Python backend.dot方法代码示例

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def step(self, x, states):
    h_st, B_U, B_W = states

    if self.consume_less == 'cpu':
      x_t = x[:, :self.output_dim]
      x_h = x[:, self.output_dim: 2 * self.output_dim]
    elif self.consume_less == 'mem':
      x_t = K.dot(x * B_W[0], self.W_t) + self.b_t
      x_h = K.dot(x * B_W[1], self.W_h) + self.b_h
    else:
      raise Exception('Unknown `consume_less` mode.')

    for l in xrange(self.L):
      if l == 0:
        t = self.inner_activation(x_t + K.dot(h_st * B_U[0], self.U_ts[l]) + self.b_ts[l])
        h = self.activation(x_h + K.dot(h_st * B_U[1], self.U_hs[l]) + self.b_hs[l])
      else:
        t = self.inner_activation(K.dot(h_st * B_U[0], self.U_ts[l]) + self.b_ts[l])
        h = self.activation(K.dot(h_st * B_U[1], self.U_hs[l]) + self.b_hs[l])
      h_st = h * t + h_st * (1 - t)

    return h_st, [h_st] 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def step(self, x, states):   
        h = states[0]
        # states[1] necessary?

        # equals K.dot(X, self._W1) + self._b2 with X.shape=[bs, T, input_dim]
        total_x_prod = states[-1]
        # comes from the constants (equals the input sequence)
        X = states[-2]
        
        # expand dims to add the vector which is only valid for this time step
        # to total_x_prod which is valid for all time steps
        hw = K.expand_dims(K.dot(h, self._W2), 1)
        additive_atn = total_x_prod + hw
        attention = K.softmax(K.dot(additive_atn, self._V), axis=1)
        x_weighted = K.sum(attention * X, [1])

        x = K.dot(K.concatenate([x, x_weighted], 1), self._W3) + self._b3
        
        h, new_states = self.layer.cell.call(x, states[:-2])
        
        return h, new_states 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def call(self, x, mask=None):
        # computes a probability distribution over the timesteps
        # uses 'max trick' for numerical stability
        # reshape is done to avoid issue with Tensorflow
        # and 1-dimensional weights
        logits = K.dot(x, self.W)
        x_shape = K.shape(x)
        logits = K.reshape(logits, (x_shape[0], x_shape[1]))
        ai = K.exp(logits - K.max(logits, axis=-1, keepdims=True))

        # masked timesteps have zero weight
        if mask is not None:
            mask = K.cast(mask, K.floatx())
            ai = ai * mask
        att_weights = ai / (K.sum(ai, axis=1, keepdims=True) + K.epsilon())
        weighted_input = x * K.expand_dims(att_weights)
        result = K.sum(weighted_input, axis=1)
        if self.return_attention:
            return [result, att_weights]
        return result 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def call(self , x, mask=None):
        
        e1=x[0].T
        e2=x[1].T
        
        batch_size = K.shape(x[0])[0]
        sim = []
        V_out = K.dot(self.V, K.concatenate([e1,e2],axis=0))     

        for i in range(self.k): 
            temp = K.batch_dot(K.dot(e1.T,self.W[i,:,:]),e2.T,axes=1)
            sim.append(temp)
        sim=K.reshape(sim,(self.k,batch_size))

        tensor_bi_product = self.activation(V_out+sim)
        tensor_bi_product = K.dot(self.U.T, tensor_bi_product).T

        return tensor_bi_product 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def step(self, x, states):
		u_tm1 = states[0]
		B_U = states[3]
		B_W = states[4]

		bv_t = self.bv + K.dot(u_tm1, self.Wuv)
		bh_t = self.bh + K.dot(u_tm1, self.Wuh)

		if self.consume_less == 'cpu':
			h = x
		else:
			h = self.b + K.dot(x * B_W, self.W)

		u_t = self.activation(h + K.dot(u_tm1 * B_U, self.U))

		return x, [u_t, bv_t, bh_t] 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def step(self, x, states):
		h_tm1 = states[0]
		c_tm1 = states[1]

