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Update vectors and similarity usage guide

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ines 2017-11-01 01:25:17 +01:00
parent 37e62ab0e2
commit 07d02c3304
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1
website/usage/_data.json
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@ -116,7 +116,6 @@
"next": "text-classification",
"menu": {
"Basics": "basics",
"Similarity in Context": "in-context",
"Custom Vectors": "custom",
"GPU Usage": "gpu"
}

124
website/usage/_vectors-similarity/_basics.jade
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@ -13,3 +13,127 @@
include ../_spacy-101/_similarity
include ../_spacy-101/_word-vectors
+h(3, "in-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("/usage/processing-pipelines") 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("yes", "similar")]
+row
+cell The #[strong labrador] swam.
+cell #[code 0.48] #[+procon("no", "dissimilar")]
+row
+cell the #[strong labrador] people live in canada.
+cell #[code 0.39] #[+procon("no", "dissimilar")]
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"Vilnius 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 Vilnius 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 "Vilnius" would still produce very similar results.
+table
- var examples = {"Paris is the largest city in France.": [1, 0.85, 0.65], "Vilnius is the capital of Lithuania.": [0.85, 1, 0.55], "An emu is a large bird.": [0.65, 0.55, 1]}
- var counter = 0
+row
+row
+cell
for _, label in examples
+cell=label
each cells, label in examples
+row(counter ? null : "divider")
+cell=label
for cell in cells
+cell.u-text-center
- var result = cell < 0.7 ? ["no", "dissimilar"] : cell != 1 ? ["yes", "similar"] : ["neutral", "identical"]
| #[code=cell.toFixed(2)] #[+procon(...result)]
- counter++
p
| Sentences that consist of the same words in different order will likely
| be seen as very similar – but never identical.
+code.
docs = [nlp(u"dog bites man"), nlp(u"man bites dog"),
nlp(u"man dog bites"), nlp(u"dog man bites")]
for doc in docs:
for other_doc in docs:
print(doc.similarity(other_doc))
p
| Interestingly, "man bites dog" and "man dog bites" are seen as slightly
| more similar than "man bites dog" and "dog bites man". This may be a
| conincidence – or the result of "man" being interpreted as both sentence's
| subject.
+table
- var examples = {"dog bites man": [1, 0.9, 0.89, 0.92], "man bites dog": [0.9, 1, 0.93, 0.9], "man dog bites": [0.89, 0.93, 1, 0.92], "dog man bites": [0.92, 0.9, 0.92, 1]}
- var counter = 0
+row("head")
+cell
for _, label in examples
+cell.u-text-center=label
each cells, label in examples
+row(counter ? null : "divider")
+cell=label
for cell in cells
+cell.u-text-center
- var result = cell < 0.7 ? ["no", "dissimilar"] : cell != 1 ? ["yes", "similar"] : ["neutral", "identical"]
| #[code=cell.toFixed(2)] #[+procon(...result)]
- counter++

