mirror of https://github.com/explosion/spaCy.git
250 lines
13 KiB
Markdown
250 lines
13 KiB
Markdown
---
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title: Tokenizer
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teaser: Segment text into words, punctuations marks etc.
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tag: class
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source: spacy/tokenizer.pyx
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---
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Segment text, and create `Doc` objects with the discovered segment boundaries.
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For a deeper understanding, see the docs on
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[how spaCy's tokenizer works](/usage/linguistic-features#how-tokenizer-works).
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## Tokenizer.\_\_init\_\_ {#init tag="method"}
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Create a `Tokenizer`, to create `Doc` objects given unicode text. For examples
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of how to construct a custom tokenizer with different tokenization rules, see
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the
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[usage documentation](https://spacy.io/usage/linguistic-features#native-tokenizers).
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> #### Example
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>
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> ```python
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> # Construction 1
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> from spacy.tokenizer import Tokenizer
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> from spacy.lang.en import English
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> nlp = English()
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> # Create a blank Tokenizer with just the English vocab
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> tokenizer = Tokenizer(nlp.vocab)
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>
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> # Construction 2
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> from spacy.lang.en import English
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> nlp = English()
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> # Create a Tokenizer with the default settings for English
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> # including punctuation rules and exceptions
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> tokenizer = nlp.Defaults.create_tokenizer(nlp)
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> ```
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| Name | Type | Description |
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| ---------------- | ----------- | ----------------------------------------------------------------------------------------------------------------------------- |
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| `vocab` | `Vocab` | A storage container for lexical types. |
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| `rules` | dict | Exceptions and special-cases for the tokenizer. |
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| `prefix_search` | callable | A function matching the signature of `re.compile(string).search` to match prefixes. |
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| `suffix_search` | callable | A function matching the signature of `re.compile(string).search` to match suffixes. |
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| `infix_finditer` | callable | A function matching the signature of `re.compile(string).finditer` to find infixes. |
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| `token_match` | callable | A function matching the signature of `re.compile(string).match to find token matches. |
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| **RETURNS** | `Tokenizer` | The newly constructed object. |
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## Tokenizer.\_\_call\_\_ {#call tag="method"}
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Tokenize a string.
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> #### Example
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>
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> ```python
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> tokens = tokenizer("This is a sentence")
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> assert len(tokens) == 4
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> ```
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| Name | Type | Description |
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| ----------- | ------- | --------------------------------------- |
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| `string` | unicode | The string to tokenize. |
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| **RETURNS** | `Doc` | A container for linguistic annotations. |
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## Tokenizer.pipe {#pipe tag="method"}
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Tokenize a stream of texts.
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> #### Example
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>
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> ```python
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> texts = ["One document.", "...", "Lots of documents"]
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> for doc in tokenizer.pipe(texts, batch_size=50):
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> pass
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> ```
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| Name | Type | Description |
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| ------------ | ----- | ---------------------------------------------------------------------------- |
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| `texts` | - | A sequence of unicode texts. |
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| `batch_size` | int | The number of texts to accumulate in an internal buffer. Defaults to `1000`. |
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| **YIELDS** | `Doc` | A sequence of Doc objects, in order. |
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## Tokenizer.find_infix {#find_infix tag="method"}
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Find internal split points of the string.
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| Name | Type | Description |
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| ----------- | ------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `string` | unicode | The string to split. |
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| **RETURNS** | list | A list of `re.MatchObject` objects that have `.start()` and `.end()` methods, denoting the placement of internal segment separators, e.g. hyphens. |
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## Tokenizer.find_prefix {#find_prefix tag="method"}
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Find the length of a prefix that should be segmented from the string, or `None`
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if no prefix rules match.
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| Name | Type | Description |
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| ----------- | ------- | ------------------------------------------------------ |
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| `string` | unicode | The string to segment. |
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| **RETURNS** | int | The length of the prefix if present, otherwise `None`. |
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## Tokenizer.find_suffix {#find_suffix tag="method"}
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Find the length of a suffix that should be segmented from the string, or `None`
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if no suffix rules match.
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| Name | Type | Description |
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| ----------- | ------------ | ------------------------------------------------------ |
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| `string` | unicode | The string to segment. |
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| **RETURNS** | int / `None` | The length of the suffix if present, otherwise `None`. |
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## Tokenizer.add_special_case {#add_special_case tag="method"}
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Add a special-case tokenization rule. This mechanism is also used to add custom
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tokenizer exceptions to the language data. See the usage guide on
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[adding languages](/usage/adding-languages#tokenizer-exceptions) and
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[linguistic features](/usage/linguistic-features#special-cases) for more details
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and examples.
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> #### Example
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>
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> ```python
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> from spacy.attrs import ORTH, NORM
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> case = [{ORTH: "do"}, {ORTH: "n't", NORM: "not"}]
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> tokenizer.add_special_case("don't", case)
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> ```
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| Name | Type | Description |
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| ------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| `string` | unicode | The string to specially tokenize. |
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| `token_attrs` | iterable | A sequence of dicts, where each dict describes a token and its attributes. The `ORTH` fields of the attributes must exactly match the string when they are concatenated. |
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## Tokenizer.explain {#explain tag="method"}
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Tokenize a string with a slow debugging tokenizer that provides information
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about which tokenizer rule or pattern was matched for each token. The tokens
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produced are identical to `Tokenizer.__call__` except for whitespace tokens.
