def fflayer(tparams,
state_below,
options,
prefix='rconv',
activ='lambda x:tensor.tanh(x)',
**kwargs):
"""
@function:前馈网络层
"""
return eval(activ)(tensor.dot(state_below, tparams[pp(prefix, 'W')]) +
tparams[pp(prefix, 'b')])
def param_init_fflayer(options,
params,
prefix='ff',
nin=None,
nout=None,
ortho=True):
"""
@function:初始化前馈网络参数
"""
if nin is None:
nin = options['dim_proj']
if nout is None:
nout = options['dim_proj']
params[pp(prefix, 'W')] = norm_weight(nin, nout, scale=0.01, ortho=ortho)
params[pp(prefix, 'b')] = numpy.zeros((nout, )).astype('float32')
return params
def param_init_gru(options, params, prefix='gru', nin=None, dim=None):
"""
@function:初始化编码器GRU网络参数
"""
if nin is None:
nin = options['dim_proj']
if dim is None:
dim = options['dim_proj']
#embedding to gates transformation weights, biases (Wz,Wr,bz,br)
W = numpy.concatenate(
[norm_weight(nin, dim), norm_weight(nin, dim)], axis=1)
params[pp(prefix, 'W')] = W
params[pp(prefix, 'b')] = numpy.zeros((2 * dim, )).astype('float32')
#recurrent transformation weights for gates (Uz,Ur)
U = numpy.concatenate([ortho_weight(dim), ortho_weight(dim)], axis=1)
params[pp(prefix, 'U')] = U
#embedding to hidden state proposal weights, biases (Wt,Ut,bt)
Wx = norm_weight(nin, dim)
params[pp(prefix, 'Wx')] = Wx
params[pp(prefix, 'bx')] = numpy.zeros((dim, )).astype('float32')
#recurrent transformation weights for hidden state proposal
Ux = ortho_weight(dim)
params[pp(prefix, 'Ux')] = Ux
return params
def gru_layer(tparams,
state_below,
options,
prefix='gru',
mask=None,
emb_dropout=None,
rec_dropout=None,
profile=False,
**kwargs):
"""
@function:编码器GRU层的计算
"""
nsteps = state_below.shape[0]
if state_below.ndim == 3:
n_samples = state_below.shape[1]
else:
n_samples = 1
dim = tparams[pp(prefix, 'Ux')].shape[1]
if mask is None:
mask = tensor.alloc(1., state_below.shape[0], 1)
# utility function to slice a tensor
def _slice(_x, n, dim):
if _x.ndim == 3:
return _x[:, :, n * dim:(n + 1) * dim]
return _x[:, n * dim:(n + 1) * dim]
#state_below is the input word embeddings
# input to the gates, concatenated
state_below_ = tensor.dot(state_below*emb_dropout[0],tparams[pp(prefix,'W')]) + \
tparams[pp(prefix,'b')]
#input to compute the hidden state proposal
state_belowx = tensor.dot(state_below*emb_dropout[1],tparams[pp(prefix,'Wx')]) + \
tparams[pp(prefix,'bx')]
# step function to be used by scan
# arguments | sequences | outputs-info | non-seqs
def _step_slice(m_, x_, xx_, h_, U, Ux, rec_dropout):
preact = tensor.dot(h_ * rec_dropout[0], U)
preact += x_
#reset and upate gates
r = tensor.nnet.sigmoid(_slice(preact, 0, dim))
u = tensor.nnet.sigmoid(_slice(preact, 1, dim))
# compute the hidden state proposal
preactx = tensor.dot(h_ * rec_dropout[1], Ux)
preactx = preactx * r
preactx = preactx + xx_
#hidden state proposal
h = tensor.tanh(preactx)
#leaky itegrate and obtain next hidden state
h = u * h_ + (1. - u) * h
h = m_[:, None] * h + (1. - m_)[:, None] * h_
