def slice_signal(model, signal, sl):
assert signal.ndim == 1
if isinstance(sl, slice) and (sl.step is None or sl.step == 1):
return signal[sl]
else:
size = np.arange(signal.size)[sl].size
sliced_signal = Signal(np.zeros(size), name="%s.sliced" % signal.name)
model.add_op(SlicedCopy(signal, sliced_signal, a_slice=sl))
return sliced_signal
def build_connection(model, conn):
# Create random number generator
rng = np.random.RandomState(model.seeds[conn])
# Get input and output connections from pre and post
def get_prepost_signal(is_pre):
target = conn.pre_obj if is_pre else conn.post_obj
key = 'out' if is_pre else 'in'
if target not in model.sig:
raise ValueError("Building %s: the '%s' object %s "
"is not in the model, or has a size of zero." %
(conn, 'pre' if is_pre else 'post', target))
if key not in model.sig[target]:
raise ValueError("Error building %s: the '%s' object %s "
"has a '%s' size of zero." %
(conn, 'pre' if is_pre else 'post', target, key))
return model.sig[target][key]
model.sig[conn]['in'] = get_prepost_signal(is_pre=True)
model.sig[conn]['out'] = get_prepost_signal(is_pre=False)
weights = None
eval_points = None
solver_info = None
signal_size = conn.size_out
post_slice = conn.post_slice
# Figure out the signal going across this connection
in_signal = model.sig[conn]['in']
if (isinstance(conn.pre_obj, Node)
or (isinstance(conn.pre_obj, Ensemble)
and isinstance(conn.pre_obj.neuron_type, Direct))):
# Node or Decoded connection in directmode
sliced_in = slice_signal(model, in_signal, conn.pre_slice)
if conn.function is not None:
in_signal = Signal(np.zeros(conn.size_mid), name='%s.func' % conn)
model.add_op(
SimPyFunc(output=in_signal,
fn=conn.function,
t_in=False,
x=sliced_in))
else:
in_signal = sliced_in
elif isinstance(conn.pre_obj, Ensemble): # Normal decoded connection
eval_points, decoders, solver_info = build_decoders(model, conn, rng)
if conn.solver.weights:
model.sig[conn]['out'] = model.sig[conn.post_obj.neurons]['in']
signal_size = conn.post_obj.neurons.size_in
post_slice = Ellipsis # don't apply slice later
weights = decoders.T
else:
weights = multiply(conn.transform, decoders.T)
else:
in_signal = slice_signal(model, in_signal, conn.pre_slice)
# Add operator for applying weights
if weights is None:
weights = np.array(conn.transform)
if isinstance(conn.post_obj, Neurons):
gain = model.params[conn.post_obj.ensemble].gain[post_slice]
weights = multiply(gain, weights)
if conn.learning_rule is not None and weights.ndim < 2:
raise ValueError("Learning connection must have full transform matrix")
model.sig[conn]['weights'] = Signal(weights,
name="%s.weights" % conn,
readonly=True)
signal = Signal(np.zeros(signal_size), name="%s.weighted" % conn)
model.add_op(Reset(signal))
op = ElementwiseInc if weights.ndim < 2 else DotInc
model.add_op(
op(model.sig[conn]['weights'],
in_signal,
signal,
tag="%s.weights_elementwiseinc" % conn))
# Add operator for filtering
if conn.synapse is not None:
signal = model.build(conn.synapse, signal)
# Copy to the proper slice
model.add_op(
SlicedCopy(signal,
model.sig[conn]['out'],
b_slice=post_slice,
inc=True,
tag="%s.gain" % conn))
# Build learning rules
if conn.learning_rule is not None:
model.sig[conn]['weights'].readonly = False
model.add_op(PreserveValue(model.sig[conn]['weights']))
rule = conn.learning_rule
if is_iterable(rule):
for r in itervalues(rule) if isinstance(rule, dict) else rule:
model.build(r)
elif rule is not None:
model.build(rule)
model.params[conn] = BuiltConnection(eval_points=eval_points,
solver_info=solver_info,
weights=weights)
def build_connection(model, conn):
"""Builds a `.Connection` object into a model.
A brief summary of what happens in the connection build process,
in order:
1. Solve for decoders.
2. Combine transform matrix with decoders to get weights.
3. Add operators for computing the function
or multiplying neural activity by weights.
