Python nn_ops.xw_plus_b函数代码示例

 def f(inp, hidden_weight, hidden_bias, softmax_weight, softmax_bias):
   features = nn_ops.relu(
       nn_ops.xw_plus_b(inp, hidden_weight, hidden_bias), name="features")
   logits = nn_ops.xw_plus_b(
       features, softmax_weight, softmax_bias, name="logits")
   labels = constant_op.constant(
       label_data.tolist(),
       shape=[batch, classes],
       dtype=dtypes.float64,
       name="labels")
   cost = nn_ops.softmax_cross_entropy_with_logits(
       labels=labels, logits=logits, name="cost")
   return cost

 def extract_argmax_and_embed(prev, _):
   """Loop_function that extracts the symbol from prev and embeds it."""
   if output_projection is not None:
     prev = nn_ops.xw_plus_b(
         prev, output_projection[0], output_projection[1])
   prev_symbol = array_ops.stop_gradient(math_ops.argmax(prev, 1))
   return embedding_ops.embedding_lookup(embedding, prev_symbol)

def sequence_softmax(inputs, noutput, scope=None, name=None, linear_name=None):
  """Run a softmax layer over all the time steps of an input sequence.

  Args:
    inputs: (length, batch_size, depth) tensor
    noutput: output depth
    scope: optional scope name
    name: optional name for output tensor
    linear_name: name for linear (pre-softmax) output

  Returns:
    A tensor of size (length, batch_size, noutput).

  """
  length, _, ninputs = _shape(inputs)
  inputs_u = array_ops.unstack(inputs)
  output_u = []
  with variable_scope.variable_scope(scope, "SequenceSoftmax", [inputs]):
    initial_w = random_ops.truncated_normal([0 + ninputs, noutput], stddev=0.1)
    initial_b = constant_op.constant(0.1, shape=[noutput])
    w = variables.model_variable("weights", initializer=initial_w)
    b = variables.model_variable("biases", initializer=initial_b)
    for i in xrange(length):
      with variable_scope.variable_scope(scope, "SequenceSoftmaxStep",
                                         [inputs_u[i]]):
        # TODO(tmb) consider using slim.fully_connected(...,
        # activation_fn=tf.nn.softmax)
        linear = nn_ops.xw_plus_b(inputs_u[i], w, b, name=linear_name)
        output = nn_ops.softmax(linear)
        output_u += [output]
    outputs = array_ops.stack(output_u, name=name)
  return outputs

  def loop_function(prev, i, log_beam_probs, beam_path, beam_symbols):
    if output_projection is not None:
      prev = nn_ops.xw_plus_b(
          prev, output_projection[0], output_projection[1])
    # prev= prev.get_shape().with_rank(2)[1]

    probs  = tf.log(tf.nn.softmax(prev))

    if i > 1:

        probs = tf.reshape(probs + log_beam_probs[-1],
                               [-1, beam_size * num_symbols])

    best_probs, indices = tf.nn.top_k(probs, beam_size)
    indices = tf.stop_gradient(tf.squeeze(tf.reshape(indices, [-1, 1])))
    best_probs = tf.stop_gradient(tf.reshape(best_probs, [-1, 1]))

    symbols = indices % num_symbols # Which word in vocabulary.
    beam_parent = indices // num_symbols # Which hypothesis it came from.


    beam_symbols.append(symbols)
    beam_path.append(beam_parent)
    log_beam_probs.append(best_probs)

    # Note that gradients will not propagate through the second parameter of
    # embedding_lookup.

    emb_prev = embedding_ops.embedding_lookup(embedding, symbols)
    emb_prev  = tf.reshape(emb_prev,[beam_size,embedding_size])
    # emb_prev = embedding_ops.embedding_lookup(embedding, symbols)
    if not update_embedding:
      emb_prev = array_ops.stop_gradient(emb_prev)
    return emb_prev

def beam_rnn_decoder(decoder_inputs, initial_state, cell, loop_function=None,
                scope=None,output_projection=None, beam_size=10):
  """RNN decoder for the sequence-to-sequence model.

  Args:
    decoder_inputs: A list of 2D Tensors [batch_size x input_size].
    initial_state: 2D Tensor with shape [batch_size x cell.state_size].
    cell: rnn_cell.RNNCell defining the cell function and size.
    loop_function: If not None, this function will be applied to the i-th output
      in order to generate the i+1-st input, and decoder_inputs will be ignored,
      except for the first element ("GO" symbol). This can be used for decoding,
      but also for training to emulate http://arxiv.org/abs/1506.03099.
      Signature -- loop_function(prev, i) = next
        * prev is a 2D Tensor of shape [batch_size x output_size],
        * i is an integer, the step number (when advanced control is needed),
        * next is a 2D Tensor of shape [batch_size x input_size].
    scope: VariableScope for the created subgraph; defaults to "rnn_decoder".

