Python tensor.switch函数代码示例

def mindist(translate, min_so_far, ro, rd):
    # ro: 3
    # transalate: nbatch * 3
    # min_so_far: nbatch * width * height
    # rd: width * height * 3
    ro = ro + translate
    # d_o = T.dot(rd, ro)   # 640, 480
    # d_o = dotty(rd, ro, axis=1)
    d_o = T.tensordot(rd, ro, axes=[2,1])
    o_o =  T.sum(ro**2,axis=1)
    b = 2*d_o
    c = o_o - 0.001 #FIXME, remove this squaring
    inner = b **2 - 4 * c   # 640 480
    does_not_intersect = inner < 0.0
    minus_b = -b
    # sqrt_inner = T.sqrt(T.maximum(0.0001, inner))
    eps = 1e-9
    background_dist = 10.0
    sqrt_inner = T.sqrt(T.maximum(eps, inner))
    root1 = (minus_b - sqrt_inner)/2.0
    root2 = (minus_b + sqrt_inner)/2.0
    depth = T.switch(does_not_intersect, background_dist,
                        T.switch(root1 > 0, root1,
                        T.switch(root2 > 0, root2, background_dist)))
    return T.min([min_so_far, depth], axis=0)

 def s_logprior(self, s_params, strength=10.0):
     # -- I don't know what distribution this would be
     #    but I think it makes a nice shape
     s_alpha, s_cond_x, s_cond_y = self.unpack(s_params)
     n_alpha_min = self._alpha_from_l(self._lenscales_min)
     n_alpha_max = self._alpha_from_l(self._lenscales_max)
     #return strength * (alpha - alpha_min) ** 2
     log0 = -10000
     width = n_alpha_max - n_alpha_min
     #alpha_mean = 0.5 * (alpha_max + alpha_min)
     energy = strength * 0.5 * (s_alpha - n_alpha_max) ** 2 / width ** 2
     lenscale_logprior = TT.switch(s_alpha < n_alpha_min,
                                   log0,
                                   TT.switch(s_alpha < n_alpha_max,
                                             -energy,
                                             log0)).sum()
     if self._conditional:
         diff_x = s_cond_x
         diff_y = s_cond_y - 1
         rval = (lenscale_logprior
                 + TT.dot(diff_x, diff_x)
                 + TT.dot(diff_y, diff_y))
     else:
         rval = lenscale_logprior
     assert rval.ndim == 0
     return rval

 def backward_V_step(rewards,is_alive,next_Vpred,time_i, 
                     next_Vref,
                     *args):
     
     
     
     propagated_Vref = T.switch(is_alive,
                        rewards + gamma_or_gammas * next_Vref, #assumes optimal next action
                        0.
                       )
     
     if n_steps is None:
         this_Vref = propagated_Vref
     else:
         
         Vref_at_tmax = T.switch(is_alive,
                        rewards + gamma_or_gammas *next_Vpred,
                        0.
                       )
         
         this_Vref = T.switch(T.eq(time_i % n_steps,0), #if Tmax
                                     Vref_at_tmax,  #use special case values
                                     propagated_Vref #else use generic ones
                                )
                                      
                              
     
     
     
     return this_Vref

def T_subspacel1_slow_shrinkage_conv(a, L, lam_sparse, lam_slow, imshp,kshp,featshp,stride=(1,1),small_value=.001):
    featshp = (imshp[0],kshp[0],featshp[2],featshp[3]) # num images, features, szy, szx
    features = T.reshape(T.transpose(a),featshp,ndim=4)

    amp = T.sqrt(features[:,::2,:,:]**2 + features[:,1::2,:,:]**2 + small_value)
    #damp = amp[:,1:] - amp[:,:-1]

