NLP之词向量：利用word2vec对20类新闻文本数据集进行词向量训练、测试(某个单词的相关词汇)
NLP之词向量：利用word2vec对20类新闻文本数据集进行词向量训练、测试(某个单词的相关词汇)
目录
输出结果
设计思路
核心代码
输出结果
寻找训练文本中与morning最相关的10个词汇：
[('afternoon', 0.8329864144325256), ('weekend', 0.7690818309783936), ('evening', 0.7469204068183899),
('saturday', 0.7191835045814514), ('night', 0.7091601490974426), ('friday', 0.6764787435531616),
('sunday', 0.6380082368850708), ('newspaper', 0.6365975737571716), ('summer', 0.6268560290336609),
('season', 0.6137701272964478)]
寻找训练文本中与email最相关的10个词汇：
[('mail', 0.7432783842086792), ('contact', 0.6995242834091187), ('address', 0.6547545194625854),
('replies', 0.6502780318260193), ('mailed', 0.6334187388420105), ('request', 0.6262195110321045),
('sas', 0.6220622658729553), ('send', 0.6207413077354431), ('listserv', 0.617364227771759),
('compuserve', 0.5954489707946777)]
设计思路
核心代码
class Word2Vec(BaseWordEmbeddingsModel):
"""Train, use and evaluate neural networks described in https://code.google.
com/p/word2vec/.
Once you're finished training a model (=no more updates, only querying)
store and use only the :class:`~gensim.models.keyedvectors.KeyedVectors` instance in `self.
wv` to reduce memory.
The model can be stored/loaded via its :meth:`~gensim.models.word2vec.Word2Vec.save`
and
:meth:`~gensim.models.word2vec.Word2Vec.load` methods.
The trained word vectors can also be stored/loaded from a format compatible with the
original word2vec implementation via `self.wv.save_word2vec_format`
and :meth:`gensim.models.keyedvectors.KeyedVectors.load_word2vec_format`.
Some important attributes are the following:
Attributes
----------
wv : :class:`~gensim.models.keyedvectors.Word2VecKeyedVectors`
This object essentially contains the mapping between words and embeddings. After
training, it can be used
directly to query those embeddings in various ways. See the module level docstring for
examples.
vocabulary : :class:'~gensim.models.word2vec.Word2VecVocab'
This object represents the vocabulary (sometimes called Dictionary in gensim) of the
model.
Besides keeping track of all unique words, this object provides extra functionality, such as
constructing a huffman tree (frequent words are closer to the root), or discarding
extremely rare words.
trainables : :class:`~gensim.models.word2vec.Word2VecTrainables`
This object represents the inner shallow neural network used to train the embeddings. The
semantics of the
network differ slightly in the two available training modes (CBOW or SG) but you can think
of it as a NN with
a single projection and hidden layer which we train on the corpus. The weights are then
used as our embeddings
(which means that the size of the hidden layer is equal to the number of features `self.size`).
"""
def __init__(self, sentences=None, size=100, alpha=0.025, window=5, min_count=5,
max_vocab_size=None, sample=1e-3, seed=1, workers=3, min_alpha=0.0001,
sg=0, hs=0, negative=5, ns_exponent=0.75, cbow_mean=1, hashfxn=hash, iter=5,
null_word=0,
trim_rule=None, sorted_vocab=1, batch_words=MAX_WORDS_IN_BATCH,
compute_loss=False, callbacks=(),
max_final_vocab=None):
"""
Parameters
----------
sentences : iterable of iterables, optional
The `sentences` iterable can be simply a list of lists of tokens, but for larger corpora,
consider an iterable that streams the sentences directly from disk/network.
See :class:`~gensim.models.word2vec.BrownCorpus`, :class:`~gensim.models.
word2vec.Text8Corpus`
or :class:`~gensim.models.word2vec.LineSentence` in :mod:`~gensim.models.
word2vec` module for such examples.
See also the `tutorial on data streaming in Python
`_ and the
`gensim demo `_ for examples of
how to use such scores in document classification.
Parameters
----------
sentences : iterable of list of str
The `sentences` iterable can be simply a list of lists of tokens, but for larger corpora,
consider an iterable that streams the sentences directly from disk/network.
See :class:`~gensim.models.word2vec.BrownCorpus`, :class:`~gensim.models.
word2vec.Text8Corpus`
or :class:`~gensim.models.word2vec.LineSentence` in :mod:`~gensim.models.
word2vec` module for such examples.
total_sentences : int, optional
Count of sentences.
chunksize : int, optional
Chunksize of jobs
queue_factor : int, optional
Multiplier for size of queue (number of workers * queue_factor).
report_delay : float, optional
Seconds to wait before reporting progress.
