'Sample the hidden units from the visible units.
This is the Positive phase of the Contrastive Divergence algorithm.
:param visible: activations of the visible units
:return: tuple(hidden probabilities, hidden binary states)'

def sample_hidden_from_visible(self, visible):

    hprobs = tf.nn.sigmoid(tf.add(tf.matmul(visible, self.W), self.bh_))
    hstates = utilities.sample_prob(hprobs, self.hrand)
    return (hprobs, hstates)
