def __init__(self, n_inputs=None, n_outputs=None, input_shape=None,
n_bypass=0,
density='mog',
n_hiddens=(10, 10), impute_missing=True, seed=None,
n_filters=(), filter_sizes=3, pool_sizes=2,
n_rnn=0,
**density_opts):
"""Initialize a mixture density network with custom layers
Parameters
----------
n_inputs : int
Total input dimensionality (data/summary stats)
n_outputs : int
Dimensionality of output (simulator parameters)
input_shape : tuple
Size to which data are reshaped before CNN or RNN
n_bypass : int
Number of elements at end of input which bypass CNN or RNN
density : string
Type of density condition on the network, can be 'mog' or 'maf'
n_components : int
Number of components of the mixture density
n_filters : list of ints
Number of filters per convolutional layer
n_hiddens : list of ints
Number of hidden units per fully connected layer
n_rnn : None or int
Number of RNN units
impute_missing : bool
If set to True, learns replacement value for NaNs, otherwise those
inputs are set to zero
seed : int or None
If provided, random number generator will be seeded
density_opts : dict
Options for the density estimator
"""
if n_rnn > 0 and len(n_filters) > 0:
raise NotImplementedError
assert isint(n_inputs) and isint(n_outputs)\
and n_inputs > 0 and n_outputs > 0
self.density = density.lower()
self.impute_missing = impute_missing
self.n_hiddens = list(n_hiddens)
self.n_outputs, self.n_inputs = n_outputs, n_inputs
self.n_bypass = n_bypass
self.n_rnn = n_rnn
self.n_filters, self.filter_sizes, self.pool_sizes, n_cnn = \
list(n_filters), filter_sizes, pool_sizes, len(n_filters)
if type(self.filter_sizes) is int:
self.filter_sizes = [self.filter_sizes for _ in range(n_cnn)]
else:
assert len(self.filter_sizes) >= n_cnn
if type(self.pool_sizes) is int:
self.pool_sizes = [self.pool_sizes for _ in range(n_cnn)]
else:
assert len(self.pool_sizes) >= n_cnn
self.iws = tt.vector('iws', dtype=dtype)
self.seed = seed
if seed is not None:
self.rng = np.random.RandomState(seed=seed)
else:
self.rng = np.random.RandomState()
lasagne.random.set_rng(self.rng)
self.input_shape = (n_inputs,) if input_shape is None else input_shape
assert np.prod(self.input_shape) + self.n_bypass == self.n_inputs
assert 1 <= len(self.input_shape) <= 3
# params: output placeholder (batch, self.n_outputs)
self.params = tensorN(2, name='params', dtype=dtype)
# stats : input placeholder, (batch, self.n_inputs)
self.stats = tensorN(2, name='stats', dtype=dtype)
# compose layers
self.layer = collections.OrderedDict()
# input layer, None indicates batch size not fixed at compile time
self.layer['input'] = ll.InputLayer(
(None, self.n_inputs), input_var=self.stats)
# learn replacement values
if self.impute_missing:
self.layer['missing'] = \
dl.ImputeMissingLayer(last(self.layer),
n_inputs=(self.n_inputs,))
else:
self.layer['missing'] = \
dl.ReplaceMissingLayer(last(self.layer),
n_inputs=(self.n_inputs,))
if self.n_bypass > 0 and (self.n_rnn > 0 or n_cnn > 0):
last_layer = last(self.layer)
bypass_slice = slice(self.n_inputs - self.n_bypass, self.n_inputs)
direct_slice = slice(0, self.n_inputs - self.n_bypass)
self.layer['bypass'] = ll.SliceLayer(last_layer, bypass_slice)
self.layer['direct'] = ll.SliceLayer(last_layer, direct_slice)
# reshape inputs prior to RNN or CNN step
if self.n_rnn > 0 or n_cnn > 0:
if len(n_filters) > 0 and len(self.input_shape) == 2: # 1 channel
rs = (-1, 1, *self.input_shape)
else:
if self.n_rnn > 0:
assert len(self.input_shape) == 2 # time, dim
else:
assert len(self.input_shape) == 3 # channel, row, col
rs = (-1, *self.input_shape)
# last layer is 'missing' or 'direct'
self.layer['reshape'] = ll.ReshapeLayer(last(self.layer), rs)
# recurrent neural net, input: (batch, sequence_length, num_inputs)
if self.n_rnn > 0:
self.layer['rnn'] = ll.GRULayer(last(self.layer), n_rnn,
only_return_final=True)
# convolutional net, input: (batch, channels, rows, columns)
if n_cnn > 0:
for l in range(n_cnn): # add layers
if self.pool_sizes[l] == 1:
padding = (self.filter_sizes[l] - 1) // 2
else:
padding = 0
self.layer['conv_' + str(l + 1)] = ll.Conv2DLayer(
name='c' + str(l + 1),
incoming=last(self.layer),
num_filters=self.n_filters[l],
filter_size=self.filter_sizes[l],
stride=(1, 1),
pad=padding,
untie_biases=False,
W=lasagne.init.GlorotUniform(),
b=lasagne.init.Constant(0.),
nonlinearity=lnl.rectify,
flip_filters=True,
convolution=tt.nnet.conv2d)
if self.pool_sizes[l] > 1:
self.layer['pool_' + str(l + 1)] = ll.MaxPool2DLayer(
name='p' + str(l + 1),
incoming=last(self.layer),
pool_size=self.pool_sizes[l],
stride=None,
ignore_border=True)
# flatten
self.layer['flatten'] = ll.FlattenLayer(
incoming=last(self.layer),
outdim=2)
# incorporate bypass inputs
if self.n_bypass > 0 and (self.n_rnn > 0 or n_cnn > 0):
self.layer['bypass_merge'] = lasagne.layers.ConcatLayer(
[self.layer['bypass'], last(self.layer)], axis=1)
if self.density == 'mog':
self.init_mdn(**density_opts)
elif self.density == 'maf':
self.init_maf(**density_opts)
else:
raise NotImplementedError
self.compile_funs() # theano functions
def __init__(self,
n_inputs,
n_outputs,
n_components=1,
n_filters=[],
n_hiddens=[10, 10],
n_rnn=None,
impute_missing=True,
seed=None,
svi=True):
"""Initialize a mixture density network with custom layers
Parameters
----------
n_inputs : int or tuple of ints or list of ints
Dimensionality of input
n_outputs : int
Dimensionality of output
n_components : int
Number of components of the mixture density
n_filters : list of ints
Number of filters per convolutional layer
n_hiddens : list of ints
Number of hidden units per fully connected layer
n_rnn : None or int
Number of RNN units
impute_missing : bool
If set to True, learns replacement value for NaNs, otherwise those
inputs are set to zero
seed : int or None
If provided, random number generator will be seeded
svi : bool
Whether to use SVI version or not
"""
self.impute_missing = impute_missing
self.n_components = n_components
self.n_filters = n_filters
self.n_hiddens = n_hiddens
self.n_outputs = n_outputs
self.svi = svi
self.iws = tt.vector('iws', dtype=dtype)
if n_rnn is None:
self.n_rnn = 0
else:
self.n_rnn = n_rnn
if self.n_rnn > 0 and len(self.n_filters) > 0:
raise NotImplementedError
self.seed = seed
if seed is not None:
self.rng = np.random.RandomState(seed=seed)
else:
self.rng = np.random.RandomState()
lasagne.random.set_rng(self.rng)
# cast n_inputs to tuple
if type(n_inputs) is int:
self.n_inputs = (n_inputs, )
elif type(n_inputs) is list:
self.n_inputs = tuple(n_inputs)
elif type(n_inputs) is tuple:
self.n_inputs = n_inputs
else:
raise ValueError('n_inputs type not supported')
# compose layers
self.layer = collections.OrderedDict()
# stats : input placeholder, (batch, *self.n_inputs)
if len(self.n_inputs) + 1 == 2:
self.stats = tt.matrix('stats', dtype=dtype)
elif len(self.n_inputs) + 1 == 3:
self.stats = tt.tensor3('stats', dtype=dtype)
elif len(self.n_inputs) + 1 == 4:
self.stats = tt.tensor4('stats', dtype=dtype)
else:
raise NotImplementedError
# input layer
self.layer['input'] = ll.InputLayer((None, *self.n_inputs),
input_var=self.stats)
# learn replacement values
if self.impute_missing:
self.layer['missing'] = dl.ImputeMissingLayer(
last(self.layer), n_inputs=self.n_inputs)
else:
self.layer['missing'] = dl.ReplaceMissingLayer(
last(self.layer), n_inputs=self.n_inputs)
# recurrent neural net
# expects shape (batch, sequence_length, num_inputs)
if self.n_rnn > 0:
if len(self.n_inputs) == 1:
rs = (-1, *self.n_inputs, 1)
self.layer['rnn_reshape'] = ll.ReshapeLayer(
last(self.layer), rs)
self.layer['rnn'] = ll.GRULayer(last(self.layer),
n_rnn,
only_return_final=True)
# convolutional layers
# expects shape (batch, num_input_channels, input_rows, input_columns)
if len(self.n_filters) > 0:
# reshape
if len(self.n_inputs) == 1:
raise NotImplementedError
elif len(self.n_inputs) == 2:
rs = (-1, 1, *self.n_inputs)
else:
rs = None
if rs is not None:
self.layer['conv_reshape'] = ll.ReshapeLayer(
last(self.layer), rs)
# add layers
for l in range(len(n_filters)):
self.layer['conv_' + str(l + 1)] = ll.Conv2DLayer(
name='c' + str(l + 1),
incoming=last(self.layer),
num_filters=n_filters[l],
filter_size=3,
stride=(2, 2),
pad=0,
untie_biases=False,
W=lasagne.init.GlorotUniform(),
b=lasagne.init.Constant(0.),
nonlinearity=lnl.rectify,
flip_filters=True,
convolution=tt.nnet.conv2d)
# flatten
self.layer['flatten'] = ll.FlattenLayer(incoming=last(self.layer),
outdim=2)
# hidden layers
for l in range(len(n_hiddens)):
self.layer['hidden_' + str(l + 1)] = dl.FullyConnectedLayer(
last(self.layer),
n_units=n_hiddens[l],
svi=svi,
name='h' + str(l + 1))
last_hidden = last(self.layer)
# mixture layers
self.layer['mixture_weights'] = dl.MixtureWeightsLayer(
last_hidden,
n_units=n_components,
actfun=lnl.softmax,
svi=svi,
name='weights')
self.layer['mixture_means'] = dl.MixtureMeansLayer(
last_hidden,
n_components=n_components,
n_dim=n_outputs,
svi=svi,
name='means')
self.layer['mixture_precisions'] = dl.MixturePrecisionsLayer(
last_hidden,
n_components=n_components,
n_dim=n_outputs,
svi=svi,
name='precisions')
last_mog = [
self.layer['mixture_weights'], self.layer['mixture_means'],
self.layer['mixture_precisions']
]
# output placeholder
self.params = tt.matrix('params',
dtype=dtype) # (batch, self.n_outputs)
# mixture parameters
# a : weights, matrix with shape (batch, n_components)
# ms : means, list of len n_components with (batch, n_dim, n_dim)
# Us : precision factors, n_components list with (batch, n_dim, n_dim)
# ldetUs : log determinants of precisions, n_comp list with (batch, )
self.a, self.ms, precision_out = ll.get_output(last_mog,
deterministic=False)
self.Us = precision_out['Us']
self.ldetUs = precision_out['ldetUs']
self.comps = {
**{
'a': self.a
},
**{'m' + str(i): self.ms[i]
for i in range(self.n_components)},
**{'U' + str(i): self.Us[i]
for i in range(self.n_components)}
}
# log probability of y given the mixture distribution
# lprobs_comps : log probs per component, list of len n_components with (batch, )
# probs : log probs of mixture, (batch, )
self.lprobs_comps = [
-0.5 * tt.sum(tt.sum(
(self.params - m).dimshuffle([0, 'x', 1]) * U, axis=2)**2,
axis=1) + ldetU
for m, U, ldetU in zip(self.ms, self.Us, self.ldetUs)
]
self.lprobs = (MyLogSumExp(tt.stack(self.lprobs_comps, axis=1) + tt.log(self.a), axis=1) \
- (0.5 * self.n_outputs * np.log(2 * np.pi))).squeeze()
# the quantities from above again, but with deterministic=True
# --- in the svi case, this will disable injection of randomness;
# the mean of weights is used instead
self.da, self.dms, dprecision_out = ll.get_output(last_mog,
deterministic=True)
self.dUs = dprecision_out['Us']
self.dldetUs = dprecision_out['ldetUs']
self.dcomps = {
**{
'a': self.da
},
**{'m' + str(i): self.dms[i]
for i in range(self.n_components)},
**{'U' + str(i): self.dUs[i]
for i in range(self.n_components)}
}
self.dlprobs_comps = [
-0.5 * tt.sum(tt.sum(
(self.params - m).dimshuffle([0, 'x', 1]) * U, axis=2)**2,
axis=1) + ldetU
for m, U, ldetU in zip(self.dms, self.dUs, self.dldetUs)
]
self.dlprobs = (MyLogSumExp(tt.stack(self.dlprobs_comps, axis=1) + tt.log(self.da), axis=1) \
- (0.5 * self.n_outputs * np.log(2 * np.pi))).squeeze()
# parameters of network
self.aps = ll.get_all_params(last_mog) # all parameters
self.mps = ll.get_all_params(last_mog, mp=True) # means
self.sps = ll.get_all_params(last_mog, sp=True) # log stds
# weight and bias parameter sets as seperate lists
self.mps_wp = ll.get_all_params(last_mog, mp=True, wp=True)
self.sps_wp = ll.get_all_params(last_mog, sp=True, wp=True)
self.mps_bp = ll.get_all_params(last_mog, mp=True, bp=True)
self.sps_bp = ll.get_all_params(last_mog, sp=True, bp=True)
# theano functions
self.compile_funs()
self.iws = tt.vector('iws', dtype=dtype)