def expectation(model, instance):
'''
Perform forward-backward algorithm to calculate the second component
of the detrieve.
'''
# get the cached score
L = len(instance)
T = model.nr_tags
A = model.nr_attrs
g0, g = build_score_cache(model.w, L, T, A, instance)
a = forward(g0, g, L, T)
b = backward(g, L, T)
logZ = logsumexp(a[L-1,:])
E = defaultdict(float)
f = instance.features_table
c = exp(g0 + b[0,:] - logZ).clip(0., 1.)
for j in xrange(T):
for k in f[0,None,j]:
E[k] += c[j]
for i in xrange(1, L):
c = exp(add.outer(a[i-1,:], b[i,:]) + g[i,:,:] - logZ).clip(0.,1.)
for j in range(T):
for k in range(T):
for e in f[i,j,k]:
E[e] += c[j,k]
return E
def expectation(model, instance):
'''
Perform forward-backward algorithm to calculate the second component
of the detrieve.
'''
# get the cached score
L = len(instance)
T = model.nr_tags
A = model.nr_attrs
g0, g = build_score_cache(model.w, L, T, A, instance)
a = forward(g0, g, L, T)
b = backward(g, L, T)
logZ = logsumexp(a[L - 1, :])
E = defaultdict(float)
f = instance.features_table
c = exp(g0 + b[0, :] - logZ).clip(0., 1.)
for j in xrange(T):
for k in f[0, None, j]:
E[k] += c[j]
for i in xrange(1, L):
c = exp(add.outer(a[i - 1, :], b[i, :]) + g[i, :, :] - logZ).clip(
0., 1.)
for j in range(T):
for k in range(T):
for e in f[i, j, k]:
E[e] += c[j, k]
return E
def viterbi(model, instance):
'''
'''
L = len(instance)
T = model.nr_tags
A = model.nr_attrs
build_instance(model.attrs, model.tags, instance, False)
g0, g = build_score_cache(model.w, L, T, A, instance)
destroy_instance(instance)
s, p = argmax(g0, g, L, T)
v, i = s[L - 1].argmax(), L - 1
ret = []
while i >= 0:
ret.append(v)
v = p[i][v]
i -= 1
ret.reverse()
return ret
def viterbi(model, instance):
'''
'''
L = len(instance)
T = model.nr_tags
A = model.nr_attrs
build_instance(model.attrs, model.tags, instance, False)
g0, g = build_score_cache(model.w, L, T, A, instance)
destroy_instance(instance)
s, p = argmax(g0, g, L, T)
v, i = s[L -1].argmax(), L -1
ret = []
while i >= 0:
ret.append(v)
v = p[i][v]
i -= 1
ret.reverse()
return ret
