def var_bound(data, model, query):
'''
A total nonsense in this case which we retain just so all the other functions
continue to work.
'''
bound = 0
# Unpack the the structs, for ease of access and efficiency
docLens, topicMeans = \
query.docLens, query.topicDists
K, topicPrior, vocabPrior, wordDists, dtype = \
model.K, model.topicPrior, model.vocabPrior, model.wordDists, model.dtype
# Initialize z matrix if necessary
W = data.words
D, T = W.shape
# ln p(x,z) >= sum_k p(z=k|x) * (ln p(x|z=k, phi) + p(z=k)) + H[q]
# Expected joint
like = W.dot(safe_log(wordDists).T) # D*K
like *= safe_log(topicMeans)
# Entropy
ent = (-topicMeans * safe_log(topicMeans)).sum()
return like.sum() + bound
def var_bound(data, model, query):
'''
Determines the variational bounds.
'''
bound = 0
# Unpack the the structs, for ease of access and efficiency
docLens, topicMeans = \
query.docLens, query.topicDists
K, topicPrior, vocabPrior, wordDists, corpusTopicDist, dtype = \
model.K, model.topicPrior, model.vocabPrior, model.wordDists, model.corpusTopicDist, model.dtype
# Initialize z matrix if necessary
W = data.words
D, T = W.shape
# ln p(x,z) >= sum_k p(z=k|x) * (ln p(x|z=k, phi) + p(z=k)) + H[q]
# Expected joint
like = W.dot(safe_log(wordDists).T) # D*K
like += corpusTopicDist[np.newaxis,:]
like *= safe_log(topicMeans)
# Entropy
ent = (-topicMeans * safe_log(topicMeans)).sum()
return like.sum() + bound
def query(data, model, queryState, _):
'''
Infers the topic distributions in general, and specifically for
each individual datapoint, without altering the model
Params:
W - the DxT document-term matrix
X - The DxD document-document matrix
model - the initial model configuration. This is MUTATED IN-PLACE
qyery - the query results - essentially all the "local" variables
matched to the given observations. Also MUTATED IN-PLACE
plan - how to execute the training process (e.g. iterations,
log-interval etc.)
Return:
The updated model object (note parameters are updated in place, so make a
defensive copy if you want it)
The query object with the update query parameters
'''
K, wordDists, corpusTopicDist, topicPrior, vocabPrior = \
model.K, model.wordDists, model.corpusTopicDist, model.topicPrior, model.vocabPrior
topicDists = queryState.topicDists
W = data.words
wordDists = safe_log(wordDists)
corpusTopicDist = safe_log(corpusTopicDist)
topicDists = W.dot(wordDists.T) + corpusTopicDist[np.newaxis, :]
norms = fns.logsumexp(topicDists, axis=1)
topicDists -= norms[:, np.newaxis]
return model, QueryState(queryState.docLens, np.exp(topicDists), True)
def _testInferenceFromHandcraftedExampleWithKEqualingQ(self):
print ("Fully handcrafted example, K=Q")
rd.seed(0xC0FFEE) # Global init for repeatable test
T = 100 # Vocabulary size, the number of "terms". Must be a square number
Q = 6 # Topics: This cannot be changed without changing the code that generates the vocabulary
K = 6 # Observed topics
P = 8 # Features
F = 12 # Observed features
D = 200 # Sample documents (each with associated features)
avgWordsPerDoc = 500
# The vocabulary. Presented graphically there are two with horizontal bands
# (upper lower); two with vertical bands (left, right); and two with
# horizontal bands (inside, outside)
vocab = makeSixTopicVocab(T)
# Create our (sparse) features X, then our topic proportions ("tpcs")
# then our word counts W
lmda = np.zeros((D,K))
X = np.zeros((D,F))
for d in range(D):
for _ in range(3):
lmda[d,rd.randint(K)] += 1./3
for _ in range(int(F/3)):
X[d,rd.randint(F)] += 1
A = rd.random((K,F))
X = lmda.dot(la.pinv(A).T)
X = ssp.csr_matrix(X)
tpcs = lmda
docLens = rd.poisson(avgWordsPerDoc, (D,))
W = tpcs.dot(vocab)
W *= docLens[:, np.newaxis]
W = np.array(W, dtype=np.int32) # truncate word counts to integers
W = ssp.csr_matrix(W)
#
# Now finally try to train the model
#
modelState = newVbModelState(K, Q, F, P, T)
(trainedState, queryState) = train (modelState, X, W, logInterval=1, iterations=1)
tpcs_inf = rowwise_softmax(safe_log(queryState.expLmda))
W_inf = np.array(tpcs_inf.dot(trainedState.vocab) * queryState.docLen[:,np.newaxis], dtype=np.int32)
priorReconsError = np.sum(np.square(W - W_inf)) / D
(trainedState, queryState) = train (modelState, X, W, logInterval=1, plotInterval = 100, iterations=130)
tpcs_inf = rowwise_softmax(safe_log(queryState.expLmda))
W_inf = np.array(tpcs_inf.dot(trainedState.vocab) * queryState.docLen[:,np.newaxis], dtype=np.int32)
print ("Model Driven: Prior Reconstruction Error: %f" % (priorReconsError,))
print ("Model Driven: Final Reconstruction Error: %f" % (np.sum(np.square(W - W_inf)) / D,))
print("End of Test")
def _sparseScalarProductOfSafeLnDot_py(A,B,C, out=None):
'''
Calculates A * B.dot(C) where A is a sparse matrix
Retains sparsity in the result, unlike the built-in operator
Note the type of the return-value is the same as the type of
the sparse matrix A. If this has an integral type, this will
only provide integer-based multiplication.
