spaCy/spacy/lang/en/lemmatizer.py
Adriane Boyd e962784531
Add Lemmatizer and simplify related components (#5848)
* Add Lemmatizer and simplify related components

* Add `Lemmatizer` pipe with `lookup` and `rule` modes using the
`Lookups` tables.
* Reduce `Tagger` to a simple tagger that sets `Token.tag` (no pos or lemma)
* Reduce `Morphology` to only keep track of morph tags (no tag map, lemmatizer,
or morph rules)
* Remove lemmatizer from `Vocab`
* Adjust many many tests

Differences:

* No default lookup lemmas
* No special treatment of TAG in `from_array` and similar required
* Easier to modify labels in a `Tagger`
* No extra strings added from morphology / tag map

* Fix test

* Initial fix for Lemmatizer config/serialization

* Adjust init test to be more generic

* Adjust init test to force empty Lookups

* Add simple cache to rule-based lemmatizer

* Convert language-specific lemmatizers

Convert language-specific lemmatizers to component lemmatizers. Remove
previous lemmatizer class.

* Fix French and Polish lemmatizers

* Remove outdated UPOS conversions

* Update Russian lemmatizer init in tests

* Add minimal init/run tests for custom lemmatizers

* Add option to overwrite existing lemmas

* Update mode setting, lookup loading, and caching

* Make `mode` an immutable property
* Only enforce strict `load_lookups` for known supported modes
* Move caching into individual `_lemmatize` methods

* Implement strict when lang is not found in lookups

* Fix tables/lookups in make_lemmatizer

* Reallow provided lookups and allow for stricter checks

* Add lookups asset to all Lemmatizer pipe tests

* Rename lookups in lemmatizer init test

* Clean up merge

* Refactor lookup table loading

* Add helper from `load_lemmatizer_lookups` that loads required and
optional lookups tables based on settings provided by a config.

Additional slight refactor of lookups:

* Add `Lookups.set_table` to set a table from a provided `Table`
* Reorder class definitions to be able to specify type as `Table`

* Move registry assets into test methods

* Refactor lookups tables config

Use class methods within `Lemmatizer` to provide the config for
particular modes and to load the lookups from a config.

* Add pipe and score to lemmatizer

* Simplify Tagger.score

* Add missing import

* Clean up imports and auto-format

* Remove unused kwarg

* Tidy up and auto-format

* Update docstrings for Lemmatizer

Update docstrings for Lemmatizer.

Additionally modify `is_base_form` API to take `Token` instead of
individual features.

* Update docstrings

* Remove tag map values from Tagger.add_label

* Update API docs

* Fix relative link in Lemmatizer API docs
2020-08-07 15:27:13 +02:00

44 lines
1.5 KiB
Python

from typing import Optional
from ...pipeline import Lemmatizer
from ...tokens import Token
class EnglishLemmatizer(Lemmatizer):
"""English lemmatizer. Only overrides is_base_form.
"""
def is_base_form(self, token: Token) -> bool:
"""
Check whether we're dealing with an uninflected paradigm, so we can
avoid lemmatization entirely.
univ_pos (unicode / int): The token's universal part-of-speech tag.
morphology (dict): The token's morphological features following the
Universal Dependencies scheme.
"""
univ_pos = token.pos_.lower()
morphology = token.morph.to_dict()
if univ_pos == "noun" and morphology.get("Number") == "Sing":
return True
elif univ_pos == "verb" and morphology.get("VerbForm") == "Inf":
return True
# This maps 'VBP' to base form -- probably just need 'IS_BASE'
# morphology
elif univ_pos == "verb" and (
morphology.get("VerbForm") == "Fin"
and morphology.get("Tense") == "Pres"
and morphology.get("Number") is None
):
return True
elif univ_pos == "adj" and morphology.get("Degree") == "Pos":
return True
elif morphology.get("VerbForm") == "Inf":
return True
elif morphology.get("VerbForm") == "None":
return True
elif morphology.get("Degree") == "Pos":
return True
else:
return False