167
website/usage/_vectors-similarity/_custom.jade
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@ -1,49 +1,137 @@
//- 💫 DOCS > USAGE > VECTORS & SIMILARITY > CUSTOM VECTORS
p
| By default, #[+api("token#vector") #[code Token.vector]] returns the
| vector for its underlying #[+api("lexeme") #[code Lexeme]], while
| #[+api("doc#vector") #[code Doc.vector]] and
| #[+api("span#vector") #[code Span.vector]] return an average of the
| vectors of their tokens. You can customize these
| behaviours by modifying the #[code doc.user_hooks],
| #[code doc.user_span_hooks] and #[code doc.user_token_hooks]
| dictionaries.
| Word vectors let you import knowledge from raw text into your model. The
| knowledge is represented as a table of numbers, with one row per term in
| your vocabulary. If two terms are used in similar contexts, the algorithm
| that learns the vectors should assign them
| #[strong rows that are quite similar], while words that are used in
| different contexts will have quite different values. This lets you use
| the row-values assigned to the words as a kind of dictionary, to tell you
| some things about what the words in your text mean.
+infobox
| For more details on #[strong adding hooks] and #[strong overwriting] the
| built-in #[code Doc], #[code Span] and #[code Token] methods, see the
| usage guide on #[+a("/usage/processing-pipelines#user-hooks") user hooks].
p
| Word vectors are particularly useful for terms which
| #[strong aren&apos;t well represented in your labelled training data].
| For instance, if you're doing named entity recognition, there will always
| be lots of names that you don't have examples of. For instance, imagine
| your training data happens to contain some examples of the term
| "Microsoft", but it doesn't contain any examples of the term "Symantec".
| In your raw text sample, there are plenty of examples of both terms, and
| they're used in similar contexts. The word vectors make that fact
| available to the entity recognition model. It still won't see examples of
| "Symantec" labelled as a company. However, it'll see that "Symantec" has
| a word vector that usually corresponds to company terms, so it can
| #[strong make the inference].
p
| In order to make best use of the word vectors, you want the word vectors
| table to cover a #[strong very large vocabulary]. However, most words are
| rare, so most of the rows in a large word vectors table will be accessed
| very rarely, or never at all. You can usually cover more than
| #[strong 95% of the tokens] in your corpus with just
| #[strong a few thousand rows] in the vector table. However, it's those
| #[strong 5% of rare terms] where the word vectors are
| #[strong most useful]. The problem is that increasing the size of the
| vector table produces rapidly diminishing returns in coverage over these
| rare terms.
+h(3, "custom-vectors-coverage") Optimising vector coverage
+tag-new(2)
p
| To help you strike a good balance between coverage and memory usage,
| spaCy's #[+api("vectors") #[code Vectors]] class lets you map
| #[strong multiple keys] to the #[strong same row] of the table. If
| you're using the #[+api("cli#vocab") #[code spacy vocab]] command to
| create a vocabulary, pruning the vectors will be taken care of
| automatically. You can also do it manually in the following steps:
+list("numbers")
+item
| Start with a #[strong word vectors model] that covers a huge
| vocabulary. For instance, the
| #[+a("/models/en#en_vectors_web_lg") #[code en_vectors_web_lg]] model
| provides 300-dimensional GloVe vectors for over 1 million terms of
| English.
+item
| If your vocabulary has values set for the #[code Lexeme.prob]
| attribute, the lexemes will be sorted by descending probability to
| determine which vectors to prune. Otherwise, lexemes will be sorted
| by their order in the #[code Vocab].
+item
| Call #[+api("vocab#prune_vectors") #[code Vocab.prune_vectors]] with
| the number of vectors you want to keep.
+code.
nlp = spacy.load('en_vectors_web_lg')
n_vectors = 105000 # number of vectors to keep
removed_words = nlp.vocab.prune_vectors(n_vectors)
assert len(nlp.vocab.vectors) &lt;= n_vectors # unique vectors have been pruned
assert nlp.vocab.vectors.n_keys &gt; n_vectors # but not the total entries
p
| #[+api("vocab#prune_vectors") #[code Vocab.prune_vectors]] reduces the
| current vector table to a given number of unique entries, and returns a
| dictionary containing the removed words, mapped to #[code (string, score)]
| tuples, where #[code string] is the entry the removed word was mapped
| to, and #[code score] the similarity score between the two words.
+code("Removed words").
{
'Shore': ('coast', 0.732257),
'Precautionary': ('caution', 0.490973),
'hopelessness': ('sadness', 0.742366),
'Continous': ('continuous', 0.732549),
'Disemboweled': ('corpse', 0.499432),
'biostatistician': ('scientist', 0.339724),
'somewheres': ('somewheres', 0.402736),
'observing': ('observe', 0.823096),
'Leaving': ('leaving', 1.0)
}
p
| In the example above, the vector for "Shore" was removed and remapped
| to the vector of "coast", which is deemed about 73% similar. "Leaving"
| was remapped to the vector of "leaving", which is identical.
+h(3, "custom-vectors-add") Adding vectors
+tag-new(2)
p
| The new #[+api("vectors") #[code Vectors]] class makes it easy to add
| your own vectors to spaCy. Just like the #[+api("vocab") #[code Vocab]],
| it is initialised with a #[+api("stringstore") #[code StringStore]] or
| a list of strings.
| spaCy's new #[+api("vectors") #[code Vectors]] class greatly improves the
| way word vectors are stored, accessed and used. The data is stored in
| two structures:
+code("Adding vectors one-by-one").
from spacy.strings import StringStore
from spacy.vectors import Vectors
+list
+item
| An array, which can be either on CPU or #[+a("#gpu") GPU].
vector_data = {'dog': numpy.random.uniform(-1, 1, (300,)),
'cat': numpy.random.uniform(-1, 1, (300,)),
'orange': numpy.random.uniform(-1, 1, (300,))}
vectors = Vectors(StringStore(), 300)
for word, vector in vector_data.items():
vectors.add(word, vector)
+item
| A dictionary mapping string-hashes to rows in the table.
p
| You can also add the vector values directly on initialisation:
| Keep in mind that the #[code Vectors] class itself has no
| #[+api("stringstore") #[code StringStore]], so you have to store the
| hash-to-string mapping separately. If you need to manage the strings,
| you should use the #[code Vectors] via the
| #[+api("vocab") #[code Vocab]] class, e.g. #[code vocab.vectors]. To
| add vectors to the vocabulary, you can use the
| #[+api("vocab#set_vector") #[code Vocab.set_vector]] method.
+code("Adding vectors on initialisation").
from spacy.vectors import Vectors
+code("Adding vectors").
from spacy.vocab import Vocab
vector_table = numpy.zeros((3, 300), dtype='f')
vectors = Vectors([u'dog', u'cat', u'orange'], vector_table)
vector_data = {u'dog': numpy.random.uniform(-1, 1, (300,)),
u'cat': numpy.random.uniform(-1, 1, (300,)),
u'orange': numpy.random.uniform(-1, 1, (300,))}
vocab = Vocab()
for word, vector in vector_data.items():
vocab.set_vector(word, vector)
+h(3, "custom-loading-glove") Loading GloVe vectors
+tag-new(2)
@ -89,3 +177,20 @@ p
| #[+api("vocab#set_vector") #[code set_vector]] method.
+github("spacy", "examples/vectors_fast_text.py")
+h(3, "custom-similarity") Using custom similarity methods
p
| By default, #[+api("token#vector") #[code Token.vector]] returns the
| vector for its underlying #[+api("lexeme") #[code Lexeme]], while
| #[+api("doc#vector") #[code Doc.vector]] and
| #[+api("span#vector") #[code Span.vector]] return an average of the
| vectors of their tokens. You can customise these
| behaviours by modifying the #[code doc.user_hooks],
| #[code doc.user_span_hooks] and #[code doc.user_token_hooks]
| dictionaries.
+infobox
| For more details on #[strong adding hooks] and #[strong overwriting] the
| built-in #[code Doc], #[code Span] and #[code Token] methods, see the
| usage guide on #[+a("/usage/processing-pipelines#user-hooks") user hooks].