'''
if WarnIfSlow:
sys.stderr.write("WARNING: Slow code path triggered (_sparseScalarProductOfSafeLnDot_py)")
if not (A.dtype == B.dtype and B.dtype == C.dtype and (out is None or C.dtype == out.dtype)):
raise ValueError ("Inconsistent dtypes in the three matrices and possibly the out-param")
if out is None:
out = A.copy()
else:
out.data[:] = A.data
rhs = B.dot(C)
rhs[rhs < sys.float_info.min] = sys.float_info.min
out.data *= safe_log(rhs)[csr_indices(out.indptr, out.indices)]
return out
def sample_memberships(W, alpha, wordDists, memberships):
_, K = memberships.shape
priorNum = memberships.sum(axis=0) + alpha - 1
prior = priorNum.copy()
sample_dists = W.dot(safe_log(wordDists).T) # d x k
for d in range(W.shape[0]):
priorNum -= memberships[d, :]
prior[:] = priorNum
prior /= priorNum.sum()
sample_dists[d, :] += safe_log(prior)
sample_dists[d, :] -= sample_dists[d, :].max()
sample_dists[d, :] -= fns.logsumexp(sample_dists[d, :])
np.exp(sample_dists[d, :], out=sample_dists[d, :])
memberships[d, :] = rd.multinomial(1, sample_dists[d, :], size=1)
priorNum += memberships[d, :]
return memberships
def iterate (iterations, D, K, T, \
W_list, docLens, \
topicPrior, vocabPrior, \
z_dnk, topicDists, wordDists):
raise ValueError("This implementation no longer supported")
totalItrs = 0
epsilon = 0.01 / K
oldWordDists = np.empty(wordDists.shape, wordDists.dtype)
newWordDists = wordDists
for _ in range(iterations):
oldWordDists, newWordDists = newWordDists, oldWordDists
lnWordDists = safe_log(oldWordDists, out=oldWordDists)
newWordDists.fill (vocabPrior)
for d in range(D):
oldTopics = topicDists[d,:].copy()
topicDists[d,:]= 1./ K
lnWordProbs = lnWordDists[:,W_list[d,0:docLens[d]]]
innerItrs = 0
while ((innerItrs < MaxInnerItrs) or (np.sum(np.abs(oldTopics - topicDists[d,:])) > epsilon)) \
and (innerItrs < MaxInnerItrs):
diTopic = fns.digamma(topicDists[d,:])
z_dnk[:docLens[d],:] = lnWordProbs.T + diTopic[np.newaxis,:]
# We've been working in log-space till now, before we go to true
# probability space rescale so we don't underflow everywhere
maxes = z_dnk.max(axis=1)
z_dnk -= maxes[:,np.newaxis]
np.exp(z_dnk, out=z_dnk)
# Now normalize so probabilities sum to one
sums = z_dnk.sum(axis=1)
z_dnk /= sums[:,np.newaxis] # Update vocabulary: hard to do with a list representation
# Now use it to infer the topic distribution
topicDists[d,:] = topicPrior + np.sum(z_dnk[:docLens[d],:], axis=0)
topicDists[d,:] /= np.sum(topicDists[d,:])
innerItrs += 1
totalItrs += innerItrs
for k in range(K):
for n in range(docLens[d]):
newWordDists[k,W_list[d,n]] += z_dnk[n,k]
newWordDists /= newWordDists.sum(axis=1)[:,np.newaxis]
return totalItrs
def varBound(modelState, queryState, X, W, lnVocab=None, XAT=None, XTX=None, scaledWordCounts=None, VTV=None, UTU=None):
#
# TODO Standardise hyperparameter handling so we can eliminate this copy and paste
#
# Unpack the model and query state tuples for ease of use and maybe speed improvements
K, Q, F, P, T, A, varA, Y, omY, sigY, sigT, U, V, vocab, _, alphaSq, kappaSq, tauSq = (
modelState.K,
modelState.Q,
modelState.F,
modelState.P,
modelState.T,
modelState.A,
modelState.varA,
modelState.Y,
modelState.omY,
modelState.sigY,
modelState.sigT,
modelState.U,
modelState.V,
modelState.vocab,
modelState.topicVar,
modelState.featVar,
modelState.lowTopicVar,
modelState.lowFeatVar,
)
(expLmda, nu, lxi, s, docLen) = (queryState.expLmda, queryState.nu, queryState.lxi, queryState.s, queryState.docLen)
lmda = np.log(expLmda)
isigT = la.inv(sigT)
lnDetSigT = la.det(sigT)