		x_t = self.activation(K.dot(h_tm1, self.A) + self.ba)
		z = K.dot(x_t, self.W) + K.dot(h_tm1, self.U) + self.b


		z0 = z[:, :self.input_dim]
		z1 = z[:, self.input_dim: 2 * self.input_dim]
		z2 = z[:, 2 * self.input_dim: 3 * self.input_dim]
		z3 = z[:, 3 * self.input_dim:]

		i = self.inner_activation(z0)
		f = self.inner_activation(z1)
		c = f * c_tm1 + i * self.activation(z2)
		o = self.inner_activation(z3)

		h = o * self.activation(c)

		return x_t, [h, c] 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def sample_h_given_x(self, x):
		h_pre = K.dot(x, self.Wrbm) + self.bh	
		h_sigm = self.activation(self.scaling_h_given_x * h_pre)

		# drop out noise
		#if(0.0 < self.p < 1.0):
		#	noise_shape = self._get_noise_shape(h_sigm)
		#	h_sigm = K.in_train_phase(K.dropout(h_sigm, self.p, noise_shape), h_sigm)
		
		if(self.hidden_unit_type == 'binary'):
			h_samp = K.random_binomial(shape=h_sigm.shape, p=h_sigm)
	        # random sample
	        #   \hat{h} = 1,      if p(h=1|x) > uniform(0, 1)
	        #             0,      otherwise
		elif(self.hidden_unit_type == 'nrlu'):
			h_samp = nrlu(h_pre)
		else:
			h_samp = h_sigm

		if(0.0 < self.p < 1.0):
			noise_shape = self._get_noise_shape(h_samp)
			h_samp = K.in_train_phase(K.dropout(h_samp, self.p, noise_shape), h_samp)

		return h_samp, h_pre, h_sigm 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def reading(memory_t, weight_t):
    """
    Reading memory.
    :param memory_t: the $N \times M$ memory matrix at time $t$, where $N$
    is the number of memory locations, and $M$ is the vector size at each
    location.
    :param weight_t: $w_t$ is a vector of weightings over the $N$ locations
    emitted by a reading head at time $t$.

    Since all weightings are normalized, the $N$ elements $w_t(i)$ of
    $\textbf{w}_t$ obey the following constraints:
    $$\sum_{i=1}^{N} w_t(i) = 1, 0 \le w_t(i) \le 1,\forall i$$

    The length $M$ read vector $r_t$ returned by the head is defined as a
    convex combination of the row-vectors $M_t(i)$ in memory:
    $$\textbf{r}_t \leftarrow \sum_{i=1}^{N}w_t(i)\textbf{M}_t(i)$$
    :return: the content reading from memory.
    """
    r_t = K.dot(memory_t, weight_t)
    return r_t 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def call(self, inputs):
        """
        In Keras, there are two way to do matrix multiplication (dot product)
        1) K.dot : AxB -> when A has batchsize and B doesn't, use K.dot
        2) tf.matmul: AxB -> when A and B both have batchsize, use tf.matmul
        
        Error example: Use tf.matmul when A has batchsize (3 dim) and B doesn't (2 dim)
        ValueError: Shape must be rank 2 but is rank 3 for 'net_vlad_1/MatMul' (op: 'MatMul') with input shapes: [?,21,64], [64,3]
        
        tf.matmul might still work when the dim of A is (?,64), but this is too confusing.
        Just follow the above rules.
        """
        gates = K.dot(inputs, self.gating_weights)
        gates += self.gating_biases
        gates = tf.sigmoid(gates)

        activation = tf.multiply(inputs,gates)
        return activation 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def call(self, x, mask=None):
        # size of x :[batch_size, sel_len, attention_dim]
        # size of u :[batch_size, attention_dim]
        # uit = tanh(xW+b)
        uit = K.tanh(K.bias_add(K.dot(x, self.W), self.b))
        ait = K.dot(uit, self.u)
        ait = K.squeeze(ait, -1)

        ait = K.exp(ait)

        if mask is not None:
            # Cast the mask to floatX to avoid float64 upcasting in theano
            ait *= K.cast(mask, K.floatx())
        ait /= K.cast(K.sum(ait, axis=1, keepdims=True) + K.epsilon(), K.floatx())
        ait = K.expand_dims(ait)
        weighted_input = x * ait
        output = K.sum(weighted_input, axis=1)

        return output 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def devise_ranking_loss(embedding, margin = 0.1):
    """ The ranking loss used by DeViSE.

