def computeLogZ(self):
"""
Provides Zs, logZ
"""
if 'logZ' in self.__dict__:
return
self.computeLogV1()
L = self.traj.L
self.logZs = [dot(self.traj.features_np[0], self.theta)]
assert not np.isnan(self.logZs[0]).any(), \
(self.traj.features_np[0], self.theta)
for l in range(1, L):
N_l = self.traj.num_choices[l]
l_vec = MINUS_INF * np.ones((N_l))
conns_back = self.traj.connections_backward[l]
w = dot(self.traj.features_np[l], self.theta)
assert not np.isnan(w).any()
for i in range(N_l):
if i in conns_back:
l_vec[i] = w[i] + lse([self.logZs[l-1][j] for j in conns_back[i]])
assert not np.isnan(l_vec[i]).any()
assert not np.isnan(l_vec).any()
self.logZs.append(l_vec)
assert(len(self.logZs) == L)
self.logZ = lse(self.logZs[L-1])
assert not np.isnan(self.logZ).any()
# Make sure we do not overflow.
if self.logZ < 100 and self.logZ > -100:
self.Z = exp(self.logZ)
def computeValue(self):
"""
Calls LogZ.
Provides logValue
"""
if 'logValue' in self.__dict__:
return
self.computeSStats()
self.computeLogV1()
self.computeLogZ()
L = self.traj.L
self.logValues = [dot(self.traj.features_np[0],
self.theta) - dot(self.sstats[0], self.theta)]
assert not np.isnan(self.logValues[0]).any(), \
(self.traj.features_np[0], self.theta)
assert lse(self.logValues[0]) >= 0
for l in range(1, L):
N_l = self.traj.num_choices[l]
l_vec = MINUS_INF * np.ones((N_l))
conns_back = self.traj.connections_backward[l]
w = dot(self.traj.features_np[l],
self.theta) - dot(self.sstats[l], self.theta)
assert not np.isnan(w).any()
for i in range(N_l):
if i in conns_back:
l_vec[i] = w[i] + lse([self.logValues[l-1][j] \
for j in conns_back[i]])
assert not np.isnan(l_vec[i]).any()
self.logValues.append(l_vec)
# assert(lse(l_vec) >= -1e-2)
assert not np.isnan(l_vec).any()
assert(len(self.logValues) == L)
self.logValue = -lse(self.logValues[L-1])
assert not np.isnan(self.logZ).any()
def computeLogZ(self):
""" Reference computation of Z and logZ, in the log domain.
Very inefficient.
Provides:
- logZ
Debug info:
- Z
"""
if 'logZ' in self.__dict__:
return
L = self.traj.L
# Weighting statistics.
self.Z = 0
self.logZ = MINUS_INF
# List of the log weights of all the possible trajectories.
intermediate_log_vals = []
def inner(indices):
""" Inner working function. """
L_ = len(indices)
if L_ == L:
v1 = np.zeros_like(self.theta)
for l in range(L):
v1 += self.traj.features_np[l][indices[l]]
intermediate_log_vals.append(dot(v1, self.theta))
else:
i = indices[-1]
for j in self.traj.connections_forward[L_-1][i]:
inner(indices + [j])
for i in range(self.traj.num_choices[0]):
inner([i])
self.logZ = lse(intermediate_log_vals)
# Make sure we do not overflow.
if self.logZ < 100 and self.logZ > -100:
self.Z = exp(self.logZ)
def computeProbs(self):
""" Compute probabilities.
"""
if 'probabilities' in self.__dict__:
return
inf = float('inf')
# Compute the weights
self.log_ws = []
for l in range(self.traj.L):
self.log_ws.append(dot(self.traj.features_np[l], self.theta))
# Forward pass
# Init:
self.log_forward = [np.zeros(N_l) for N_l in self.traj.num_choices]
self.log_forward[0] = self.log_ws[0] - lse(self.log_ws[0])
for l in range(1, self.traj.L):
N_l = self.traj.num_choices[l]
qs = -inf * np.ones(N_l)
for i in range(N_l):
if i in self.traj.connections_backward[l]:
log_s = lse([self.log_forward[l-1][j] \
for j in self.traj.connections_backward[l][i]])
qs[i] = self.log_ws[l][i] + log_s
self.log_forward[l] = qs - lse(qs)
# Backward pass
self.log_backward = [np.zeros(N_l, dtype=np.float64) \
for N_l in self.traj.num_choices]