sigmaSq = 1 # A bit of a hack till hyperparameter handling is standardised
# Get the number of samples from the shape. Ensure that the shapes are consistent
# with the model parameters.
(D, Tcheck) = W.shape
if Tcheck != T:
raise ValueError(
"The shape of the DxT document matrix W is invalid, T is %d but the matrix W has shape (%d, %d)"
% (T, D, Tcheck)
)
(Dcheck, Fcheck) = X.shape
if Dcheck != D:
raise ValueError("Inconsistent sizes between the matrices X and W, X has %d rows but W has %d" % (Dcheck, D))
if Fcheck != F:
raise ValueError(
"The shape of the DxF feature matrix X is invalid. F is %d but the matrix X has shape (%d, %d)"
% (F, Dcheck, Fcheck)
)
# We'll need the original xi for this and also Z, the 3D tensor of which for each document D
# and term T gives the strength of topic K. We'll also need the log of the vocab dist
xi = deriveXi(lmda, nu, s)
# If not already provided, we'll also need the following products
#
if XAT is None:
XAT = X.dot(A.T)
if XTX is None:
XTX = X.T.dot(X)
if V is not None and VTV is None:
VTV = V.T.dot(V)
if U is not None and UTU is None:
UTU = U.T.dot(U)
# also need one over the usual variances
overSsq, overAsq, overKsq, overTsq = 1.0 / sigmaSq, 1.0 / alphaSq, 1.0 / kappaSq, 1.0 / tauSq
overTkSq = overTsq * overKsq
overAsSq = overAsq * overSsq
# <ln p(Y)>
#
trSigY = 1 if sigY is None else np.trace(sigY)
trOmY = K # Basically it's the trace of the identity matrix as the posterior and prior cancel out
lnP_Y = -0.5 * (
Q * P * LOG_2PI + P * lnDetSigT + overTkSq * trSigY * trOmY + overTkSq * np.trace(isigT.dot(Y).dot(Y.T))
)
# <ln P(A|Y)>
# TODO it looks like I should take the trace of omA \otimes I_K here.
# TODO Need to check re-arranging sigY and omY is sensible.
halfKF = 0.5 * K * F
# Horrible, but varBound can be called by two implementations, one with Y as a matrix-variate
# where sigY is QxQ and one with Y as a multi-varate, where sigY is a QPxQP.
A_from_Y = Y.dot(U.T) if V is None else U.dot(Y).dot(V.T)
A_diff = A - A_from_Y
varFactorU = np.trace(sigY.dot(np.kron(VTV, UTU))) if sigY.shape[0] == Q * P else np.sum(sigY * UTU)
varFactorV = 1 if V is None else np.sum(omY * V.T.dot(V))
lnP_A = (
-halfKF * LOG_2PI
- halfKF * log(alphaSq)
- F / 2.0 * lnDetSigT
- 0.5 * (overAsSq * varFactorV * varFactorU + np.trace(XTX.dot(varA)) * K + np.sum(isigT.dot(A_diff) * A_diff))
)
# <ln p(Theta|A,X)
#
lmdaDiff = lmda - XAT
lnP_Theta = (
-0.5 * D * LOG_2PI
- 0.5 * D * lnDetSigT
- 0.5 / sigmaSq * (np.sum(nu) + D * K * np.sum(XTX * varA) + np.sum(lmdaDiff.dot(isigT) * lmdaDiff))
)
# Why is order of sigT reversed? It's 'cause we've not been consistent. A is KxF but lmda is DxK, and
# note that the distribution of lmda transpose has the same covariances, just in different positions
# (i.e. row is col and vice-versa)
# <ln p(Z|Theta)
#
docLenLmdaLxi = docLen[:, np.newaxis] * lmda * lxi
scaledWordCounts = sparseScalarQuotientOfDot(W, expLmda, vocab, out=scaledWordCounts)
lnP_Z = 0.0
lnP_Z -= np.sum(docLenLmdaLxi * lmda)
lnP_Z -= np.sum(docLen[:, np.newaxis] * nu * nu * lxi)
lnP_Z += 2 * np.sum(s[:, np.newaxis] * docLenLmdaLxi)
lnP_Z -= 0.5 * np.sum(docLen[:, np.newaxis] * lmda)
lnP_Z += np.sum(
lmda * expLmda * (scaledWordCounts.dot(vocab.T))
) # n(d,k) = expLmda * (scaledWordCounts.dot(vocab.T))
lnP_Z -= np.sum(docLen[:, np.newaxis] * lxi * ((s ** 2)[:, np.newaxis] - xi ** 2))
lnP_Z += 0.5 * np.sum(docLen[:, np.newaxis] * (s[:, np.newaxis] + xi))
lnP_Z -= np.sum(docLen[:, np.newaxis] * safe_log_one_plus_exp_of(xi))
lnP_Z -= np.sum(docLen * s)
# <ln p(W|Z, vocab)>
#
lnP_w_dt = sparseScalarProductOfDot(scaledWordCounts, expLmda, vocab * safe_log(vocab))
lnP_W = np.sum(lnP_w_dt.data)
# H[q(Y)]
lnDetOmY = 0 if omY is None else log(la.det(omY))
lnDetSigY = 0 if sigY is None else log(max(la.det(sigY), sys.float_info.min)) # TODO FIX THIS
ent_Y = 0.5 * (P * K * LOG_2PI_E + Q * lnDetOmY + P * lnDetSigY)