    # Arguments:

    - embedding: 2-d numpy array whose rows are class embeddings.

    - margin: margin for the ranking loss.

    # Returns:
        a Keras loss function taking y_true and y_pred as inputs and returning a loss tensor.
    """
    
    def _loss(y_true, y_pred):
        embedding_t = K.constant(embedding.T)
        true_sim = K.sum(y_true * y_pred, axis = -1)
        other_sim = K.dot(y_pred, embedding_t)
        return K.sum(K.relu(margin - true_sim[:,None] + other_sim), axis = -1) - margin
    
    return _loss 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def gram_matrix(x):
	"""
	Computes the outer-product of the input tensor x.

	Input
	-----
	- x: input tensor of shape (C x H x W)

	Returns
	-------
	- x . x^T

	Note that this can be computed efficiently if x is reshaped
	as a tensor of shape (C x H*W).
	"""
	# assert K.ndim(x) == 3
	if K.image_dim_ordering() == 'th':
		features = K.batch_flatten(x)
	else:
		features = K.batch_flatten(K.permute_dimensions(x, (2, 0, 1)))
	return K.dot(features, K.transpose(features)) 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def mask_attention_if_needed(self, dot_product):
        """
        Makes sure that (when enabled) each position
        (of a decoder's self-attention) cannot attend to subsequent positions.
        This is achieved by assigning -inf (or some large negative number)
        to all invalid connections. Later softmax will turn them into zeros.
        We need this to guarantee that decoder's predictions are based
        on what has happened before the position, not after.
        The method does nothing if masking is turned off.
        :param dot_product: scaled dot-product of Q and K after reshaping them
        to 3D tensors (batch * num_heads, rows, cols)
        """
        if not self.use_masking:
            return dot_product
        last_dims = K.int_shape(dot_product)[-2:]
        low_triangle_ones = (
            np.tril(np.ones(last_dims))
            # to ensure proper broadcasting
            .reshape((1,) + last_dims))
        inverse_low_triangle = 1 - low_triangle_ones
        close_to_negative_inf = -1e9
        result = (
            K.constant(low_triangle_ones, dtype=K.floatx()) * dot_product +
            K.constant(close_to_negative_inf * inverse_low_triangle))
        return result 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def call(self, inputs, **kwargs):
        if not (isinstance(inputs, list) and len(inputs) == 2):
            raise ValueError(
                'You can call this layer only with a list of two tensors '
                '(for keys/values and queries)')
        key_values_input, query_input = inputs
        _, value_seq_len, d_model = K.int_shape(key_values_input)
        query_seq_len = K.int_shape(inputs[1])[-2]
        # The first thing we need to do is to perform affine transformations
        # of the inputs to get the Queries, the Keys and the Values.
        kv = K.dot(K.reshape(key_values_input, [-1, d_model]), self.kv_weights)
        # splitting the keys, the values and the queries before further
        # processing
        pre_k, pre_v = [
            K.reshape(
                # K.slice(kv, (0, i * d_model), (-1, d_model)),
                kv[:, i * d_model: (i + 1) * d_model],
                (-1, value_seq_len,
                 self.num_heads, d_model // self.num_heads))
            for i in range(2)]
        pre_q = K.reshape(
            K.dot(K.reshape(query_input, [-1, d_model]), self.q_weights),
            (-1, query_seq_len, self.num_heads, d_model // self.num_heads))
        return self.attention(pre_q, pre_v, pre_k, query_seq_len, d_model,
                              training=kwargs.get('training')) 

# 需要导入模块: from keras import backend [as 别名]
# 或者: from keras.backend import dot [as 别名]
def gram_matrix(x):
    features = K.batch_flatten(K.permute_dimensions(x, (2, 0, 1)))
    gram = K.dot(features, K.transpose(features))
    return gram