"""
if FAST_VERSION < 0:
warnings.warn("C extension compilation failed, scoring will be slow. "
"Install a C compiler and reinstall gensim for fastness.")
logger.info("scoring sentences with %i workers on %i vocabulary and %i features, "
"using sg=%s hs=%s sample=%s and negative=%s",
self.workers, len(self.wv.vocab), self.trainables.layer1_size, self.sg, self.hs, self.
vocabulary.sample, self.negative)
if not self.wv.vocab:
raise RuntimeError("you must first build vocabulary before scoring new data")
if not self.hs:
raise RuntimeError(
"We have currently only implemented score for the hierarchical softmax scheme, "
"so you need to have run word2vec with hs=1 and negative=0 for this to work.")
def worker_loop():
"""Compute log probability for each sentence, lifting lists of sentences from the jobs
queue."""
work = zeros(1, dtype=REAL) # for sg hs, we actually only need one memory loc
(running sum)
neu1 = matutils.zeros_aligned(self.trainables.layer1_size, dtype=REAL)
while True:
job = job_queue.get()
if job is None: # signal to finish
break
ns = 0
for sentence_id, sentence in job:
if sentence_id >= total_sentences:
break
if self.sg:
score = score_sentence_sg(self, sentence, work)
else:
score = score_sentence_cbow(self, sentence, work, neu1)
sentence_scores[sentence_id] = score
ns += 1
progress_queue.put(ns) # report progress
start, next_report = default_timer(), 1.0 # buffer ahead only a limited number of jobs..
this is the reason we can't simply use ThreadPool :(
job_queue = Queue(maxsize=queue_factor * self.workers)
progress_queue = Queue(maxsize=(queue_factor + 1) * self.workers)
workers = [threading.Thread(target=worker_loop) for _ in xrange(self.workers)]
for thread in workers:
thread.daemon = True # make interrupting the process with ctrl+c easier
thread.start()
sentence_count = 0
sentence_scores = matutils.zeros_aligned(total_sentences, dtype=REAL)
push_done = False
done_jobs = 0
jobs_source = enumerate(utils.grouper(enumerate(sentences), chunksize))
# fill jobs queue with (id, sentence) job items
while True:
try:
job_no, items = next(jobs_source)
if (job_no - 1) * chunksize > total_sentences:
logger.warning("terminating after %i sentences (set higher total_sentences if you
want more).", total_sentences)
job_no -= 1
raise StopIteration()
logger.debug("putting job #%i in the queue", job_no)
job_queue.put(items)
except StopIteration:
logger.info("reached end of input; waiting to finish %i outstanding jobs", job_no -
done_jobs + 1)
for _ in xrange(self.workers):
job_queue.put(None) # give the workers heads up that they can finish -- no more
work!
push_done = True
try:
while done_jobs < (job_no + 1) or not push_done:
ns = progress_queue.get(push_done) # only block after all jobs pushed
sentence_count += ns
done_jobs += 1
elapsed = default_timer() - start
if elapsed >= next_report:
logger.info("PROGRESS: at %.2f%% sentences, %.0f sentences/s", 100.0 *
sentence_count, sentence_count / elapsed)
next_report = elapsed + report_delay # don't flood log, wait report_delay
seconds
else:
break # loop ended by job count; really done
except Empty:
pass # already out of loop; continue to next push
elapsed = default_timer() - start
self.clear_sims()
logger.info("scoring %i sentences took %.1fs, %.0f sentences/s", sentence_count,
elapsed, sentence_count / elapsed)
return sentence_scores[:sentence_count]
def clear_sims(self):
"""Remove all L2-normalized word vectors from the model, to free up memory.
You can recompute them later again using the :meth:`~gensim.models.word2vec.
Word2Vec.init_sims` method.
"""
self.wv.vectors_norm = None
def intersect_word2vec_format(self, fname, lockf=0.0, binary=False, encoding='utf8',
unicode_errors='strict'):
"""Merge in an input-hidden weight matrix loaded from the original C word2vec-tool
format,
where it intersects with the current vocabulary.
No words are added to the existing vocabulary, but intersecting words adopt the file's
weights, and
non-intersecting words are left alone.
Parameters
----------
fname : str
The file path to load the vectors from.
lockf : float, optional
Lock-factor value to be set for any imported word-vectors; the
default value of 0.0 prevents further updating of the vector during subsequent
training. Use 1.0 to allow further training updates of merged vectors.
binary : bool, optional
If True, `fname` is in the binary word2vec C format.
encoding : str, optional
Encoding of `text` for `unicode` function (python2 only).
unicode_errors : str, optional
Error handling behaviour, used as parameter for `unicode` function (python2 only).