    # compose slow shrinkage with subspace l1 shrinkage

    # slow shrinkage
    div = T.zeros_like(amp)
    d1 = amp[1:,:,:,:] - amp[:-1,:,:,:]
    d2 = d1[1:,:,:,:] - d1[:-1,:,:,:]
    div = T.set_subtensor(div[1:-1,:,:,:], -d2)
    div = T.set_subtensor(div[0,:,:,:], -d1[0,:,:,:])
    div = T.set_subtensor(div[-1,:,:,:], d1[-1,:,:,:])
    slow_amp_shrinkage = 1 - (lam_slow / L) * (div / amp)
    slow_amp_value = T.switch(T.gt(slow_amp_shrinkage, 0), slow_amp_shrinkage, 0)
    slow_shrinkage_prox_a = slow_amp_value * features[:, ::2, :,:]
    slow_shrinkage_prox_b = slow_amp_value * features[:,1::2, :,:]

    # subspace l1 shrinkage
    amp_slow_shrinkage_prox = T.sqrt(slow_shrinkage_prox_a ** 2 + slow_shrinkage_prox_b ** 2)
    #amp_shrinkage = 1. - (lam_slow*lam_sparse/L)*amp_slow_shrinkage_prox
    amp_shrinkage = 1. - (lam_sparse / L) / amp_slow_shrinkage_prox
    amp_value = T.switch(T.gt(amp_shrinkage, 0.), amp_shrinkage, 0.)
    subspacel1_prox = T.zeros_like(features)
    subspacel1_prox = T.set_subtensor(subspacel1_prox[:, ::2, :,:], amp_value * slow_shrinkage_prox_a)
    subspacel1_prox = T.set_subtensor(subspacel1_prox[:,1::2, :,:], amp_value * slow_shrinkage_prox_b)

    reshape_subspacel1_prox = T.transpose(T.reshape(subspacel1_prox,(featshp[0],featshp[1]*featshp[2]*featshp[3]),ndim=2))
    return reshape_subspacel1_prox

	def create_cost_fun (self):

		# create a cost function that
		# takes each prediction at every timestep
		# and guesses next timestep's value:
		what_to_predict = self.input_mat[:, 1:]
		# because some sentences are shorter, we
		# place masks where the sentences end:
		# (for how long is zero indexed, e.g. an example going from `[2,3)`)
		# has this value set 0 (here we substract by 1):
		for_how_long = self.for_how_long - 1
		# all sentences start at T=0:
		starting_when = T.zeros_like(self.for_how_long)
								 
		self.lstm_cost = masked_loss(self.lstm_predictions,
								what_to_predict,
								for_how_long,
								starting_when).sum()

		zero_entropy = T.zeros_like(self.entropy)
		real_entropy = T.switch(self.mask_matrix,self.entropy,zero_entropy)
		zero_key_entropy = T.zeros_like(self.key_entropy)
		real_key_entropy = T.switch(self.mask_matrix,self.key_entropy,zero_key_entropy)

		self.final_cost = masked_loss(self.final_predictions,
								what_to_predict,
								for_how_long,
								starting_when).sum()+self.entropy_reg*real_entropy.sum()+self.key_entropy_reg*real_key_entropy.sum()

    def out_shape(imgshape, ds, ignore_border=False):
        """Return the shape of the output from this op, for input of given shape and flags.

        :param imgshape: the shape of a tensor of images. The last two elements are interpreted
        as the number of rows, and the number of cols.
        :type imgshape: tuple, list, or similar of integer or
        scalar Theano variable.

        :param ds: downsample factor over rows and columns
        :type ds: list or tuple of two ints

        :param ignore_border: if ds doesn't divide imgshape, do we include an extra row/col of
        partial downsampling (False) or ignore it (True).
        :type ignore_border: bool

