spaCy/website/docs/api/morphology.md
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* Remove outdated UPOS conversions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

104 lines
3.5 KiB
Markdown

---
title: Morphology
tag: class
source: spacy/morphology.pyx
---
Store the possible morphological analyses for a language, and index them by
hash. To save space on each token, tokens only know the hash of their
morphological analysis, so queries of morphological attributes are delegated to
this class.
## Morphology.\_\_init\_\_ {#init tag="method"}
Create a Morphology object.
> #### Example
>
> ```python
> from spacy.morphology import Morphology
>
> morphology = Morphology(strings)
> ```
| Name | Type | Description |
| --------- | ------------- | ----------------- |
| `strings` | `StringStore` | The string store. |
## Morphology.add {#add tag="method"}
Insert a morphological analysis in the morphology table, if not already present.
The morphological analysis may be provided in the UD FEATS format as a string or
in the tag map dictionary format. Returns the hash of the new analysis.
> #### Example
>
> ```python
> feats = "Feat1=Val1|Feat2=Val2"
> hash = nlp.vocab.morphology.add(feats)
> assert hash == nlp.vocab.strings[feats]
> ```
| Name | Type | Description |
| ---------- | ------------------ | --------------------------- |
| `features` | `Union[Dict, str]` | The morphological features. |
## Morphology.get {#get tag="method"}
> #### Example
>
> ```python
> feats = "Feat1=Val1|Feat2=Val2"
> hash = nlp.vocab.morphology.add(feats)
> assert nlp.vocab.morphology.get(hash) == feats
> ```
Get the FEATS string for the hash of the morphological analysis.
| Name | Type | Description |
| ------- | ---- | --------------------------------------- |
| `morph` | int | The hash of the morphological analysis. |
## Morphology.feats_to_dict {#feats_to_dict tag="staticmethod"}
Convert a string FEATS representation to a dictionary of features and values in
the same format as the tag map.
> #### Example
>
> ```python
> from spacy.morphology import Morphology
> d = Morphology.feats_to_dict("Feat1=Val1|Feat2=Val2")
> assert d == {"Feat1": "Val1", "Feat2": "Val2"}
> ```
| Name | Type | Description |
| ----------- | ---- | ------------------------------------------------------------------ |
| `feats` | str | The morphological features in Universal Dependencies FEATS format. |
| **RETURNS** | dict | The morphological features as a dictionary. |
## Morphology.dict_to_feats {#dict_to_feats tag="staticmethod"}
Convert a dictionary of features and values to a string FEATS representation.
> #### Example
>
> ```python
> from spacy.morphology import Morphology
> f = Morphology.dict_to_feats({"Feat1": "Val1", "Feat2": "Val2"})
> assert f == "Feat1=Val1|Feat2=Val2"
> ```
| Name | Type | Description |
| ------------ | ----------------- | --------------------------------------------------------------------- |
| `feats_dict` | `Dict[str, Dict]` | The morphological features as a dictionary. |
| **RETURNS** | str | The morphological features as in Universal Dependencies FEATS format. |
## Attributes {#attributes}
| Name | Type | Description |
| ------------- | ----- | -------------------------------------------- |
| `FEATURE_SEP` | `str` | The FEATS feature separator. Default is `|`. |
| `FIELD_SEP` | `str` | The FEATS field separator. Default is `=`. |
| `VALUE_SEP` | `str` | The FEATS value separator. Default is `,`. |