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56 lines
2.5 KiB
Plaintext
56 lines
2.5 KiB
Plaintext
//- 💫 DOCS > API > ANNOTATION > TEXT PROCESSING
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+aside-code("Example").
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from spacy.lang.en import English
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nlp = English()
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tokens = nlp('Some\nspaces and\ttab characters')
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tokens_text = [t.text for t in tokens]
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assert tokens_text == ['Some', '\n', 'spaces', ' ', 'and',
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'\t', 'tab', 'characters']
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p
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| Tokenization standards are based on the
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| #[+a("https://catalog.ldc.upenn.edu/LDC2013T19") OntoNotes 5] corpus.
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| The tokenizer differs from most by including
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| #[strong tokens for significant whitespace]. Any sequence of
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| whitespace characters beyond a single space (#[code ' ']) is included
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| as a token. The whitespace tokens are useful for much the same reason
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| punctuation is – it's often an important delimiter in the text. By
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| preserving it in the token output, we are able to maintain a simple
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| alignment between the tokens and the original string, and we ensure
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| that #[strong no information is lost] during processing.
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+h(3, "lemmatization") Lemmatization
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+aside("Examples")
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| In English, this means:#[br]
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| #[strong Adjectives]: happier, happiest → happy#[br]
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| #[strong Adverbs]: worse, worst → badly#[br]
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| #[strong Nouns]: dogs, children → dog, child#[br]
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| #[strong Verbs]: writes, wirting, wrote, written → write
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p
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| A lemma is the uninflected form of a word. The English lemmatization
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| data is taken from #[+a("https://wordnet.princeton.edu") WordNet].
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| Lookup tables are taken from
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| #[+a("http://www.lexiconista.com/datasets/lemmatization/") Lexiconista].
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| spaCy also adds a #[strong special case for pronouns]: all pronouns
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| are lemmatized to the special token #[code -PRON-].
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+infobox("About spaCy's custom pronoun lemma", "⚠️")
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| Unlike verbs and common nouns, there's no clear base form of a personal
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| pronoun. Should the lemma of "me" be "I", or should we normalize person
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| as well, giving "it" — or maybe "he"? spaCy's solution is to introduce a
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| novel symbol, #[code -PRON-], which is used as the lemma for
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| all personal pronouns.
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+h(3, "sentence-boundary") Sentence boundary detection
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p
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| Sentence boundaries are calculated from the syntactic parse tree, so
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| features such as punctuation and capitalisation play an important but
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| non-decisive role in determining the sentence boundaries. Usually this
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| means that the sentence boundaries will at least coincide with clause
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| boundaries, even given poorly punctuated text.
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