4. Call build function for the synapse.
5. Call build function for the learning rule.
6. Add operator for applying learning rule delta to weights.
Some of these steps may be altered or omitted depending on the parameters
of the connection, in particular the pre and post types.
Parameters
----------
model : Model
The model to build into.
conn : Connection
The connection to build.
Notes
-----
Sets ``model.params[conn]`` to a `.BuiltConnection` instance.
"""
# Create random number generator
rng = np.random.RandomState(model.seeds[conn])
# Get input and output connections from pre and post
def get_prepost_signal(is_pre):
target = conn.pre_obj if is_pre else conn.post_obj
key = 'out' if is_pre else 'in'
if target not in model.sig:
raise BuildError("Building %s: the %r object %s is not in the "
"model, or has a size of zero." %
(conn, 'pre' if is_pre else 'post', target))
if key not in model.sig[target]:
raise BuildError(
"Building %s: the %r object %s has a %r size of zero." %
(conn, 'pre' if is_pre else 'post', target, key))
return model.sig[target][key]
model.sig[conn]['in'] = get_prepost_signal(is_pre=True)
model.sig[conn]['out'] = get_prepost_signal(is_pre=False)
weights = None
eval_points = None
solver_info = None
signal_size = conn.size_out
post_slice = conn.post_slice
# Sample transform if given a distribution
transform = (conn.transform.sample(
conn.size_out, conn.size_mid, rng=rng) if isinstance(
conn.transform, Distribution) else np.array(conn.transform))
# Figure out the signal going across this connection
in_signal = model.sig[conn]['in']
if (isinstance(conn.pre_obj, Node)
or (isinstance(conn.pre_obj, Ensemble)
and isinstance(conn.pre_obj.neuron_type, Direct))):
# Node or Decoded connection in directmode
weights = transform
sliced_in = slice_signal(model, in_signal, conn.pre_slice)
if conn.function is not None:
in_signal = Signal(np.zeros(conn.size_mid), name='%s.func' % conn)
model.add_op(SimPyFunc(in_signal, conn.function, None, sliced_in))
else:
in_signal = sliced_in
elif isinstance(conn.pre_obj, Ensemble): # Normal decoded connection
eval_points, weights, solver_info = build_decoders(
model, conn, rng, transform)
if conn.solver.weights:
model.sig[conn]['out'] = model.sig[conn.post_obj.neurons]['in']
signal_size = conn.post_obj.neurons.size_in
post_slice = Ellipsis # don't apply slice later
else:
weights = transform
in_signal = slice_signal(model, in_signal, conn.pre_slice)
if isinstance(conn.post_obj, Neurons):
weights = multiply(
model.params[conn.post_obj.ensemble].gain[post_slice], weights)
# Add operator for applying weights
model.sig[conn]['weights'] = Signal(weights,
name="%s.weights" % conn,
readonly=True)
signal = Signal(np.zeros(signal_size), name="%s.weighted" % conn)
model.add_op(Reset(signal))
op = ElementwiseInc if weights.ndim < 2 else DotInc
model.add_op(
op(model.sig[conn]['weights'],
in_signal,
signal,
tag="%s.weights_elementwiseinc" % conn))
# Add operator for filtering
if conn.synapse is not None:
signal = model.build(conn.synapse, signal)
# Store the weighted-filtered output in case we want to probe it
model.sig[conn]['weighted'] = signal
# Copy to the proper slice
model.add_op(
SlicedCopy(signal,
model.sig[conn]['out'],
dst_slice=post_slice,
inc=True,
tag="%s.gain" % conn))
# Build learning rules
if conn.learning_rule is not None:
rule = conn.learning_rule
rule = [rule] if not is_iterable(rule) else rule
targets = []
for r in itervalues(rule) if isinstance(rule, dict) else rule:
model.build(r)
targets.append(r.modifies)
if 'encoders' in targets:
encoder_sig = model.sig[conn.post_obj]['encoders']
if not any(
isinstance(op, PreserveValue) and op.dst is encoder_sig
for op in model.operators):
encoder_sig.readonly = False
model.add_op(PreserveValue(encoder_sig))
if 'decoders' in targets or 'weights' in targets:
if weights.ndim < 2:
raise BuildError(
"'transform' must be a 2-dimensional array for learning")
model.sig[conn]['weights'].readonly = False
model.add_op(PreserveValue(model.sig[conn]['weights']))
model.params[conn] = BuiltConnection(eval_points=eval_points,
solver_info=solver_info,
transform=transform,
weights=weights)