# H[q(A|Y)]
#
# A few things - omA is fixed so long as tau and sigma are, so there's no benefit in
# recalculating this every time.
#
# However in a recent test, la.det(omA) = 0
# this is very strange as omA is the inverse of (s*I + t*XTX)
#
# ent_A = 0.5 * (F * K * LOG_2PI_E + K * log (la.det(omA)) + F * K * log (tau2))\
ent_A = 0
# H[q(Theta|A)]
ent_Theta = 0.5 * (K * LOG_2PI_E + np.sum(np.log(nu * nu)))
# H[q(Z|\Theta)
#
# So Z_dtk \propto expLmda_dt * vocab_tk. We let N here be the normalizer (which is
# \sum_j expLmda_dt * vocab_tj, which implies N is DxT. We need to evaluate
# Z_dtk * log Z_dtk. We can pull out the normalizer of the first term, but it has
# to stay in the log Z_dtk expression, hence the third term in the sum. We can however
# take advantage of the ability to mix dot and element-wise products for the different
# components of Z_dtk in that three-term sum, which we denote as S
# Finally we use np.sum to sum over d and t
#
ent_Z = 0 # entropyOfDot(expLmda, vocab)
result = lnP_Y + lnP_A + lnP_Theta + lnP_Z + lnP_W + ent_Y + ent_A + ent_Theta + ent_Z
return result
def var_bound(data, modelState, queryState):
'''
Determines the variational bounds. Values are mutated in place, but are
reset afterwards to their initial values. So it's safe to call in a serial
manner.
'''
# Unpack the the structs, for ease of access and efficiency
W, L, X = data.words, data.links, data.feats
D,_ = W.shape
outMeans, outVarcs, inMeans, inVarcs, inDocCov, docLens = queryState.outMeans, queryState.outVarcs, queryState.inMeans, queryState.inVarcs, queryState.inDocCov, queryState.docLens
K, topicMean, topicCov, outDocCov, vocab, A, dtype = modelState.K, modelState.topicMean, modelState.topicCov, modelState.outDocCov, modelState.vocab, modelState.A, modelState.dtype
# Calculate some implicit variables
itopicCov = la.inv(topicCov)
bound = 0
expMeansOut = np.exp(outMeans - outMeans.max(axis=1)[:, np.newaxis])
expMeansIn = np.exp(inMeans - inMeans.max(axis=0)[np.newaxis, :])
lse_at_k = expMeansIn.sum(axis=0)
# Distribution over document topics
bound -= (D*K)/2. * LN_OF_2_PI
bound -= D/2. * safe_log_det(outDocCov * topicCov)
diff = outMeans - topicMean[np.newaxis,:]
bound -= 0.5 * np.sum (diff.dot(itopicCov) * diff * 1./outDocCov)
bound -= (0.5 / outDocCov) * np.sum(outVarcs * np.diag(itopicCov)[np.newaxis,:]) # = -0.5 * sum_d tr(V_d \Sigma^{-1}) when V_d is diagonal only.
# And its entropy
bound += 0.5 * D * K * LN_OF_2_PI_E + 0.5 * np.log(outVarcs).sum()
# Distribution over document in-links
inDocPre = np.reciprocal(inDocCov)
bound -= (D*K)/2. * LN_OF_2_PI
bound -= D/2. * safe_log_det(topicCov)
bound -= K/2 * safe_log(inDocCov).sum()
diff = inMeans - outMeans
bound -= 0.5 * np.sum (diff.dot(itopicCov) * diff * inDocPre[:,np.newaxis])
bound -= 0.5 * np.sum((inVarcs * inDocPre[:,np.newaxis]) * np.diag(itopicCov)[np.newaxis,:]) # = -0.5 * sum_d tr(V_d \Sigma^{-1}) when V_d is diagonal only.
# And its entropy
bound += 0.5 * D * K * LN_OF_2_PI_E + 0.5 * np.log(inVarcs).sum()
# Distribution over topic assignments E[p(Z)] and E[p(Y)]
W_weights = sparseScalarQuotientOfDot(W, expMeansOut, vocab) # D x V [W / TB] is the quotient of the original over the reconstructed doc-term matrix
top_sums = expMeansOut * (W_weights.dot(vocab.T)) # D x K
L_weights = sparseScalarQuotientOfNormedDot(L, expMeansOut, expMeansIn, lse_at_k)
top_sums += expMeansOut * (L_weights.dot(expMeansIn) / lse_at_k[np.newaxis, :])
# E[p(Z,Y)]
linkLens = np.squeeze(np.array(L.sum(axis=1)))
bound += np.sum(outMeans * top_sums)
bound -= np.sum((docLens + linkLens) * np.log(np.sum(expMeansOut, axis=1)))
# H[Z]
bound += ((W_weights.dot(vocab.T)) * expMeansOut * outMeans).sum() \
+ ((W_weights.dot((np.log(vocab) * vocab).T)) * expMeansOut).sum() \
- np.trace(sparseScalarProductOfSafeLnDot(W_weights, expMeansOut, vocab).dot(vocab.T).dot(expMeansOut.T))
# H[Y]
docVocab = (expMeansIn / lse_at_k[np.newaxis,:]).T.copy()
bound += ((L_weights.dot(docVocab.T)) * expMeansOut * outMeans).sum() \
+ ((L_weights.dot((np.log(docVocab) * docVocab).T)) * expMeansOut).sum() \
- np.trace(sparseScalarProductOfSafeLnDot(L_weights, expMeansOut, docVocab).dot(docVocab.T).dot(expMeansOut.T))
# E[p(W)]
vlv = np.log(vocab) * vocab
bound += np.trace(expMeansOut.T.dot(W_weights.dot(vlv.T)))
# E[p(L)
dld = np.log(docVocab) * docVocab
bound += np.trace(expMeansOut.T.dot(L_weights.dot(dld.T)))
return bound
def var_bound(data, modelState, queryState, z_dnk = None):
'''
Determines the variational bounds.
