def initialize(self, corpus, chunks = 100, keepDecomposition = False):
"""
Run SVD decomposition on the corpus. This will define the latent space into
which terms and documents will be mapped.
The SVD is created incrementally, in blocks of `chunks` documents. In the
end, a `self.projection` matrix is constructed that can be used to transform
documents into the latent space. The `U, S, V` decomposition itself is
discarded, unless `keepDecomposition` is True, in which case it is stored
in `self.u`, `self.s` and `self.v`.
The algorithm is adapted from:
**M. Brand. 2006. Fast low-rank modifications of the thin singular value decomposition**
"""
if self.id2word is None:
logging.info("no word id mapping provided; initializing from corpus, assuming identity")
maxId = -1
for document in corpus:
maxId = max(maxId, max([-1] + [fieldId for fieldId, _ in document]))
self.numTerms = 1 + maxId
self.id2word = dict(zip(xrange(self.numTerms), xrange(self.numTerms)))
else:
self.numTerms = 1 + max([-1] + self.id2word.keys())
# initialize decomposition (zero documents so far)
self.u = numpy.matrix(numpy.zeros((self.numTerms, self.numTopics))) # leave default numeric type (=double)
self.s = numpy.matrix(numpy.zeros((self.numTopics, self.numTopics)))
#self.v = numpy.matrix(numpy.zeros((0, self.numTopics)))
self.v = None
# do the actual work -- perform iterative singular value decomposition
# this is done by sequentially updating SVD with `chunks` new documents
chunker = itertools.groupby(enumerate(corpus), key = lambda val: val[0] / chunks)
for chunkNo, (key, group) in enumerate(chunker):
# convert the chunk of documents to vectors
docs = [matutils.doc2vec(doc, self.numTerms) for docNo, doc in group]
# self.svdAddCols(docs, reorth = chunkNo % 100 == 99) # reorthogonalize once in every "100*chunks" documents
self.svdAddCols(docs, reorth = False)
logging.info("processed documents up to #%s" % docNo)
# calculate projection needed to get document-topic matrix from term-document matrix.
#
# the way to represent a vector `x` in latent space is lsi[x] = v = self.s^-1 * self.u^-1 * x,
# so the projection is self.s^-1 * self.u^-1.
#
# the way to compare two documents `x1`, `x2` is to compute v1 * self.s^2 * v2.T, so
# we pre-multiply v * s (ie., scale axes by singular values), and return
# that directly as the representation of `x` in LSI space.
#
# this conveniently simplifies to lsi[x] = self.u.T * x, so the projection is
# just self.u.T
#
# note that neither `v` (the right singular vectors) nor `s` (the singular
# values) are used at all in the transformation
self.projection = self.u.T
if not keepDecomposition:
# once we have the projection stored in self, discard u*s*v decomposition to free up memory
del self.u, self.v
def initialize(self, corpus, chunks = 100, keepDecomposition = False):
"""
Run SVD decomposition on the corpus. This will define the latent space into
which terms and documents will be mapped.
The SVD is created incrementally, in blocks of `chunks` documents. In the
end, a `self.projection` matrix is constructed that can be used to transform
documents into the latent space. The `U, S, V` decomposition itself is
discarded, unless keepDecomposition is True, in which case it is stored
in `self.u`, `self.s` and `self.v`.
The algorithm is adapted from:
M. Brand. 2006. Fast low-rank modifications of the thin singular value decomposition
"""
if self.id2word is None:
logging.info("no word id mapping provided; initializing from corpus, assuming identity")
maxId = -1
for document in corpus:
maxId = max(maxId, max([-1] + [fieldId for fieldId, _ in document]))
self.numTerms = 1 + maxId
self.id2word = dict(zip(xrange(self.numTerms), xrange(self.numTerms)))
else:
self.numTerms = 1 + max([-1] + self.id2word.keys())
# initialize decomposition (zero documents so far)
self.u = numpy.matrix(numpy.zeros((self.numTerms, self.numTopics))) # leave default numeric type (=double)
self.s = numpy.matrix(numpy.zeros((self.numTopics, self.numTopics)))
#self.v = numpy.matrix(numpy.zeros((0, self.numTopics)))
self.v = None
# do the actual work -- perform iterative singular value decomposition
# this is done by sequentially updating SVD with `chunks` new documents
chunker = itertools.groupby(enumerate(corpus), key = lambda val: val[0] / chunks)
for chunkNo, (key, group) in enumerate(chunker):
# convert the chunk of documents to vectors
docs = [matutils.doc2vec(doc, self.numTerms) for docNo, doc in group]
# self.svdAddCols(docs, reorth = chunkNo % 100 == 99) # reorthogonalize once in every "100*chunks" documents
self.svdAddCols(docs, reorth = False)
logging.info("processed documents up to #%s" % docNo)