        :rtype: list
        :returns: the shape of the output from this op, for input of given shape.  This will
        have the same length as imgshape, but with last two elements reduced as per the
        downsampling & ignore_border flags.
        """
        if len(imgshape) < 2:
            raise TypeError("imgshape must have at least two elements (rows, cols)")
        r, c = imgshape[-2:]
        rval = list(imgshape[:-2]) + [r // ds[0], c // ds[1]]

        if not ignore_border:
            if isinstance(r, theano.Variable):
                rval[-2] = tensor.switch(r % ds[0], rval[-2] + 1, rval[-2])
            elif r % ds[0]:
                rval[-2] += 1
            if isinstance(c, theano.Variable):
                rval[-1] = tensor.switch(c % ds[1], rval[-1] + 1, rval[-1])
            elif c % ds[1]:
                rval[-1] += 1
        return rval

    def mcmc(ll, *frvs):
        full_observations = dict(observations)
        full_observations.update(dict([(rv, s) for rv, s in zip(free_RVs, frvs)]))
        
        loglik = -full_log_likelihood(full_observations)

        proposals = free_RVs_prop
        H = tensor.add(*[tensor.sum(tensor.sqr(p)) for p in proposals])/2. + loglik

# -- this should be an inner loop
        g = []
        g.append(tensor.grad(loglik, frvs))
        
        proposals = [(p - epsilon*gg[0]/2.) for p, gg in zip(proposals, g)]

        rvsp = [(rvs + epsilon*rvp) for rvs,rvp in zip(frvs, proposals)]
        
        full_observations = dict(observations)
        full_observations.update(dict([(rv, s) for rv, s in zip(free_RVs, rvsp)]))
        new_loglik = -full_log_likelihood(full_observations)
        
        gnew = []
        gnew.append(tensor.grad(new_loglik, rvsp))
        proposals = [(p - epsilon*gn[0]/2.) for p, gn in zip(proposals, gnew)]
# --
        
        Hnew = tensor.add(*[tensor.sum(tensor.sqr(p)) for p in proposals])/2. + new_loglik

        dH = Hnew - H
        accept = tensor.or_(dH < 0., U < tensor.exp(-dH))

        return [tensor.switch(accept, -new_loglik, ll)] + \
            [tensor.switch(accept, p, f) for p, f in zip(rvsp, frvs)], \
            {}, theano.scan_module.until(accept)

    def _activation(self, Y, L, M, W):
        """Returns the activation for a given input.

        Derived from the generative model formulation of hierarchical
        Poisson mixtures, the formular for the activation in the network
        reads as follows:
        I_c =
         \sum_d \log(W_{cd})y_d + \log(M_{lc})        for labeled data
         \sum_d \log(W_{cd})y_d + \log(\sum_k M_{kc}) for unlabeled data
        s_c = softmax(I_c)
        """
        # first: complete inference to find label
        # Input integration:
        I = T.tensordot(Y,T.log(W),axes=[1,1])
        # recurrent term:
        vM = M[L]
        L_index = T.eq(L,-1).nonzero()
        vM = T.set_subtensor(vM[L_index], T.sum(M, axis=0))
        # numeric trick to prevent overflow in the exp-function
        max_exponent = 86. - T.ceil(T.log(I.shape[1].astype('float32')))
        scale = T.switch(
            T.gt(T.max(I, axis=1, keepdims=True), max_exponent),
            T.max(I, axis=1, keepdims=True) - max_exponent,
            0.)
        # numeric approximation to prevent underflow in the exp-function:
        # map too low values of I to a fixed minimum value
        min_exponent = -87. + T.ceil(T.log(I.shape[1].astype('float32')))
        I = T.switch(
            T.lt(I-scale, min_exponent),
            scale+min_exponent,
            I)
        # activation: recurrent softmax with overflow protection
        s = vM*T.exp(I-scale)/T.sum(vM*T.exp(I-scale), axis=1, keepdims=True)
        return s

def mixture_model(random_seed=1234):
    """Sample mixture model to use in benchmarks"""
    np.random.seed(1234)
    size = 1000
    w_true = np.array([0.35, 0.4, 0.25])
    mu_true = np.array([0., 2., 5.])
    sigma = np.array([0.5, 0.5, 1.])
    component = np.random.choice(mu_true.size, size=size, p=w_true)
    x = np.random.normal(mu_true[component], sigma[component], size=size)

    with pm.Model() as model:
        w = pm.Dirichlet('w', a=np.ones_like(w_true))
        mu = pm.Normal('mu', mu=0., sd=10., shape=w_true.shape)
        enforce_order = pm.Potential('enforce_order', tt.switch(mu[0] - mu[1] <= 0, 0., -np.inf) +
                                                      tt.switch(mu[1] - mu[2] <= 0, 0., -np.inf))
        tau = pm.Gamma('tau', alpha=1., beta=1., shape=w_true.shape)
        pm.NormalMixture('x_obs', w=w, mu=mu, tau=tau, observed=x)