'''
# Unpack the the structs, for ease of access and efficiency
W_list, docLens, topicDists = \
queryState.W_list, queryState.docLens, queryState.topicDists
K, topicPrior, vocabPrior, _, dtype = \
modelState.K, modelState.topicPrior, modelState.vocabPrior, modelState.wordDists, modelState.dtype
W = data.words
D,T = W.shape
maxN = docLens.max()
if z_dnk == None:
z_dnk = np.empty(shape=(maxN, K), dtype=dtype)
wordDistsMatrix = wordDists(modelState)
diWordDists = fns.digamma(wordDistsMatrix.copy()) - fns.digamma(wordDistsMatrix.sum(axis=1))[:,np.newaxis]
lnWordDists = np.log(wordDistsMatrix)
bound = 0
# Expected Probablity
#
# P(topics|topicPrior)
diTopicDists = fns.digamma(topicDists) - fns.digamma(topicDists.sum(axis=1))[:,np.newaxis]
ln_b_topic = fns.gammaln(topicPrior.sum()) - fns.gammaln(topicPrior).sum()
bound += D * ln_b_topic \
+ np.sum((topicPrior - 1) * diTopicDists)
# and its entropy
ent = fns.gammaln(topicDists.sum(axis=1)).sum() - fns.gammaln(topicDists).sum() \
+ np.sum ((topicDists - 1) * diTopicDists)
bound -= ent
# P(z|topic) is tricky as we don't actually store this. However
# we make a single, simple estimate for this case.
# NOTE COPY AND PASTED FROM iterate_f32 / iterate_f64 (-ish)
for d in range(D):
lnWordProbs = lnWordDists[:,W_list[d,0:docLens[d]]]
diTopic = fns.digamma(topicDists[d,:])
z_dnk[0:docLens[d],:] = lnWordProbs.T + diTopic[np.newaxis,:]
# We've been working in log-space till now, before we go to true
# probability space rescale so we don't underflow everywhere
maxes = z_dnk.max(axis=1)
z_dnk -= maxes[:,np.newaxis]
np.exp(z_dnk, out=z_dnk)
# Now normalize so probabilities sum to one
sums = z_dnk.sum(axis=1)
z_dnk /= sums[:,np.newaxis]
# z_dnk[docLens[d]:maxN,:] = 0 # zero probablities for words that don't exist
# Now use to calculate E[ln p(Z|topics), E[ln p(W|Z) and H[Z] in that order
diTopic -= fns.digamma(np.sum(topicDists[d,:]))
bound += np.sum(z_dnk * diTopic[np.newaxis,:])
bound += np.sum(z_dnk[0:docLens[d],:].T * diWordDists[:,W_list[d,0:docLens[d]]])
bound -= np.sum(z_dnk[0:docLens[d],:] * safe_log(z_dnk[0:docLens[d],:]))
# p(vocabDists|vocabPrior)
ln_b_vocab = fns.gammaln(T * vocabPrior) - T * fns.gammaln(vocabPrior)
bound += K * ln_b_vocab \
+ (vocabPrior - 1) * np.sum(diWordDists)
# and its entropy
ent = fns.gammaln(wordDistsMatrix.sum(axis=1)).sum() - fns.gammaln(wordDistsMatrix).sum() \
+ np.sum ((wordDistsMatrix - 1) * diWordDists)
bound -= ent
return bound
def _testInferenceFromHandcraftedExampleWithKEqualingQ(self):
print("Fully handcrafted example, K=Q")
rd.seed(0xC0FFEE) # Global init for repeatable test
T = 100 # Vocabulary size, the number of "terms". Must be a square number
Q = 6 # Topics: This cannot be changed without changing the code that generates the vocabulary
K = 6 # Observed topics
P = 8 # Features
F = 12 # Observed features
D = 200 # Sample documents (each with associated features)
avgWordsPerDoc = 500
# The vocabulary. Presented graphically there are two with horizontal bands
# (upper lower); two with vertical bands (left, right); and two with
# horizontal bands (inside, outside)
vocab = makeSixTopicVocab(T)
# Create our (sparse) features X, then our topic proportions ("tpcs")
# then our word counts W
lmda = np.zeros((D, K))
X = np.zeros((D, F))
for d in range(D):
for _ in range(3):
lmda[d, rd.randint(K)] += 1. / 3
for _ in range(int(F / 3)):
X[d, rd.randint(F)] += 1
A = rd.random((K, F))
X = lmda.dot(la.pinv(A).T)
X = ssp.csr_matrix(X)
tpcs = lmda
docLens = rd.poisson(avgWordsPerDoc, (D, ))
W = tpcs.dot(vocab)
W *= docLens[:, np.newaxis]
W = np.array(W, dtype=np.int32) # truncate word counts to integers
W = ssp.csr_matrix(W)
#
# Now finally try to train the model
#
modelState = newVbModelState(K, Q, F, P, T)
(trainedState, queryState) = train(modelState,
X,
W,
logInterval=1,
iterations=1)
tpcs_inf = rowwise_softmax(safe_log(queryState.expLmda))
W_inf = np.array(tpcs_inf.dot(trainedState.vocab) *
queryState.docLen[:, np.newaxis],
dtype=np.int32)
priorReconsError = np.sum(np.square(W - W_inf)) / D
(trainedState, queryState) = train(modelState,
X,
W,
logInterval=1,
plotInterval=100,
iterations=130)
tpcs_inf = rowwise_softmax(safe_log(queryState.expLmda))
W_inf = np.array(tpcs_inf.dot(trainedState.vocab) *
queryState.docLen[:, np.newaxis],
dtype=np.int32)
print("Model Driven: Prior Reconstruction Error: %f" %
(priorReconsError, ))
print("Model Driven: Final Reconstruction Error: %f" %
(np.sum(np.square(W - W_inf)) / D, ))
print("End of Test")
def var_bound(data, model, query, z_dnk = None):
'''
Determines the variational bounds.
