def cossim(vec1, vec2):
vec1, vec2 = dict(vec1), dict(vec2)
if not vec1 or not vec2:
return 0.0
vec1len = 1.0 * math.sqrt(sum(val * val for val in itervalues(vec1)))
vec2len = 1.0 * math.sqrt(sum(val * val for val in itervalues(vec2)))
assert vec1len > 0.0 and vec2len > 0.0, "sparse documents must not contain any explicit zero entries"
if len(vec2) < len(vec1):
vec1, vec2 = vec2, vec1 # swap references so that we iterate over the shorter vector
result = sum(value * vec2.get(index, 0.0) for index, value in iteritems(vec1))
result /= vec1len * vec2len # rescale by vector lengths
return result
def filter_extremes(self, no_below=5, no_above=0.5, keep_n=100000):
"""
Filter out tokens that appear in
1. less than `no_below` documents (absolute number) or
2. more than `no_above` documents (fraction of total corpus size, *not*
absolute number).
3. after (1) and (2), keep only the first `keep_n` most frequent tokens (or
keep all if `None`).
After the pruning, shrink resulting gaps in word ids.
**Note**: Due to the gap shrinking, the same word may have a different
word id before and after the call to this function!
"""
no_above_abs = int(no_above * self.num_docs) # convert fractional threshold to absolute threshold
# determine which tokens to keep
good_ids = (v for v in itervalues(self.token2id)
if no_below <= self.dfs[v] <= no_above_abs)
good_ids = sorted(good_ids, key=self.dfs.get, reverse=True)
if keep_n is not None:
good_ids = good_ids[:keep_n]
logger.info("keeping %i tokens which were in no less than %i and no more than %i (=%.1f%%) documents" %
(len(good_ids), no_below, no_above_abs, 100.0 * no_above))
# do the actual filtering, then rebuild dictionary to remove gaps in ids
self.filter_tokens(good_ids=good_ids)
self.compactify()
logger.info("resulting dictionary: %s" % self)
def filter_extremes(self, no_below=5, no_above=0.5, keep_n=100000):
"""
Filter out tokens that appear in
1. less than `no_below` documents (absolute number) or
2. more than `no_above` documents (fraction of total corpus size, *not*
absolute number).
3. after (1) and (2), keep only the first `keep_n` most frequent tokens (or
keep all if `None`).
After the pruning, shrink resulting gaps in word ids.
**Note**: Due to the gap shrinking, the same word may have a different
word id before and after the call to this function!
"""
no_above_abs = int(
no_above * self.num_docs
) # convert fractional threshold to absolute threshold
# determine which tokens to keep
good_ids = (v for v in itervalues(self.token2id)
if no_below <= self.dfs[v] <= no_above_abs)
good_ids = sorted(good_ids, key=self.dfs.get, reverse=True)
if keep_n is not None:
good_ids = good_ids[:keep_n]
logger.info(
"keeping %i tokens which were in no less than %i and no more than %i (=%.1f%%) documents"
% (len(good_ids), no_below, no_above_abs, 100.0 * no_above))
# do the actual filtering, then rebuild dictionary to remove gaps in ids
self.filter_tokens(good_ids=good_ids)
self.compactify()
logger.info("resulting dictionary: %s" % self)
def create_binary_tree(self):
"""
Create a binary Huffman tree using stored vocabulary word counts. Frequent words
will have shorter binary codes. Called internally from `build_vocab()`.
"""
logger.info("constructing a huffman tree from %i words" % len(self.vocab))
# build the huffman tree
heap = list(itervalues(self.vocab))
heapq.heapify(heap)
for i in xrange(len(self.vocab) - 1):
min1, min2 = heapq.heappop(heap), heapq.heappop(heap)
heapq.heappush(heap, Vocab(count=min1.count + min2.count, index=i + len(self.vocab), left=min1, right=min2))
# recurse over the tree, assigning a binary code to each vocabulary word
if heap:
max_depth, stack = 0, [(heap[0], [], [])]
while stack:
node, codes, points = stack.pop()
if node.index < len(self.vocab):
# leaf node => store its path from the root
node.code, node.point = codes, points
max_depth = max(len(codes), max_depth)
else:
# inner node => continue recursion
points = array(list(points) + [node.index - len(self.vocab)], dtype=uint32)
stack.append((node.left, array(list(codes) + [0], dtype=uint8), points))
stack.append((node.right, array(list(codes) + [1], dtype=uint8), points))
logger.info("built huffman tree with maximum node depth %i" % max_depth)
def sparse2full(doc, length):
"""
Convert a document in sparse corpus format (sequence of 2-tuples) into a dense
numpy array (of size `length`).