123
website/usage/_vectors-similarity/_in-context.jade
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@ -1,123 +0,0 @@
//- 💫 DOCS > USAGE > VECTORS & SIMILARITY > 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("/usage/processing-pipelines") 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("yes", "similar")]
+row
+cell The #[strong labrador] swam.
+cell #[code 0.48] #[+procon("no", "dissimilar")]
+row
+cell the #[strong labrador] people live in canada.
+cell #[code 0.39] #[+procon("no", "dissimilar")]
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"Vilnius 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 Vilnius 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 "Vilnius" would still produce very similar results.
+table
- var examples = {"Paris is the largest city in France.": [1, 0.85, 0.65], "Vilnius is the capital of Lithuania.": [0.85, 1, 0.55], "An emu is a large bird.": [0.65, 0.55, 1]}
- var counter = 0
+row
+row
+cell
for _, label in examples
+cell=label
each cells, label in examples
+row(counter ? null : "divider")
+cell=label
for cell in cells
+cell.u-text-center
- var result = cell < 0.7 ? ["no", "dissimilar"] : cell != 1 ? ["yes", "similar"] : ["neutral", "identical"]
| #[code=cell.toFixed(2)] #[+procon(...result)]
- counter++
p
| Sentences that consist of the same words in different order will likely
| be seen as very similar – but never identical.
+code.
docs = [nlp(u"dog bites man"), nlp(u"man bites dog"),
nlp(u"man dog bites"), nlp(u"dog man bites")]
for doc in docs:
for other_doc in docs:
print(doc.similarity(other_doc))
p
| Interestingly, "man bites dog" and "man dog bites" are seen as slightly
| more similar than "man bites dog" and "dog bites man". This may be a
| conincidence – or the result of "man" being interpreted as both sentence's
| subject.
+table
- var examples = {"dog bites man": [1, 0.9, 0.89, 0.92], "man bites dog": [0.9, 1, 0.93, 0.9], "man dog bites": [0.89, 0.93, 1, 0.92], "dog man bites": [0.92, 0.9, 0.92, 1]}
- var counter = 0
+row("head")
+cell
for _, label in examples
+cell.u-text-center=label
each cells, label in examples
+row(counter ? null : "divider")
+cell=label
for cell in cells
+cell.u-text-center
- var result = cell < 0.7 ? ["no", "dissimilar"] : cell != 1 ? ["yes", "similar"] : ["neutral", "identical"]
| #[code=cell.toFixed(2)] #[+procon(...result)]
- counter++

4
website/usage/vectors-similarity.jade
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@ -5,10 +5,6 @@ include ../_includes/_mixins
+section("basics")
include _vectors-similarity/_basics
+section("in-context")
+h(2, "in-context") Similarities in context
include _vectors-similarity/_in-context
+section("custom")
+h(2, "custom") Customising word vectors
include _vectors-similarity/_custom