'''
bound = 0
# Unpack the the structs, for ease of access and efficiency
K, topicPrior, wordPrior, wordDists, weights, negCount, reg, dtype = \
model.K, model.topicPrior, model.vocabPrior, model.wordDists, model.weights, model.pseudoNegCount, model.regularizer, model.dtype
docLens, topicDists = \
query.docLens, query.topicDists
W,X = data.words, data.links
D,T = W.shape
minNonZero = 1E-300 if dtype is np.float64 else 1E-30
# Perform the digamma transform for E[ln \theta] etc.
topicDists = topicDists.copy()
diTopicDists = fns.digamma(topicDists[:, :K])
diSumTopicDists = fns.digamma(topicDists[:, :K].sum(axis=1))
diWordDists = fns.digamma(model.wordDists)
diSumWordDists = fns.digamma(model.wordDists.sum(axis=1))
# E[ln p(topics|topicPrior)] according to q(topics)
#
prob_topics = D * (fns.gammaln(topicPrior[:K].sum()) - fns.gammaln(topicPrior[:K]).sum()) \
+ np.sum((topicPrior[:K] - 1)[np.newaxis, :] * (diTopicDists - diSumTopicDists[:, np.newaxis]))
bound += prob_topics
# and its entropy
ent_topics = _dirichletEntropy(topicDists[:, :K])
bound += ent_topics
# E[ln p(vocabs|vocabPrior)]
#
if type(model.vocabPrior) is float or type(model.vocabPrior) is int:
prob_vocabs = K * (fns.gammaln(wordPrior * T) - T * fns.gammaln(wordPrior)) \
+ np.sum((wordPrior - 1) * (diWordDists - diSumWordDists[:,np.newaxis] ))
else:
prob_vocabs = K * (fns.gammaln(wordPrior.sum()) - fns.gammaln(wordPrior).sum()) \
+ np.sum((wordPrior - 1)[np.newaxis,:] * (diWordDists - diSumWordDists[:,np.newaxis] ))
bound += prob_vocabs
# and its entropy
ent_vocabs = _dirichletEntropy(wordDists)
bound += ent_vocabs
# P(z|topic) is tricky as we don't actually store this. However
# we make a single, simple estimate for this case.
topicMeans = _convertDirichletParamToMeans(docLens, topicDists, topicPrior)
prob_words = 0
prob_z = 0
ent_z = 0
for d in range(D):
wordIdx, z = _infer_topics_at_d(d, data, weights, docLens, topicMeans, topicPrior, diWordDists, diSumWordDists)
# E[ln p(Z|topics) = sum_d sum_n sum_k E[z_dnk] E[ln topicDist_dk]
exLnTopic = diTopicDists[d, :K] - diSumTopicDists[d]
prob_z += np.dot(z * exLnTopic[:, np.newaxis], W[d, :].data).sum()
# E[ln p(W|Z)] = sum_d sum_n sum_k sum_t E[z_dnk] w_dnt E[ln vocab_kt]
prob_words += np.sum(W[d, :].data[np.newaxis, :] * z * (diWordDists[:, wordIdx] - diSumWordDists[:, np.newaxis]))
# And finally the entropy of Z
ent_z -= np.dot(z * safe_log(z), W[d, :].data).sum()
bound += (prob_z + ent_z + prob_words)
# Next, the distribution over links - we just focus on the positives in this case
for d in range(D):
links = _links_up_to(d, X)
if len(links) == 0:
continue
scores = topicMeans[links, :].dot(weights * topicMeans[d])
probs = _probit_inplace(scores) + minNonZero
lnProbs = np.log(probs, out=probs)
# expected probability of all links from d to p < d such that y_dp = 1
bound += lnProbs.sum()
_convertMeansToDirichletParam(docLens, topicMeans, topicPrior)
return bound
def var_bound(data, model, query, z_dnk = None):
'''
Determines the variational bounds.