return h
# prepare scan arugments
seqs = [mask, state_below_, state_belowx]
init_states = [tensor.alloc(0., n_samples, dim)]
_step = _step_slice
shared_vars = [
tparams[pp(prefix, 'U')], tparams[pp(prefix, 'Ux')], rec_dropout
]
rval, updates = theano.scan(_step,
sequences=seqs,
outputs_info=init_states,
non_sequences=shared_vars,
name=pp(prefix, '_layers'),
n_steps=nsteps,
profile=profile,
strict=True)
rval = [rval]
return rval
def gru_cond_layer(tparams,
state_below,
options,
prefix='gru',
mask=None,
context=None,
one_step=False,
init_memory=None,
init_state=None,
context_mask=None,
emb_dropout=None,
rec_dropout=None,
ctx_dropout=None,
profile=False,
**kwargs):
"""
@function:解码器GRU层的计算
"""
assert context, 'Context must be provided'
if one_step:
assert init_state, 'previous state must be provided'
nsteps = state_below.shape[0]
if state_below.ndim == 3:
n_samples = state_below.shape[1]
else:
n_samples = 1
# mask
if mask is None:
mask = tensor.alloc(1., state_below.shape[0], 1)
dim = tparams[pp(prefix, 'Wcx')].shape[1]
# initial/previous state
if init_state is None:
init_state = tensor.alloc(0., n_samples, dim)
# projected context
assert context.ndim == 3, \
'Context must be 3-d: #annotation x #sample x dim'
pctx_ = tensor.dot(context*ctx_dropout[0], tparams[pp(prefix, 'Wc_att')]) +\
tparams[pp(prefix, 'b_att')]
def _slice(_x, n, dim):
if _x.ndim == 3:
return _x[:, :, n * dim:(n + 1) * dim]
return _x[:, n * dim:(n + 1) * dim]
# projected x
state_belowx = tensor.dot(state_below*emb_dropout[0], tparams[pp(prefix, 'Wx')]) +\
tparams[pp(prefix, 'bx')]
state_below_ = tensor.dot(state_below*emb_dropout[1], tparams[pp(prefix, 'W')]) +\
tparams[pp(prefix, 'b')]
def _step_slice(m_, x_, xx_, h_, ctx_, alpha_, pctx_, cc_, rec_dropout,
ctx_dropout, U, Wc, W_comb_att, U_att, c_tt, Ux, Wcx, U_n1,
Ux_n1, b_n1, bx_n1):
preact1 = tensor.dot(h_ * rec_dropout[0], U)
preact1 += x_
preact1 = tensor.nnet.sigmoid(preact1)
r1 = _slice(preact1, 0, dim)
u1 = _slice(preact1, 1, dim)
preactx1 = tensor.dot(h_ * rec_dropout[1], Ux)
preactx1 *= r1
preactx1 += xx_
h1 = tensor.tanh(preactx1)
h1 = u1 * h_ + (1. - u1) * h1
h1 = m_[:, None] * h1 + (1. - m_)[:, None] * h_
# attention
pstate_ = tensor.dot(h1 * rec_dropout[2], W_comb_att)
pctx__ = pctx_ + pstate_[None, :, :]
#pctx__ += xc_
pctx__ = tensor.tanh(pctx__)
alpha = tensor.dot(pctx__ * ctx_dropout[1], U_att) + c_tt
alpha = alpha.reshape([alpha.shape[0], alpha.shape[1]])
alpha = tensor.exp(alpha - alpha.max(0, keepdims=True)) #不同于 dl4mt
if context_mask:
alpha = alpha * context_mask
alpha = alpha / alpha.sum(0, keepdims=True)
ctx_ = (cc_ * alpha[:, :, None]).sum(0) # current context
preact2 = tensor.dot(h1 * rec_dropout[3], U_n1) + b_n1
preact2 += tensor.dot(ctx_ * ctx_dropout[2], Wc)
preact2 = tensor.nnet.sigmoid(preact2)
r2 = _slice(preact2, 0, dim)
u2 = _slice(preact2, 1, dim)
preactx2 = tensor.dot(h1 * rec_dropout[4], Ux_n1) + bx_n1
preactx2 *= r2