"""
overlap_count = 0
logger.info("loading projection weights from %s", fname)
with utils.smart_open(fname) as fin:
header = utils.to_unicode(fin.readline(), encoding=encoding)
vocab_size, vector_size = (int(x) for x in header.split()) # throws for invalid file format
if not vector_size == self.wv.vector_size:
raise ValueError("incompatible vector size %d in file %s" % (vector_size, fname)) #
TOCONSIDER: maybe mismatched vectors still useful enough to merge (truncating/padding)?
if binary:
binary_len = dtype(REAL).itemsize * vector_size
for _ in xrange(vocab_size): # mixed text and binary: read text first, then binary
word = []
while True:
ch = fin.read(1)
if ch == b' ':
break
if ch != b'\n': # ignore newlines in front of words (some binary files have)
word.append(ch)
word = utils.to_unicode(b''.join(word), encoding=encoding,
errors=unicode_errors)
weights = fromstring(fin.read(binary_len), dtype=REAL)
if word in self.wv.vocab:
overlap_count += 1
self.wv.vectors[self.wv.vocab[word].index] = weights
self.trainables.vectors_lockf[self.wv.vocab[word].index] = lockf # lock-factor: 0.0
=no changes
else:
for line_no, line in enumerate(fin):
parts = utils.to_unicode(line.rstrip(), encoding=encoding, errors=unicode_errors).
split(" ")
if len(parts) != vector_size + 1:
raise ValueError("invalid vector on line %s (is this really the text format?)" %
line_no)
word, weights = parts[0], [REAL(x) for x in parts[1:]]
if word in self.wv.vocab:
overlap_count += 1
self.wv.vectors[self.wv.vocab[word].index] = weights
self.trainables.vectors_lockf[self.wv.vocab[word].index] = lockf # lock-factor: 0.0
=no changes
logger.info("merged %d vectors into %s matrix from %s", overlap_count, self.wv.vectors.
shape, fname)
@deprecated("Method will be removed in 4.0.0, use self.wv.__getitem__() instead")
def __getitem__(self, words):
"""Deprecated. Use `self.wv.__getitem__` instead.
Refer to the documentation for :meth:`~gensim.models.keyedvectors.
Word2VecKeyedVectors.__getitem__`.
"""
return self.wv.__getitem__(words)
@deprecated("Method will be removed in 4.0.0, use self.wv.__contains__() instead")
def __contains__(self, word):
"""Deprecated. Use `self.wv.__contains__` instead.
Refer to the documentation for :meth:`~gensim.models.keyedvectors.
Word2VecKeyedVectors.__contains__`.
"""
return self.wv.__contains__(word)
def predict_output_word(self, context_words_list, topn=10):
"""Get the probability distribution of the center word given context words.
Parameters
----------
context_words_list : list of str
List of context words.
topn : int, optional
Return `topn` words and their probabilities.
Returns
-------
list of (str, float)
`topn` length list of tuples of (word, probability).
"""
if not self.negative:
raise RuntimeError(
"We have currently only implemented predict_output_word for the negative
sampling scheme, "
"so you need to have run word2vec with negative > 0 for this to work.")
if not hasattr(self.wv, 'vectors') or not hasattr(self.trainables, 'syn1neg'):
raise RuntimeError("Parameters required for predicting the output words not found.")
word_vocabs = [self.wv.vocab[w] for w in context_words_list if w in self.wv.vocab]
if not word_vocabs:
warnings.warn("All the input context words are out-of-vocabulary for the current
model.")
return None
word2_indices = [word.index for word in word_vocabs]
l1 = np_sum(self.wv.vectors[word2_indices], axis=0)
if word2_indices and self.cbow_mean:
l1 /= len(word2_indices)
# propagate hidden -> output and take softmax to get probabilities
prob_values = exp(dot(l1, self.trainables.syn1neg.T))
prob_values /= sum(prob_values)
top_indices = matutils.argsort(prob_values, topn=topn, reverse=True) # returning the
most probable output words with their probabilities
return [(self.wv.index2word[index1], prob_values[index1]) for index1 in top_indices]
def init_sims(self, replace=False):
"""Deprecated. Use `self.wv.init_sims` instead.
See :meth:`~gensim.models.keyedvectors.Word2VecKeyedVectors.init_sims`.
"""
if replace and hasattr(self.trainables, 'syn1'):
del self.trainables.syn1
return self.wv.init_sims(replace)
def reset_from(self, other_model):
"""Borrow shareable pre-built structures from `other_model` and reset hidden layer
weights.
Structures copied are:
* Vocabulary
* Index to word mapping
* Cumulative frequency table (used for negative sampling)
* Cached corpus length
Useful when testing multiple models on the same corpus in parallel.
Parameters
----------
other_model : :class:`~gensim.models.word2vec.Word2Vec`
Another model to copy the internal structures from.
