Bernoulli Mixture Models on MNIST

1

Hi guys. I’m trying to recreate the Bernoulli Mixture Model over binarized MNIST digits from Section 9.3.3 of Bishop’s textbook in Edward, but am struggling with the ParamMixture() class.

So far, I have:

N = 10000
K = 10
D = 28*28

pi = Dirichlet(tf.ones(K), sample_shape=D)
mu = Beta(tf.ones(D),tf.ones(D),sample_shape=K)
x = ParamMixture(pi, {'probs': mu}, Bernoulli, sample_shape=N)
z = x.cat

This allows me to define a ParamMixture with the right number of dimensions. However, I get an error during training: Incompatible shapes: [10000,10,784] vs. [10000,784,10]

If I try to change any of the shapes in the model parameters, the ParamMixture complains; if I have a working ParamMixture, I get the error during inference.

In short: does anyone have an example of how to create a multi-dimensional Bernoulli Mixture Model? Any help would be greatly appreciated!

2

Can you report your Edward and TensorFlow version? I ran the code on 1.3.3 and the latest development version. Both ran successfully.

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3

Thanks for responding! To clarify, the code posted above runs fine, but I get the Incompatible shapes error when I run:

T = 500 # EDIT: declared T
qpi = Empirical(tf.Variable(tf.ones([T, D, K]) / K))
qmu = Empirical(tf.Variable(tf.zeros([T, K, D])))
qz = Empirical(tf.Variable(tf.zeros([T, N, D], dtype=tf.int32)))

Inference = ed.Gibbs({pi: qpi, mu: qmu, z: qz}, data={x: x_data})
inference.initialize()

sess = ed.get_session()
tf.global_variables_initializer().run()

for _ in range(inference.n_iter):
  info_dict = inference.update()
  inference.print_progress(info_dict)

I am running edward 1.3.3 and tensorflow 1.2.0-rc0 in virtualenv 15.1.0 under python 2.7.10, on macOS 10.12.1.

6

I just discovered the on-going discussion here, which discusses the same question:
https://github.com/blei-lab/edward/issues/686

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