    # Initialization can be poorly specified, this is a hack to make it work
    start = {
        'mu': mu_true.copy(),
        'tau_log__': np.log(1. / sigma**2),
        'w_stickbreaking__': np.array([-0.03,  0.44])
    }
    return model, start

def adamgc(cost, params, lr=0.0002, b1=0.1, b2=0.001, e=1e-8, max_magnitude=5.0, infDecay=0.1):
    updates = []
    grads = T.grad(cost, params)
    
    norm = norm_gs(params, grads)
    sqrtnorm = T.sqrt(norm)
    not_finite = T.or_(T.isnan(sqrtnorm), T.isinf(sqrtnorm))
    adj_norm_gs = T.switch(T.ge(sqrtnorm, max_magnitude), max_magnitude / sqrtnorm, 1.)

    i = shared(floatX(0.))
    i_t = i + 1.
    fix1 = 1. - (1. - b1)**i_t
    fix2 = 1. - (1. - b2)**i_t
    lr_t = lr * (T.sqrt(fix2) / fix1)
    for p, g in zip(params, grads):
        g = T.switch(not_finite, infDecay * p, g * adj_norm_gs)
        m = shared(p.get_value() * 0.)
        v = shared(p.get_value() * 0.)
        m_t = (b1 * g) + ((1. - b1) * m) 
        v_t = (b2 * T.sqr(g)) + ((1. - b2) * v)
        g_t = m_t / (T.sqrt(v_t) + e)
        p_t = p - (lr_t * g_t)
        updates.append((m, m_t))
        updates.append((v, v_t))
        updates.append((p, p_t))
    updates.append((i, i_t))
    return updates, norm

def _get_targets(y, log_y_hat, y_mask, y_hat_mask):
    '''
    Returns the target values according to the CTC cost with respect to y_hat.
    Note that this is part of the gradient with respect to the softmax output
    and not with respect to the input of the original softmax function.
    All computations are done in log scale
    '''
    num_classes = log_y_hat.shape[2] - 1
    blanked_y, blanked_y_mask = _add_blanks(
        y=y,
        blank_symbol=num_classes,
        y_mask=y_mask)

    log_alpha, log_beta = _log_forward_backward(blanked_y,
                                                log_y_hat, blanked_y_mask,
                                                y_hat_mask, num_classes)
    # explicitly not using a mask to prevent inf - inf
    y_prob = _class_batch_to_labeling_batch(blanked_y, log_y_hat,
                                            y_hat_mask=None)
    marginals = log_alpha + log_beta - y_prob
    max_marg = marginals.max(2)
    max_marg = T.switch(T.le(max_marg, -np.inf), 0, max_marg)
    log_Z = T.log(T.exp(marginals - max_marg[:,:, None]).sum(2))
    log_Z = log_Z + max_marg
    log_Z = T.switch(T.le(log_Z, -np.inf), 0, log_Z)
    targets = _labeling_batch_to_class_batch(blanked_y,
                                             T.exp(marginals -
                                                   log_Z[:,:, None]),
                                             num_classes + 1)
    return targets

 def __init__(self, rng, f='ReLU', g=lambda x: x, params=None):
     if   f == 'ReLU':
         if hasattr(T.nnet, 'relu'):
             self.f = T.nnet.relu
         else:
             self.f = lambda x: T.switch(x<0,0,x)
         self.g = lambda x: x
     elif f == 'PReLU':
         # Avoids dying ReLU units
         if hasattr(T.nnet, 'relu'):
             self.f = lambda x: T.nnet.relu(x, alpha=0.01)
         else:
             self.f = lambda x: T.switch(x<=0,a*x,x)
         self.g = lambda x: x
     elif f == 'tanh':
         self.f = T.tanh
         self.g = T.arctanh
     elif f == 'sigmoid':
         self.f = T.nnet.sigmoid
         self.g = lambda x: x
     elif f == 'softmax':
         self.f = T.nnet.softmax
         self.g = lambda x: x
     elif f == 'softplus':
         self.f = T.nnet.softplus
         self.g = lambda x: x
     elif f == 'identity':
         self.f = lambda x: x
         self.g = lambda x: x
     else:
         self.f = f
         self.g = g
     