'''
bound = 0
# Unpack the the structs, for ease of access and efficiency
K, topicPrior, wordPrior, wordDists, dtype = \
model.K, model.topicPrior, model.vocabPrior, model.wordDists, model.dtype
docLens, topicDists = \
query.docLens, query.topicDists
# Initialize z matrix if necessary
W,X = data.words, data.links
D,T = W.shape
# Perform the digamma transform for E[ln \theta] etc.
topicDists = topicDists.copy()
diTopicDists = fns.digamma(topicDists)
diSumTopicDists = fns.digamma(topicDists.sum(axis=1))
diWordDists = fns.digamma(model.wordDists)
diSumWordDists = fns.digamma(model.wordDists.sum(axis=1))
# E[ln p(topics|topicPrior)] according to q(topics)
#
prob_topics = D * (fns.gammaln(topicPrior.sum()) - fns.gammaln(topicPrior).sum()) \
+ np.sum((topicPrior - 1)[np.newaxis, :] * (diTopicDists - diSumTopicDists[:, np.newaxis]))
bound += prob_topics
# and its entropy
ent_topics = _dirichletEntropy(topicDists)
bound += ent_topics
# E[ln p(vocabs|vocabPrior)]
#
if type(model.vocabPrior) is float or type(model.vocabPrior) is int:
prob_vocabs = K * (fns.gammaln(wordPrior * T) - T * fns.gammaln(wordPrior)) \
+ np.sum((wordPrior - 1) * (diWordDists - diSumWordDists[:, np.newaxis] ))
else:
prob_vocabs = K * (fns.gammaln(wordPrior.sum()) - fns.gammaln(wordPrior).sum()) \
+ np.sum((wordPrior - 1)[np.newaxis,:] * (diWordDists - diSumWordDists[:, np.newaxis] ))
bound += prob_vocabs
# and its entropy
ent_vocabs = _dirichletEntropy(wordDists)
bound += ent_vocabs
# P(z|topic) is tricky as we don't actually store this. However
# we make a single, simple estimate for this case.
topicMeans = _convertDirichletParamToMeans(docLens, topicDists, topicPrior)
prob_words = 0
prob_z = 0
ent_z = 0
for d in range(D):
wordIdx, z = _infer_topics_at_d(d, data, docLens, topicMeans, topicPrior, diWordDists, diSumWordDists)
# E[ln p(Z|topics) = sum_d sum_n sum_k E[z_dnk] E[ln topicDist_dk]
exLnTopic = diTopicDists[d, :] - diSumTopicDists[d]
prob_z += np.dot(z * exLnTopic[:, np.newaxis], W[d, :].data).sum()
# E[ln p(W|Z)] = sum_d sum_n sum_k sum_t E[z_dnk] w_dnt E[ln vocab_kt]
prob_words += np.sum(W[d, :].data[np.newaxis, :] * z * (diWordDists[:, wordIdx] - diSumWordDists[:, np.newaxis]))
# And finally the entropy of Z
ent_z -= np.dot(z * safe_log(z), W[d, :].data).sum()
bound += (prob_z + ent_z + prob_words)
_convertMeansToDirichletParam(docLens, topicMeans, topicPrior)
return bound
def var_bound(data, model, query, z_dnk = None):
'''
Determines the variational bounds.
'''
bound = 0
# Unpack the the structs, for ease of access and efficiency
docLens, topics, postTopicCov, U, V, tsums_bydoc, tsums_bytop, exp_tsums_bydoc, exp_tsums_bytop, lse_at_k, out_counts, in_counts = \
query.docLens, query.topics, query.postTopicCov, query.U, query.V, query.tsums_bydoc, query.tsums_bytop, query.exp_tsums_bydoc, query.exp_tsums_bytop, query.lse_at_k, query.out_counts, query.in_counts
K, Q, topicPrior, vocabPrior, wordDists, topicCov, dtype, name = \
model.K, model.Q, model.topicPrior, model.vocabPrior, model.wordDists, model.topicCov, model.dtype, model.name
W, L = data.words, data.links
D, T = W.shape
bound = 0
# Pre-calculate some repeated expressinos
logVagueness = log(Vagueness)
halfDQ, halfQK, halfDK = 0.5*D*Q, 0.5*Q*K, 0.5*D*K
logTwoPi = log(2 * pi)
logTwoPiE = log(2 * pi * e)
# # E[ln p(U)]
# bound += -halfDQ * logTwoPi - D * Q * logVagueness - 0.5 * np.sum(U * U) # trace of U U'
#
# # H[q(U)]
# bound += -halfDQ * logTwoPiE - D * Q * logVagueness
#
# # E[ln p(V)]
# bound += -halfQK * logTwoPi - Q * K * logVagueness - 0.5 * np.sum(V * V) # trace of U U'
#
# # H[q(V)]
# bound += -halfQK * logTwoPiE - D * Q * logVagueness
# ln p(Topics|U, V)
logDetCov = log(la.det(topicCov))
kernel = topics.copy()
kernel -= U.dot(V)
kernel **= 2
kernel[:] = kernel.dot(topicCov)
kernel /= (2 * Vagueness)
bound += -halfDK * logTwoPi - halfDK * logVagueness \
-D * 0.5 * logDetCov \
-np.sum(kernel) \
-np.sum(postTopicCov)
# FIXME bound here is squiffy
# H[q(topics)]
bound += -halfDK * logTwoPiE - halfDK * logVagueness - D * 0.5 * logDetCov
# We'll need these for the next steps
diWordDists = fns.digamma(wordDists)
diWordDistSums = fns.digamma(wordDists.sum(axis=1))