preactx2 += tensor.dot(ctx_ * ctx_dropout[3], Wcx)
h2 = tensor.tanh(preactx2)
h2 = u2 * h1 + (1. - u2) * h2
h2 = m_[:, None] * h2 + (1. - m_)[:, None] * h1
return h2, ctx_, alpha.T # pstate_, preact, preactx, r, u
seqs = [mask, state_below_, state_belowx]
#seqs = [mask, state_below_, state_belowx, state_belowc]
_step = _step_slice
shared_vars = [
tparams[pp(prefix, 'U')], tparams[pp(prefix, 'Wc')],
tparams[pp(prefix, 'W_comb_att')], tparams[pp(prefix, 'U_att')],
tparams[pp(prefix, 'c_tt')], tparams[pp(prefix, 'Ux')],
tparams[pp(prefix, 'Wcx')], tparams[pp(prefix, 'U_n1')],
tparams[pp(prefix,
'Ux_n1')], tparams[pp(prefix,
'b_n1')], tparams[pp(prefix, 'bx_n1')]
]
if one_step:
rval = _step(*(
seqs +
[init_state, None, None, pctx_, context, rec_dropout, ctx_dropout
] + shared_vars))
else:
rval, updates = theano.scan(
_step,
sequences=seqs,
outputs_info=[
init_state,
tensor.alloc(0., n_samples, context.shape[2]),
tensor.alloc(0., n_samples, context.shape[0])
],
non_sequences=[pctx_, context, rec_dropout, ctx_dropout] +
shared_vars,
name=pp(prefix, '_layers'),
n_steps=nsteps,
profile=profile,
strict=True)
return rval
def param_init_gru_cond(options,
params,
prefix='gru_cond',
nin=None,
dim=None,
dimctx=None,
nin_nonlin=None,
dim_nonlin=None):
"""
@function:初始化解码器GRU网络参数
"""
if nin is None:
nin = options['dim']
if dim is None:
dim = options['dim']
if dimctx is None:
dimctx = options['dim']
if nin_nonlin is None:
nin_nonlin = nin
if dim_nonlin is None:
dim_nonlin = dim
W = numpy.concatenate(
[norm_weight(nin, dim), norm_weight(nin, dim)], axis=1)
params[pp(prefix, 'W')] = W
params[pp(prefix, 'b')] = numpy.zeros((2 * dim, )).astype('float32')
U = numpy.concatenate([ortho_weight(dim_nonlin),
ortho_weight(dim_nonlin)],
axis=1)
params[pp(prefix, 'U')] = U
Wx = norm_weight(nin_nonlin, dim_nonlin)
params[pp(prefix, 'Wx')] = Wx
Ux = ortho_weight(dim_nonlin)
params[pp(prefix, 'Ux')] = Ux
params[pp(prefix, 'bx')] = numpy.zeros((dim_nonlin, )).astype('float32')
U_n1 = numpy.concatenate(
[ortho_weight(dim_nonlin),
ortho_weight(dim_nonlin)], axis=1)
params[pp(prefix, 'U_n1')] = U_n1
params[pp(prefix, 'b_n1')] = numpy.zeros(
(2 * dim_nonlin, )).astype('float32')
Ux_n1 = ortho_weight(dim_nonlin)
params[pp(prefix, 'Ux_n1')] = Ux_n1
params[pp(prefix, 'bx_n1')] = numpy.zeros((dim_nonlin, )).astype('float32')
#context to LSTM
Wc = norm_weight(dimctx, dim * 2)
params[pp(prefix, 'Wc')] = Wc
Wcx = norm_weight(dimctx, dim)
params[pp(prefix, 'Wcx')] = Wcx
#attention: context-> hidden
W_comb_att = norm_weight(dim, dimctx)
params[pp(prefix, 'W_comb_att')] = W_comb_att
#attention: context-> hidden
Wc_att = norm_weight(dimctx)
params[pp(prefix, 'Wc_att')] = Wc_att
#attention: hidden bias
b_att = numpy.zeros((dimctx, )).astype('float32')
params[pp(prefix, 'b_att')] = b_att
#attention:
U_att = norm_weight(dimctx, 1)
params[pp(prefix, 'U_att')] = U_att
c_att = numpy.zeros((1, )).astype('float32')
params[pp(prefix, 'c_tt')] = c_att
return params