     self.params = [] if params is None else params

    def dlogp(inputs, gradients):
        g_logp, = gradients
        cov, delta = inputs

        g_logp.tag.test_value = floatX(1.)
        n, k = delta.shape

        chol_cov = cholesky(cov)
        diag = tt.nlinalg.diag(chol_cov)
        ok = tt.all(diag > 0)

        chol_cov = tt.switch(ok, chol_cov, tt.fill(chol_cov, 1))
        delta_trans = solve_lower(chol_cov, delta.T).T

        inner = n * tt.eye(k) - tt.dot(delta_trans.T, delta_trans)
        g_cov = solve_upper(chol_cov.T, inner)
        g_cov = solve_upper(chol_cov.T, g_cov.T)

        tau_delta = solve_upper(chol_cov.T, delta_trans.T)
        g_delta = tau_delta.T

        g_cov = tt.switch(ok, g_cov, -np.nan)
        g_delta = tt.switch(ok, g_delta, -np.nan)

        return [-0.5 * g_cov * g_logp, -g_delta * g_logp]

def theano_digitize(x, bins):
    """
    Equivalent to numpy digitize.

    Parameters
    ----------
    x : Theano tensor or array_like
        The array or matrix to be digitized
    bins : array_like
        The bins with which x should be digitized

    Returns
    -------
    A Theano tensor
        The indices of the bins to which each value in input array belongs.
    """
    binned = T.zeros_like(x) + len(bins)
    for i in range(len(bins)):
        bin=bins[i]
        if i == 0:
            binned=T.switch(T.lt(x,bin),i,binned)
        else:
            ineq = T.and_(T.ge(x,bins[i-1]),T.lt(x,bin))
            binned=T.switch(ineq,i,binned)
    binned=T.switch(T.isnan(x), len(bins), binned)
    return binned

    def theano_sentence_prediction(self, Sentence, Chars, WordLengths):

        input_lstm_res_f = self.input_lstm_forward_layer.function(Sentence, Chars, WordLengths)
        input_lstm_res_b = self.input_lstm_backward_layer.function(Sentence, Chars, WordLengths)
        input_combined = T.concatenate((input_lstm_res_f, input_lstm_res_b), axis=1)

        #Make pairwise features. This is really just "tensor product with concatenation instead of multiplication". Is there a command for that?
        full_matrix, _ = theano.scan(fn=self.__pairwise_features,
                                  outputs_info=None,
                                  sequences=input_combined,
                                  non_sequences=[input_combined, Sentence.shape[0]])

        if len(self.lstm_layers) > 0 and self.lstm_layers[0].training:
            srng = RandomStreams(seed=12345)
            full_matrix = T.switch(srng.binomial(size=(Sentence.shape[0], Sentence.shape[0]+1, self.hidden_dimension*4), p=0.5), full_matrix, 0)
        else:
            full_matrix = 0.5 * full_matrix

        full_matrix = self.transition_layer.function(full_matrix)
            
        for layer in self.lstm_layers:
            if layer.training:
                print("hah-train")
                full_matrix = T.switch(srng.binomial(size=(Sentence.shape[0], Sentence.shape[0]+1, self.hidden_dimension*4), p=0.5), full_matrix, 0)
            else:
                print("heh-notrain")
                full_matrix = 0.5 * full_matrix
            
            
            full_matrix = layer.function(full_matrix)
        
        final_matrix = self.output_convolution.function(full_matrix)

        return T.nnet.softmax(final_matrix)