# calculate projection needed to get document-topic matrix from term-document matrix.
#
# the way to represent a vector `x` in latent space is lsi[x] = v = self.s^-1 * self.u^-1 * x,
# so the projection is self.s^-1 * self.u^-1.
#
# the way to compare two documents `x1`, `x2` is to compute v1 * self.s^2 * v2.T, so
# we pre-multiply v * s (ie., scale axes by singular values), and return
# that directly as the representation of `x` in LSI space.
#
# this conveniently simplifies to lsi[x] = self.u.T * x, so the projection is
# just self.u.T
#
# note that neither `v` (the right singular vectors) nor `s` (the singular
# values) are used at all in the transformation
self.projection = self.u.T
if not keepDecomposition:
# once we have the projection stored in self, discard u*s*v decomposition to free up memory
del self.u, self.v
def __getitem__(self, bow):
"""
Return topic distribution, as a list of (topic_id, topic_value) 2-tuples.
This is done by folding input document into the latent topic space.
"""
vec = matutils.doc2vec(bow, self.numTerms)
vec.shape = (self.numTerms, 1)
topicDist = self.projection * vec
return [(topicId, float(topicValue)) for topicId, topicValue in enumerate(topicDist)
if numpy.isfinite(topicValue) and not numpy.allclose(topicValue, 0.0)]
def __getitem__(self, bow):
"""
Return topic distribution, as a list of (topic_id, topic_value) 2-tuples.
This is done by folding input document into the latent topic space.
"""
vec = matutils.doc2vec(bow, self.numTerms)
vec.shape = (self.numTerms, 1)
topicDist = self.projection * vec
return [(topicId, float(topicValue)) for topicId, topicValue in enumerate(topicDist)
if numpy.isfinite(topicValue) and not numpy.allclose(topicValue, 0.0)]
def testTransform(self):
# create the transformation model
model = ldamodel.LdaModel(self.corpus, numTopics = 2)
# transform one document
doc = list(self.corpus)[0]
transformed = model[doc]
vec = matutils.doc2vec(transformed, 2) # convert to dense vector, for easier equality tests
expected = [0.0, 1.0]
self.assertTrue(numpy.allclose(sorted(vec), sorted(expected))) # must contain the same values, up to re-ordering
def testTransform(self):
# create the transformation model
model = lsimodel.LsiModel(self.corpus, numTopics = 2)
# transform one document
doc = list(self.corpus)[0]
transformed = model[doc]
vec = matutils.doc2vec(transformed, 2) # convert to dense vector, for easier equality tests
expected = [0.1973928, 0.05591352]
self.assertTrue(numpy.allclose(abs(vec), expected)) # transformed entries must be equal up to sign
def initialize(self, corpus, chunks=100, keepDecomposition=False):
"""
Run SVD decomposition on the corpus. This will define the latent space into
which terms and documents will be mapped.
The SVD is created incrementally, in blocks of `chunks` documents.
The algorithm is adapted from:
M. Brand. 2006. Fast low-rank modifications of the thin singular value decomposition
"""
if self.id2word is None:
logging.info(
"no word id mapping provided; initializing from corpus, assuming identity"
)
maxId = -1
for document in corpus:
maxId = max(maxId,
max([-1] + [fieldId for fieldId, _ in document]))
self.numTerms = 1 + maxId
self.id2word = dict(
zip(xrange(self.numTerms), xrange(self.numTerms)))
else:
self.numTerms = 1 + max([-1] + self.id2word.keys())
# initialize decomposition (zero documents so far)
self.u = numpy.matrix(numpy.zeros(
(self.numTerms,
self.numTopics))) # leave default numeric type (=double)
self.s = numpy.matrix(numpy.zeros((self.numTopics, self.numTopics)))
#self.v = numpy.matrix(numpy.zeros((0, self.numTopics)))
self.v = None
# do the actual work -- perform iterative singular value decomposition
# this is done by sequentially updating SVD with `chunks` new documents
chunker = itertools.groupby(enumerate(corpus),
key=lambda val: val[0] / chunks)
for chunkNo, (key, group) in enumerate(chunker):
# convert the chunk of documents to vectors
docs = [
matutils.doc2vec(doc, self.numTerms) for docNo, doc in group
]
# self.svdAddCols(docs, reorth = chunkNo % 100 == 99) # reorthogonalize once in every "100*chunks" documents
self.svdAddCols(docs, reorth=False)
logging.info("processed documents up to #%s" % docNo)