# P(z|topic) and P(y|topic) are not stored explicitly, so we need to
# recalculate here to calculate their expected log-probs and entropies.
prob_words, prob_links = 0, 0
prob_z, ent_z = 0, 0
prob_y, ent_y = 0, 0
for d in range(D):
# First the word-topic assignments, note this is a KxV matrix
wordIdx, z = _infer_word_topics_at_d(d, W, topics, diWordDists, diWordDistSums)
# E[ln p(Z|topics) = sum_d sum_n sum_k E[z_dnk] E[ln topicDist_dk]
prob_z += topics[d, :].dot(z * W[d, :].data[np.newaxis, :]).sum()
prob_z -= docLens[d] * lse(topics[d, :])
# E[ln p(W|Z)] = sum_d sum_n sum_k sum_t E[z_dnk] w_dnt E[ln vocab_kt]
prob_words += np.sum(W[d, :].data[np.newaxis, :] * z * (diWordDists[:, wordIdx] - diWordDistSums[:, np.newaxis]))
# And finally the entropy of Z
ent_z -= np.dot(z * safe_log(z), W[d, :].data).sum()
# Next the link-topic assignments, note this is a PxK matrix
linkIdx, y = _infer_link_topics_at_d(d, L, topics, lse_at_k)
# Here we _start_ with the entropy of y
ent_y -= np.dot(L[d, :].data, y * safe_log(y)).sum()
# E[ln p(Y|topics) = sum_d sum_m sum_k E[y_dmk] E[ln topicDist_dk]
y *= L[d, :].data[:, np.newaxis]
prob_y += y.dot(topics[d, :].T).sum()
prob_y -= out_counts[d] * lse(topics[d, :])
# E[ln p(L|Y)] = sum_d sum_m sum_k sum_t E[y_dmk] l_dmp E[ln topics_pk]
prob_links += y.dot(topics[linkIdx, :].T).sum()
prob_links -= y.dot(lse_at_k).sum()
bound += (prob_z + ent_z + prob_words)
bound += (prob_y + ent_y + prob_links)
return bound
def train(data, model, query, plan, updateVocab=True):
'''
Infers the topic distributions in general, and specifically for
each individual datapoint,
Params:
data - the training data, we just use the DxT document-term matrix
model - the initial model configuration. This is MUTATED IN-PLACE
qyery - the query results - essentially all the "local" variables
matched to the given observations. Also MUTATED IN-PLACE
plan - how to execute the training process (e.g. iterations,
log-interval etc.)
Return:
The updated model object (note parameters are updated in place, so make a
defensive copy if you want it)
The query object with the update query parameters
'''
iterations, epsilon, logFrequency, fastButInaccurate, debug = \
plan.iterations, plan.epsilon, plan.logFrequency, plan.fastButInaccurate, plan.debug
docLens, topicMeans = \
query.docLens, query.topicDists
K, topicPrior, vocabPrior, wordDists, corpusTopicDist, dtype = \
model.K, model.topicPrior, model.vocabPrior, model.wordDists, model.corpusTopicDist, model.dtype
W = data.words
iters, bnds, likes = [], [], []
# Quick sanity check
if np.any(docLens < 1):
raise ValueError("Input document-term matrix contains at least one document with no words")
assert dtype == np.float64, "Only implemented for 64-bit floats"
for itr in range(iterations):
# E-Step
safe_log(wordDists, out=wordDists)
safe_log(corpusTopicDist, out=corpusTopicDist)
topicDists = W.dot(wordDists.T) + corpusTopicDist[np.newaxis, :]
#topicDists -= topicDists.max(axis=1)[:, np.newaxis] # TODO Ensure this is okay
norms = fns.logsumexp(topicDists, axis=1)
topicDists -= norms[:, np.newaxis]
np.exp(topicDists, out=topicDists)
# M-Step
wordDists = (W.T.dot(topicDists)).T
wordDists += vocabPrior
wordDists /= wordDists.sum(axis=1)[:, np.newaxis]
corpusTopicDist = topicDists.sum(axis=0)
corpusTopicDist[:] += topicPrior
corpusTopicDist /= corpusTopicDist.sum()
if itr % logFrequency == 0 or debug:
m = ModelState(K, topicPrior, vocabPrior, wordDists, corpusTopicDist, True, dtype, model.name)
q = QueryState(query.docLens, topicDists, True)
iters.append(itr)
bnds.append(var_bound(data, m, q))
likes.append(log_likelihood(data, m, q))
perp = perplexity_from_like(likes[-1], W.sum())
print("Iteration %d : Train Perp = %4.0f Bound = %.3f" % (itr, perp, bnds[-1]))
if len(iters) > 2 and iters[-1] > 50:
lastPerp = perplexity_from_like(likes[-2], W.sum())
if lastPerp - perp < 1:
break;
return ModelState(K, topicPrior, vocabPrior, wordDists, corpusTopicDist, True, dtype, model.name), \
QueryState(query.docLens, topicDists, True), \
(np.array(iters, dtype=np.int32), np.array(bnds), np.array(likes))