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> #### Example
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>
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> ```python
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> tok_exp = nlp.tokenizer.explain("(don't)")
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> assert [t[0] for t in tok_exp] == ["PREFIX", "SPECIAL-1", "SPECIAL-2", "SUFFIX"]
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> assert [t[1] for t in tok_exp] == ["(", "do", "n't", ")"]
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> ```
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| Name | Type | Description |
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| ------------| -------- | --------------------------------------------------- |
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| `string` | unicode | The string to tokenize with the debugging tokenizer |
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| **RETURNS** | list | A list of `(pattern_string, token_string)` tuples |
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## Tokenizer.to_disk {#to_disk tag="method"}
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Serialize the tokenizer to disk.
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> #### Example
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>
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> ```python
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> tokenizer = Tokenizer(nlp.vocab)
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> tokenizer.to_disk("/path/to/tokenizer")
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> ```
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| Name | Type | Description |
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| --------- | ---------------- | --------------------------------------------------------------------------------------------------------------------- |
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| `path` | unicode / `Path` | A path to a directory, which will be created if it doesn't exist. Paths may be either strings or `Path`-like objects. |
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| `exclude` | list | String names of [serialization fields](#serialization-fields) to exclude. |
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## Tokenizer.from_disk {#from_disk tag="method"}
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Load the tokenizer from disk. Modifies the object in place and returns it.
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> #### Example
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>
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> ```python
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> tokenizer = Tokenizer(nlp.vocab)
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> tokenizer.from_disk("/path/to/tokenizer")
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> ```
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| Name | Type | Description |
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| ----------- | ---------------- | -------------------------------------------------------------------------- |
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| `path` | unicode / `Path` | A path to a directory. Paths may be either strings or `Path`-like objects. |
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| `exclude` | list | String names of [serialization fields](#serialization-fields) to exclude. |
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| **RETURNS** | `Tokenizer` | The modified `Tokenizer` object. |
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## Tokenizer.to_bytes {#to_bytes tag="method"}
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> #### Example
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>
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> ```python
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> tokenizer = tokenizer(nlp.vocab)
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> tokenizer_bytes = tokenizer.to_bytes()
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> ```
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Serialize the tokenizer to a bytestring.
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| Name | Type | Description |
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| ----------- | ----- | ------------------------------------------------------------------------- |
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| `exclude` | list | String names of [serialization fields](#serialization-fields) to exclude. |
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| **RETURNS** | bytes | The serialized form of the `Tokenizer` object. |
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## Tokenizer.from_bytes {#from_bytes tag="method"}
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Load the tokenizer from a bytestring. Modifies the object in place and returns
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it.
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> #### Example
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>
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> ```python
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> tokenizer_bytes = tokenizer.to_bytes()
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> tokenizer = Tokenizer(nlp.vocab)
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> tokenizer.from_bytes(tokenizer_bytes)
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> ```
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| Name | Type | Description |
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| ------------ | ----------- | ------------------------------------------------------------------------- |
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| `bytes_data` | bytes | The data to load from. |
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| `exclude` | list | String names of [serialization fields](#serialization-fields) to exclude. |
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| **RETURNS** | `Tokenizer` | The `Tokenizer` object. |
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## Attributes {#attributes}
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| Name | Type | Description |
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| ---------------- | ------- | --------------------------------------------------------------------------------------------------------------------------- |
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| `vocab` | `Vocab` | The vocab object of the parent `Doc`. |
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| `prefix_search` | - | A function to find segment boundaries from the start of a string. Returns the length of the segment, or `None`. |
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| `suffix_search` | - | A function to find segment boundaries from the end of a string. Returns the length of the segment, or `None`. |
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| `infix_finditer` | - | A function to find internal segment separators, e.g. hyphens. Returns a (possibly empty) list of `re.MatchObject` objects. |
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| `token_match` | - | A function matching the signature of `re.compile(string).match to find token matches. Returns an `re.MatchObject` or `None. |
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| `rules` | dict | A dictionary of tokenizer exceptions and special cases. |
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## Serialization fields {#serialization-fields}
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During serialization, spaCy will export several data fields used to restore
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different aspects of the object. If needed, you can exclude them from
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serialization by passing in the string names via the `exclude` argument.
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> #### Example
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>
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> ```python
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> data = tokenizer.to_bytes(exclude=["vocab", "exceptions"])
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> tokenizer.from_disk("./data", exclude=["token_match"])
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> ```
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| Name | Description |
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| ---------------- | --------------------------------- |
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| `vocab` | The shared [`Vocab`](/api/vocab). |
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| `prefix_search` | The prefix rules. |
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| `suffix_search` | The suffix rules. |
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| `infix_finditer` | The infix rules. |
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| `token_match` | The token match expression. |
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| `exceptions` | The tokenizer exception rules. |
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