# calculate projection needed to get document-topic matrix from term-document matrix.
# note that v (topics of the training corpus) are not used at all for the transformation
invS = numpy.diag(numpy.diag(1.0 / self.s))
self.projection = numpy.dot(
invS, self.u.T) # s^-1 * u^-1; (k, k) * (k, m) = (k, m)
if keepDecomposition:
# once we have the projection stored in self, discard u*s*v decomposition to free up memory
del self.u, self.s, self.v
def testTransform(self):
# create the transformation model
model = lsimodel.LsiModel(self.corpus, numTopics = 2)
# transform one document
doc = list(self.corpus)[0]
transformed = model[doc]
vec = matutils.doc2vec(transformed, 2) # convert to dense vector, for easier equality tests
expected = numpy.array([-0.6594664, 0.142115444]) # scaled LSI version
# expected = numpy.array([-0.1973928, 0.05591352]) # non-scaled LSI version
self.assertTrue(numpy.allclose(abs(vec), abs(expected))) # transformed entries must be equal up to sign
def initialize(self, corpus, chunks = 100, keepDecomposition = False):
"""
Run SVD decomposition on the corpus. This will define the latent space into
which terms and documents will be mapped.
The SVD is created incrementally, in blocks of `chunks` documents.
The algorithm is adapted from:
M. Brand. 2006. Fast low-rank modifications of the thin singular value decomposition
"""
if self.id2word is None:
logging.info("no word id mapping provided; initializing from corpus, assuming identity")
maxId = -1
for document in corpus:
maxId = max(maxId, max([-1] + [fieldId for fieldId, _ in document]))
self.numTerms = 1 + maxId
self.id2word = dict(zip(xrange(self.numTerms), xrange(self.numTerms)))
else:
self.numTerms = 1 + max([-1] + self.id2word.keys())
# initialize decomposition (zero documents so far)
self.u = numpy.matrix(numpy.zeros((self.numTerms, self.numTopics))) # leave default numeric type (=double)
self.s = numpy.matrix(numpy.zeros((self.numTopics, self.numTopics)))
#self.v = numpy.matrix(numpy.zeros((0, self.numTopics)))
self.v = None
# do the actual work -- perform iterative singular value decomposition
# this is done by sequentially updating SVD with `chunks` new documents
chunker = itertools.groupby(enumerate(corpus), key = lambda val: val[0] / chunks)
for chunkNo, (key, group) in enumerate(chunker):
# convert the chunk of documents to vectors
docs = [matutils.doc2vec(doc, self.numTerms) for docNo, doc in group]
# self.svdAddCols(docs, reorth = chunkNo % 100 == 99) # reorthogonalize once in every "100*chunks" documents
self.svdAddCols(docs, reorth = False)
logging.info("processed documents up to #%s" % docNo)
# calculate projection needed to get document-topic matrix from term-document matrix.
# note that v (topics of the training corpus) are not used at all for the transformation
invS = numpy.diag(numpy.diag(1.0 / self.s))
self.projection = numpy.dot(invS, self.u.T) # s^-1 * u^-1; (k, k) * (k, m) = (k, m)
if keepDecomposition:
# once we have the projection stored in self, discard u*s*v decomposition to free up memory
del self.u, self.s, self.v
def __getitem__(self, bow, scaled = True):
"""
Return latent distribution, as a list of (topic_id, topic_value) 2-tuples.
This is done by folding input document into the latent topic space.
Note that this function returns the latent space representation **scaled by the
singular values**. To return non-scaled embedding, set `scaled` to False.
"""
# if the input vector is in fact a corpus, return a transformed corpus as result
if utils.isCorpus(bow):
return self._apply(bow)
vec = matutils.doc2vec(bow, self.numTerms)
vec.shape = (self.numTerms, 1)
topicDist = self.projection * vec
if not scaled:
topicDist = numpy.diag(numpy.diag(1.0 / self.s)) * topicDist
return [(topicId, float(topicValue)) for topicId, topicValue in enumerate(topicDist)
if numpy.isfinite(topicValue) and not numpy.allclose(topicValue, 0.0)]
def __getitem__(self, bow, scaled = True):
"""
Return latent distribution, as a list of (topic_id, topic_value) 2-tuples.
This is done by folding input document into the latent topic space.
Note that this function returns the latent space representation **scaled by the
singular values**. To return non-scaled embedding, set `scaled` to False.
"""
# if the input vector is in fact a corpus, return a transformed corpus as result
if utils.isCorpus(bow):
return self._apply(bow)
vec = matutils.doc2vec(bow, self.numTerms)
vec.shape = (self.numTerms, 1)
topicDist = self.projection * vec
if not scaled:
topicDist = numpy.diag(numpy.diag(1.0 / self.s)) * topicDist
return [(topicId, float(topicValue)) for topicId, topicValue in enumerate(topicDist)
if numpy.isfinite(topicValue) and not numpy.allclose(topicValue, 0.0)]