# Backward pass
# A bit more complicated because we need to do it again for every chunk.
for l in range(self.traj.L):
self.log_backward[l] = self.computeLogBackward(l, min(l+self.k, \
self.traj.L-1))
# Product:
self.probabilities = []
self.log_probabilities = []
for l in range(self.traj.L):
log_ps = self.log_forward[l] + self.log_backward[l]
log_ps -= max(log_ps)
# Aggressively clamp the values that are too low to prevent an underflow
log_ps[log_ps < -200] = -200
self.log_probabilities.append(log_ps - lse(log_ps))
ps = exp(log_ps)
assert sum(ps) > 0, (l, log_ps, self.log_forward[l],
self.log_backward[l])
ps /= sum(ps)
self.probabilities.append(ps)
def computeProbs(self):
""" Compute probabilities.
"""
if 'probabilities' in self.__dict__:
return
inf = float('inf')
# Compute the weights
self.log_ws = []
for l in range(self.traj.L):
self.log_ws.append(dot(self.traj.features_np[l], self.theta))
# Forward pass
# Init:
self.log_forward = [np.zeros(N_l) for N_l in self.traj.num_choices]
self.log_forward[0] = self.log_ws[0] - lse(self.log_ws[0])
for l in range(1, self.traj.L):
N_l = self.traj.num_choices[l]
qs = -inf * np.ones(N_l)
for i in range(N_l):
if i in self.traj.connections_backward[l]:
log_s = lse([self.log_forward[l-1][j] \
for j in self.traj.connections_backward[l][i]])
qs[i] = self.log_ws[l][i] + log_s
self.log_forward[l] = qs - lse(qs)
# Backward pass
self.log_backward = [np.zeros(N_l, dtype=np.float64) \
for N_l in self.traj.num_choices]
# Backward pass
# A bit more complicated because we need to do it again for every chunk.
for l in range(self.traj.L):
self.log_backward[l] = self.computeLogBackward(l, min(l+self.k, \
self.traj.L-1))
# Product:
self.probabilities = []
self.log_probabilities = []
for l in range(self.traj.L):
log_ps = self.log_forward[l] + self.log_backward[l]
log_ps -= max(log_ps)
# Aggressively clamp the values that are too low to prevent an underflow
log_ps[log_ps < -200] = -200
self.log_probabilities.append(log_ps - lse(log_ps))
ps = exp(log_ps)
assert sum(ps) > 0, (l, log_ps, self.log_forward[l], self.log_backward[l])
ps /= sum(ps)
self.probabilities.append(ps)
def computeLogBackward(self, t, t_start):
""" Computes backward recursion for index t, \
starting at index t_start >= t.
Does not modify the function. Returns the vector of backward values.
"""
assert t_start >= t
assert self.traj.L > t_start
inf = float('inf')
# Intermediate vectors
vs = []
# Initizaliation
N_t_start = self.traj.num_choices[t_start]
vs.append(np.zeros(N_t_start, dtype=np.float64))
for l in range(t, t_start)[::-1]:
N_l = self.traj.num_choices[l]
qs = -inf * np.ones(N_l)
for i in range(N_l):
if i in self.traj.connections_forward[l]:
log_s = lse([vs[-1][j] \
for j in self.traj.connections_forward[l][i]])
qs[i] = self.log_ws[l][i] + log_s
vs.append(qs - lse(qs))
return vs[-1]
def computeLogBackward(self, t, t_start):
""" Computes backward recursion for index t, \
starting at index t_start >= t.
Does not modify the function. Returns the vector of backward values.
"""
assert t_start >= t
assert self.traj.L > t_start
inf = float('inf')
# Intermediate vectors
vs = []
# Initizaliation
N_t_start = self.traj.num_choices[t_start]
vs.append(np.zeros(N_t_start, dtype=np.float64))
for l in range(t, t_start)[::-1]:
N_l = self.traj.num_choices[l]
qs = -inf * np.ones(N_l)
for i in range(N_l):
if i in self.traj.connections_forward[l]:
log_s = lse([vs[-1][j] \
for j in self.traj.connections_forward[l][i]])
qs[i] = self.log_ws[l][i] + log_s
vs.append(qs - lse(qs))
return vs[-1]
def test_1():
""" test_1 """
v = [1, 2, 0.0]
lv = [log_safe(x) for x in v]
assert abs(log(3) - lse(lv)) < 1e-6, (v, lv)
def test_1(): """ test_1 """ v = [1, 2, 0.0] lv = [log_safe(x) for x in v] assert abs(log(3) - lse(lv)) < 1e-6, (v, lv)