"""
result = numpy.zeros(length, dtype=numpy.float32) # fill with zeroes (default value)
doc = dict(doc)
# overwrite some of the zeroes with explicit values
result[list(doc)] = list(itervalues(doc))
return result
def sparse2full(doc, length):
"""
Convert a document in sparse corpus format (sequence of 2-tuples) into a dense
numpy array (of size `length`).
"""
result = numpy.zeros(
length, dtype=numpy.float32) # fill with zeroes (default value)
doc = dict(doc)
# overwrite some of the zeroes with explicit values
result[list(doc)] = list(itervalues(doc))
return result
def create_binary_tree(self):
"""
Create a binary Huffman tree using stored vocabulary word counts. Frequent words
will have shorter binary codes. Called internally from `build_vocab()`.
"""
logger.info("constructing a huffman tree from %i words" %
len(self.vocab))
# build the huffman tree
heap = list(itervalues(self.vocab))
heapq.heapify(heap)
for i in xrange(len(self.vocab) - 1):
min1, min2 = heapq.heappop(heap), heapq.heappop(heap)
heapq.heappush(
heap,
Vocab(count=min1.count + min2.count,
index=i + len(self.vocab),
left=min1,
right=min2))
# recurse over the tree, assigning a binary code to each vocabulary word
if heap:
max_depth, stack = 0, [(heap[0], [], [])]
while stack:
node, codes, points = stack.pop()
if node.index < len(self.vocab):
# leaf node => store its path from the root
node.code, node.point = codes, points
max_depth = max(len(codes), max_depth)
else:
# inner node => continue recursion
points = array(list(points) +
[node.index - len(self.vocab)],
dtype=uint32)
stack.append(
(node.left, array(list(codes) + [0],
dtype=uint8), points))
stack.append(
(node.right, array(list(codes) + [1],
dtype=uint8), points))
logger.info("built huffman tree with maximum node depth %i" %
max_depth)
def compactify(self):
"""
Assign new word ids to all words.
This is done to make the ids more compact, e.g. after some tokens have
been removed via :func:`filter_tokens` and there are gaps in the id series.
Calling this method will remove the gaps.
"""
logger.debug("rebuilding dictionary, shrinking gaps")
# build mapping from old id -> new id
idmap = dict(
izip(itervalues(self.token2id), xrange(len(self.token2id))))
# reassign mappings to new ids
self.token2id = dict((token, idmap[tokenid])
for token, tokenid in iteritems(self.token2id))
self.id2token = {}
self.dfs = dict(
(idmap[tokenid], freq) for tokenid, freq in iteritems(self.dfs))
def compactify(self):
"""
Assign new word ids to all words.
This is done to make the ids more compact, e.g. after some tokens have
been removed via :func:`filter_tokens` and there are gaps in the id series.
Calling this method will remove the gaps.
"""
logger.debug("rebuilding dictionary, shrinking gaps")
# build mapping from old id -> new id
idmap = dict(izip(itervalues(self.token2id),
xrange(len(self.token2id))))
# reassign mappings to new ids
self.token2id = dict((token, idmap[tokenid])
for token, tokenid in iteritems(self.token2id))
self.id2token = {}
self.dfs = dict((idmap[tokenid], freq)
for tokenid, freq in iteritems(self.dfs))
def accuracy(self, questions, restrict_vocab=30000):
"""
Compute accuracy of the model. `questions` is a filename where lines are
4-tuples of words, split into sections by ": SECTION NAME" lines.
See https://code.google.com/p/word2vec/source/browse/trunk/questions-words.txt for an example.
The accuracy is reported (=printed to log and returned as a list) for each
section separately, plus there's one aggregate summary at the end.
Use `restrict_vocab` to ignore all questions containing a word whose frequency
is not in the top-N most frequent words (default top 30,000).
This method corresponds to the `compute-accuracy` script of the original C word2vec.