"""
self.wv.vocab = other_model.wv.vocab
self.wv.index2word = other_model.wv.index2word
self.vocabulary.cum_table = other_model.vocabulary.cum_table
self.corpus_count = other_model.corpus_count
self.trainables.reset_weights(self.hs, self.negative, self.wv)
@staticmethod
def log_accuracy(section):
"""Deprecated. Use `self.wv.log_accuracy` instead.
See :meth:`~gensim.models.word2vec.Word2VecKeyedVectors.log_accuracy`.
"""
return Word2VecKeyedVectors.log_accuracy(section)
@deprecated("Method will be removed in 4.0.0, use self.wv.evaluate_word_analogies()
instead")
def accuracy(self, questions, restrict_vocab=30000, most_similar=None,
case_insensitive=True):
"""Deprecated. Use `self.wv.accuracy` instead.
See :meth:`~gensim.models.word2vec.Word2VecKeyedVectors.accuracy`.
"""
most_similar = most_similar or Word2VecKeyedVectors.most_similar
return self.wv.accuracy(questions, restrict_vocab, most_similar, case_insensitive)
def __str__(self):
"""Human readable representation of the model's state.
Returns
-------
str
Human readable representation of the model's state, including the vocabulary size,
vector size
and learning rate.
"""
return "%s(vocab=%s, size=%s, alpha=%s)" % (
self.__class__.__name__, len(self.wv.index2word), self.wv.vector_size, self.alpha)
def delete_temporary_training_data(self, replace_word_vectors_with_normalized=False):
"""Discard parameters that are used in training and scoring, to save memory.
Warnings
--------
Use only if you're sure you're done training a model.
Parameters
----------
replace_word_vectors_with_normalized : bool, optional
If True, forget the original (not normalized) word vectors and only keep
the L2-normalized word vectors, to save even more memory.
"""
if replace_word_vectors_with_normalized:
self.init_sims(replace=True)
self._minimize_model()
def save(self, *args, **kwargs):
"""Save the model.
This saved model can be loaded again using :func:`~gensim.models.word2vec.
Word2Vec.load`, which supports
online training and getting vectors for vocabulary words.
Parameters
----------
fname : str
Path to the file.
"""
# don't bother storing the cached normalized vectors, recalculable table
kwargs['ignore'] = kwargs.get('ignore', ['vectors_norm', 'cum_table'])
super(Word2Vec, self).save(*args, **kwargs)
def get_latest_training_loss(self):
"""Get current value of the training loss.
Returns
-------
float
Current training loss.
"""
return self.running_training_loss
@deprecated(
"Method will be removed in 4.0.0, keep just_word_vectors = model.wv to retain just the
KeyedVectors instance")
def _minimize_model(self, save_syn1=False, save_syn1neg=False,
save_vectors_lockf=False):
if save_syn1 and save_syn1neg and save_vectors_lockf:
return
if hasattr(self.trainables, 'syn1') and not save_syn1:
del self.trainables.syn1
if hasattr(self.trainables, 'syn1neg') and not save_syn1neg:
del self.trainables.syn1neg
if hasattr(self.trainables, 'vectors_lockf') and not save_vectors_lockf:
del self.trainables.vectors_lockf
self.model_trimmed_post_training = True
@classmethod
def load_word2vec_format(
cls, fname, fvocab=None, binary=False, encoding='utf8', unicode_errors='strict',
limit=None, datatype=REAL):
"""Deprecated. Use :meth:`gensim.models.KeyedVectors.load_word2vec_format`
instead."""
raise DeprecationWarning("Deprecated. Use gensim.models.KeyedVectors.
load_word2vec_format instead.")
def save_word2vec_format(self, fname, fvocab=None, binary=False):
"""Deprecated. Use `model.wv.save_word2vec_format` instead.
See :meth:`gensim.models.KeyedVectors.save_word2vec_format`.
"""
raise DeprecationWarning("Deprecated. Use model.wv.save_word2vec_format instead.")
@classmethod
def load(cls, *args, **kwargs):
"""Load a previously saved :class:`~gensim.models.word2vec.Word2Vec` model.
See Also
--------
:meth:`~gensim.models.word2vec.Word2Vec.save`
Save model.
Parameters
----------
fname : str
Path to the saved file.
Returns
-------
:class:`~gensim.models.word2vec.Word2Vec`
Loaded model.
"""
try:
model = super(Word2Vec, cls).load(*args, **kwargs)
# for backward compatibility for `max_final_vocab` feature
if not hasattr(model, 'max_final_vocab'):
model.max_final_vocab = None
model.vocabulary.max_final_vocab = None
return model
except AttributeError:
logger.info('Model saved using code from earlier Gensim Version. Re-loading old
model in a compatible way.')
from gensim.models.deprecated.word2vec import load_old_word2vec
return load_old_word2vec(*args, **kwargs)