementation for English are the following:

1. Basic parsing model changed to Spacy's `ru_core_news_lg`.
2. Included a dictionary of Russian words (main forms).
3. Introduced detection of error correction types specific for Russian (degrees of adjectives, verb aspect).
4. [our contribution] Introduced a simplified error correction typology:
    - `CASE`: spelling corrections including only character case change;
    - `PUNCT`: punctuation corrections;
    - `YO`: spelling corrections regarding "е"/"ё" substitutions;
    - `SPELL`: all other word-level spelling corrections.
5. [our contribution] Introduced detection of multiple error correction types per word, e.g. "федор" -> "Фёдор" contains both CASE and YO corrections.
6. [our contribution] Introduced detection of inner word punctuation corrections which covers joint ("AB") vs. hyphen ("A-B") vs. space ("A B") word spelling. Corrections of this type are attributed to the `SPELL` category.

Scoring
^^^^^^^^

To score model's corrections against gold corrections, use a Scorer instance:

.. code-block:: python

    from sage.evaluation.scorer import Scorer

    s = Scorer()

    s.score(
        ["спел Кейс ее .", "спел Кейс ее ."],
        ["спелл кейс её !", "спелл кейс её !"],
        ["спел кейс её .", "спелл Кейс ее !"],
        metrics=["errant"]
    )
    >>> {'CASE_Precision': 100.0, 'CASE_Recall': 50.0, 'CASE_F1': 66.67,
         'YO_Precision': 100.0, 'YO_Recall': 50.0, 'YO_F1': 66.67,
         'SPELL_Precision': 100.0, 'SPELL_Recall': 50.0, 'SPELL_F1': 66.67,
         'PUNCT_Precision': 100.0, 'PUNCT_Recall': 50.0, 'PUNCT_F1': 66.67}