"""
ok_vocab = dict(sorted(iteritems(self.vocab),
key=lambda item: -item[1].count)[:restrict_vocab])
ok_index = set(v.index for v in itervalues(ok_vocab))
def log_accuracy(section):
correct, incorrect = section['correct'], section['incorrect']
if correct + incorrect > 0:
logger.info("%s: %.1f%% (%i/%i)" %
(section['section'], 100.0 * correct / (correct + incorrect),
correct, correct + incorrect))
sections, section = [], None
for line_no, line in enumerate(open(questions)):
# TODO: use level3 BLAS (=evaluate multiple questions at once), for speed
if line.startswith(': '):
# a new section starts => store the old section
if section:
sections.append(section)
log_accuracy(section)
section = {'section': line.lstrip(': ').strip(), 'correct': 0, 'incorrect': 0}
else:
if not section:
raise ValueError("missing section header before line #%i in %s" % (line_no, questions))
try:
a, b, c, expected = [word.lower() for word in line.split()] # TODO assumes vocabulary preprocessing uses lowercase, too...
except:
logger.info("skipping invalid line #%i in %s" % (line_no, questions))
if a not in ok_vocab or b not in ok_vocab or c not in ok_vocab or expected not in ok_vocab:
logger.debug("skipping line #%i with OOV words: %s" % (line_no, line))
continue
ignore = set(self.vocab[v].index for v in [a, b, c]) # indexes of words to ignore
predicted = None
# find the most likely prediction, ignoring OOV words and input words
for index in argsort(self.most_similar(positive=[b, c], negative=[a], topn=False))[::-1]:
if index in ok_index and index not in ignore:
predicted = self.index2word[index]
if predicted != expected:
logger.debug("%s: expected %s, predicted %s" % (line.strip(), expected, predicted))
break
section['correct' if predicted == expected else 'incorrect'] += 1
if section:
# store the last section, too
sections.append(section)
log_accuracy(section)
total = {'section': 'total', 'correct': sum(s['correct'] for s in sections), 'incorrect': sum(s['incorrect'] for s in sections)}
log_accuracy(total)
sections.append(total)
return sections
def train(self, sentences, total_words=None, word_count=0, chunksize=100):
"""
Update the model's neural weights from a sequence of sentences (can be a once-only generator stream).
Each sentence must be a list of utf8 strings.
"""
if FAST_VERSION < 0:
import warnings
warnings.warn("Cython compilation failed, training will be slow. Do you have Cython installed? `pip install cython`")
logger.info("training model with %i workers on %i vocabulary and %i features" % (self.workers, len(self.vocab), self.layer1_size))
if not self.vocab:
raise RuntimeError("you must first build vocabulary before training the model")
start, next_report = time.time(), [1.0]
word_count, total_words = [word_count], total_words or sum(v.count for v in itervalues(self.vocab))
jobs = Queue(maxsize=2 * self.workers) # buffer ahead only a limited number of jobs.. this is the reason we can't simply use ThreadPool :(
lock = threading.Lock() # for shared state (=number of words trained so far, log reports...)
def worker_train():
"""Train the model, lifting lists of sentences from the jobs queue."""
work = zeros(self.layer1_size, dtype=REAL) # each thread must have its own work memory
neu1 = matutils.zeros_aligned(self.layer1_size, dtype=REAL)
while True:
job = jobs.get()
if job is None: # data finished, exit
break
# update the learning rate before every job
alpha = max(self.min_alpha, self.alpha * (1 - 1.0 * word_count[0] / total_words))
# how many words did we train on? out-of-vocabulary (unknown) words do not count
if self.sg:
job_words = sum(train_sentence_sg(self, sentence, alpha, work) for sentence in job)
else:
job_words = sum(train_sentence_cbow(self, sentence, alpha, work, neu1) for sentence in job)
with lock:
word_count[0] += job_words
elapsed = time.time() - start
if elapsed >= next_report[0]:
logger.info("PROGRESS: at %.2f%% words, alpha %.05f, %.0f words/s" %
(100.0 * word_count[0] / total_words, alpha, word_count[0] / elapsed if elapsed else 0.0))
next_report[0] = elapsed + 1.0 # don't flood the log, wait at least a second between progress reports
workers = [threading.Thread(target=worker_train) for _ in xrange(self.workers)]
for thread in workers:
thread.daemon = True # make interrupting the process with ctrl+c easier
thread.start()
# convert input strings to Vocab objects (or None for OOV words), and start filling the jobs queue
no_oov = ([self.vocab.get(word, None) for word in sentence] for sentence in sentences)
for job_no, job in enumerate(utils.grouper(no_oov, chunksize)):
logger.debug("putting job #%i in the queue, qsize=%i" % (job_no, jobs.qsize()))
jobs.put(job)
logger.info("reached the end of input; waiting to finish %i outstanding jobs" % jobs.qsize())
for _ in xrange(self.workers):
jobs.put(None) # give the workers heads up that they can finish -- no more work!
for thread in workers:
thread.join()
elapsed = time.time() - start
logger.info("training on %i words took %.1fs, %.0f words/s" %
(word_count[0], elapsed, word_count[0] / elapsed if elapsed else 0.0))
return word_count[0]
