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Simplify LDA input parameterization #143
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Original file line number | Diff line number | Diff line change |
---|---|---|
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@@ -2,28 +2,26 @@ data { | |
int<lower=2> K; // num topics | ||
int<lower=2> V; // num words | ||
int<lower=1> M; // num docs | ||
int<lower=1> N; // total word instances | ||
int<lower=1,upper=V> w[N]; // word n | ||
int<lower=1,upper=M> doc[N]; // doc ID for word n | ||
int<lower=0> corpus[M,V]; // word freq matrix, doc x word | ||
vector<lower=0>[V] beta; // word prior | ||
} | ||
parameters { | ||
vector[K] mu; // topic mean | ||
corr_matrix[K] Omega; // correlation matrix | ||
vector<lower=0>[K] sigma; // scales | ||
vector[K] eta[M]; // logit topic dist for doc m | ||
vector[K] eta[M]; // logit topic dist for doc m | ||
simplex[V] phi[K]; // word dist for topic k | ||
} | ||
transformed parameters { | ||
simplex[K] theta[M]; // simplex topic dist for doc m | ||
cov_matrix[K] Sigma; // covariance matrix | ||
for (m in 1:M) | ||
theta[m] <- softmax(eta[m]); | ||
theta[m] = softmax(eta[m]); | ||
for (m in 1:K) { | ||
Sigma[m,m] <- sigma[m] * sigma[m] * Omega[m,m]; | ||
Sigma[m,m] = sigma[m] * sigma[m] * Omega[m,m]; | ||
for (n in (m+1):K) { | ||
Sigma[m,n] <- sigma[m] * sigma[n] * Omega[m,n]; | ||
Sigma[n,m] <- Sigma[m,n]; | ||
Sigma[m,n] = sigma[m] * sigma[n] * Omega[m,n]; | ||
Sigma[n,m] = Sigma[m,n]; | ||
} | ||
} | ||
} | ||
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@@ -38,10 +36,16 @@ model { | |
for (m in 1:M) | ||
eta[m] ~ multi_normal(mu,Sigma); | ||
// token probabilities | ||
for (n in 1:N) { | ||
real gamma[K]; | ||
for (k in 1:K) | ||
gamma[k] <- log(theta[doc[n],k]) + log(phi[k,w[n]]); | ||
increment_log_prob(log_sum_exp(gamma)); // likelihood | ||
for (i in 1:M) { | ||
for (j in 1:V) { | ||
int count = corpus[i,j]; | ||
real gamma[K]; | ||
if (count > 0) { | ||
for (k in 1:K) { | ||
gamma[k] = (log(theta[i,k]) + log(phi[k,j]))*count; | ||
} | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Rather than looping to define
The loop works for the
|
||
increment_log_prob(log_sum_exp(gamma)); // likelihood | ||
} | ||
} | ||
} | ||
} |
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Thanks for replacing
<-
--- that would be a good change for the original model, as well as replacingincrement_log_prob
withtarget +=
.square(sigma[m])
will be a bit more efficient, as would besigma[m]^2
.