def binary_decoder(decoder_params):
'a neural net with tanh layers until the final sigmoid layer'
nnet_params, (W_out, b_out) = unpack_binary_params(decoder_params)
nnet = compose(tanh_layer(W, b) for W, b in nnet_params)
Y = sigmoid_layer(W_out, b_out)
def decode(Z):
return Y(nnet(Z))
return decode
def binary_decoder(decoder_params):
'a neural net with tanh layers until the final sigmoid layer'
nnet_params, (W_out, b_out) = unpack_binary_params(decoder_params)
nnet = compose(tanh_layer(W, b) for W, b in nnet_params)
Y = sigmoid_layer(W_out, b_out)
def decode(Z):
return Y(nnet(Z))
return decode
def mlp_decode(z, phi, tanh_scale=10., sigmoid_output=True):
nnet_params, ((W_mu, b_mu), (W_sigma, b_sigma)) = phi[:-2], phi[-2:]
z = z if z.ndim == 3 else z[:,None,:] # ensure z.shape == (T, K, n)
nnet = compose(tanh_layer(W, b) for W, b in nnet_params)
mu = linear_layer(W_mu, b_mu)
log_sigmasq = linear_layer(W_sigma, b_sigma)
nnet_outputs = nnet(np.reshape(z, (-1, z.shape[-1])))
mu = sigmoid(mu(nnet_outputs)) if sigmoid_output else mu(nnet_outputs)
log_sigmasq = tanh_scale * np.tanh(log_sigmasq(nnet_outputs) / tanh_scale)
shape = z.shape[:-1] + (-1,)
return mu.reshape(shape), log_sigmasq.reshape(shape)
def encoder(encoder_params):
"a neural net with tanh layers until the final layer,"
"which generates mu and log_sigmasq separately"
nnet_params, (W_mu, b_mu), (W_sigma, b_sigma) = unpack_gaussian_params(encoder_params)
nnet = compose(tanh_layer(W, b) for W, b in nnet_params)
mu = linear_layer(W_mu, b_mu)
log_sigmasq = linear_layer(W_sigma, b_sigma)
def encode(X):
h = nnet(X)
return mu(h), log_sigmasq(h)
return encode
def mlp_recognize(x, psi, tanh_scale=10.):
nnet_params, ((W_h, b_h), (W_J, b_J)) = psi[:-2], psi[-2:]
T, p = x.shape[0], b_h.shape[0]
shape = x.shape[:-1] + (-1,)
nnet = compose(tanh_layer(W, b) for W, b in nnet_params)
h = linear_layer(W_h, b_h)
log_J = linear_layer(W_J, b_J)
nnet_outputs = nnet(np.reshape(x, (-1, x.shape[-1])))
J = -1./2 * np.exp(tanh_scale * np.tanh(log_J(nnet_outputs) / tanh_scale))
h = h(nnet_outputs)
logZ = np.zeros(shape[:-1])
return make_tuple(np.reshape(J, shape), np.reshape(h, shape), logZ)
def encoder(encoder_params):
'a neural net with tanh layers until the final layer,'
'which generates mu and log_sigmasq separately'
nnet_params, (W_mu, b_mu), (W_sigma, b_sigma) = \
unpack_gaussian_params(encoder_params)
nnet = compose(tanh_layer(W, b) for W, b in nnet_params)
mu = linear_layer(W_mu, b_mu)
log_sigmasq = linear_layer(W_sigma, b_sigma)
def encode(X):
h = nnet(X)
return mu(h), log_sigmasq(h)
return encode