+h(2, "similarity-context") Similarities in context
p
| Aside from spaCy's built-in word vectors, which were trained on a lot of
| text with a wide vocabulary, the parsing, tagging and NER models also
| rely on vector representations of the #[strong meanings of words in context].
| As the first component of the
| #[+a("/docs/usage/language-processing-pipeline") processing pipeline], the
| tensorizer encodes a document's internal meaning representations as an
| array of floats, also called a tensor. This allows spaCy to make a
| reasonable guess at a word's meaning, based on its surrounding words.
| Even if a word hasn't been seen before, spaCy will know #[em something]
| about it. Because spaCy uses a 4-layer convolutional network, the
| tensors are sensitive to up to #[strong four words on either side] of a
| word.
p
| For example, here are three sentences containing the out-of-vocabulary
| word "labrador" in different contexts.
+code.
doc1 = nlp(u"The labrador barked.")
doc2 = nlp(u"The labrador swam.")
doc3 = nlp(u"the labrador people live in canada.")
for doc in [doc1, doc2, doc3]:
labrador = doc[1]
dog = nlp(u"dog")
print(labrador.similarity(dog))
p
| Even though the model has never seen the word "labrador", it can make a
| fairly accurate prediction of its similarity to "dog" in different
| contexts.
+table(["Context", "labrador.similarity(dog)"])
+row
+cell The #[strong labrador] barked.
+cell #[code 0.56] #[+procon("pro")]
+row
+cell The #[strong labrador] swam.
+cell #[code 0.48] #[+procon("con")]
+row
+cell the #[strong labrador] people live in canada.
+cell #[code 0.39] #[+procon("con")]
p
| The same also works for whole documents. Here, the variance of the
| similarities is lower, as all words and their order are taken into
| account. However, the context-specific similarity is often still
| reflected pretty accurately.
+code.
doc1 = nlp(u"Paris is the largest city in France.")
doc2 = nlp(u"Ljubljana is the capital of Lithuania.")
doc3 = nlp(u"An emu is a large bird.")
for doc in [doc1, doc2, doc3]:
for other_doc in [doc1, doc2, doc3]:
print(doc.similarity(other_doc))
p
| Even though the sentences about Paris and Ljubljana consist of different
| words and entities, they both describe the same concept and are seen as
| more similar than the sentence about emus. In this case, even a misspelled
| version of "Ljubljana" would still produce very similar results.
+table
- var examples = {"Paris is the largest city in France.": [1, 0.84, 0.65], "Ljubljana is the capital of Lithuania.": [0.84, 1, 0.52], "An emu is a large bird.": [0.65, 0.52, 1]}