  Returns:
    A tuple of the form (outputs, state), where:
      outputs: A list of the same length as decoder_inputs of 2D Tensors with
        shape [batch_size x output_size] containing generated outputs.
      state: The state of each cell at the final time-step.
        It is a 2D Tensor of shape [batch_size x cell.state_size].
        (Note that in some cases, like basic RNN cell or GRU cell, outputs and
         states can be the same. They are different for LSTM cells though.)
  """
  with variable_scope.variable_scope(scope or "rnn_decoder"):
    state = initial_state
    outputs = []
    prev = None
    log_beam_probs, beam_path, beam_symbols = [],[],[]
    state_size = int(initial_state.get_shape().with_rank(2)[1])

    for i, inp in enumerate(decoder_inputs):
      if loop_function is not None and prev is not None:
        with variable_scope.variable_scope("loop_function", reuse=True):
          inp = loop_function(prev, i,log_beam_probs, beam_path, beam_symbols)
      if i > 0:
        variable_scope.get_variable_scope().reuse_variables()

      input_size = inp.get_shape().with_rank(2)[1]
      print input_size
      x = inp
      output, state = cell(x, state)

      if loop_function is not None:
        prev = output
      if  i ==0:
          states =[]
          for kk in range(beam_size):
                states.append(state)
          state = tf.reshape(tf.concat(0, states), [-1, state_size])

      outputs.append(tf.argmax(nn_ops.xw_plus_b(
          output, output_projection[0], output_projection[1]), dimension=1))
  return outputs, state, tf.reshape(tf.concat(0, beam_path),[-1,beam_size]), tf.reshape(tf.concat(0, beam_symbols),[-1,beam_size])

 def loop_function(prev, _):
     if output_projection is not None:
         prev = nn_ops.xw_plus_b(prev, output_projection[0], output_projection[1])
     prev_symbol = math_ops.argmax(prev, 1)
     # Note that gradients will not propagate through the second parameter of
     # embedding_lookup.
     emb_prev = embedding_ops.embedding_lookup(embedding, prev_symbol)
     if not update_embedding:
         emb_prev = array_ops.stop_gradient(emb_prev)
     return emb_prev

   def loop_function(prev,_):

      if output_projection is not None:
         prev = nn_ops.xw_plus_b ( prev, output_projection[0], output_projection[1] )
      
      tf_prev_symbol = batch_sample_with_temperature(prev)
      emb_prev = embedding_ops.embedding_lookup(embedding, tf_prev_symbol)

      if not update_embedding :
         emb_prev = array_ops.stop_gradient(emb_prev)
      return emb_prev

  def _BuildAndTestMiniMNIST(self, param_index, tag):
    # Fix seed to avoid occasional flakiness
    np.random.seed(6)

    # Hyperparameters
    batch = 3
    inputs = 16
    features = 32
    classes = 10

    # Define the parameters
    inp_data = np.random.random_sample(inputs * batch)
    hidden_weight_data = np.random.randn(inputs * features) / np.sqrt(inputs)
    hidden_bias_data = np.random.random_sample(features)
    sm_weight_data = np.random.randn(features * classes) / np.sqrt(features)
    sm_bias_data = np.random.random_sample(classes)

    # special care for labels since they need to be normalized per batch
    label_data = np.random.random(batch * classes).reshape((batch, classes))
    s = label_data.sum(axis=1)
    label_data /= s[:, None]

    with self.session(use_gpu=True):
      # We treat the inputs as "parameters" here
      inp = constant_op.constant(
          inp_data.tolist(),
          shape=[batch, inputs],
          dtype=dtypes.float64,
          name="inp")
      hidden_weight = constant_op.constant(
          hidden_weight_data.tolist(),
          shape=[inputs, features],
          dtype=dtypes.float64,
          name="hidden_weight")
      hidden_bias = constant_op.constant(
          hidden_bias_data.tolist(),
          shape=[features],
          dtype=dtypes.float64,
          name="hidden_bias")
      softmax_weight = constant_op.constant(
          sm_weight_data.tolist(),
          shape=[features, classes],
          dtype=dtypes.float64,
          name="softmax_weight")
      softmax_bias = constant_op.constant(
          sm_bias_data.tolist(),
          shape=[classes],
          dtype=dtypes.float64,
          name="softmax_bias")

      # List all the parameter so that we can test them one at a time
      all_params = [
          inp, hidden_weight, hidden_bias, softmax_weight, softmax_bias
      ]
      param_sizes = [
          [batch, inputs],  # inp
          [inputs, features],  # hidden_weight,
          [features],  # hidden_bias
          [features, classes],  # softmax_weight,
          [classes]
      ]  # softmax_bias

      # Now, Building MNIST
      features = nn_ops.relu(
          nn_ops.xw_plus_b(inp, hidden_weight, hidden_bias), name="features")
      logits = nn_ops.xw_plus_b(
          features, softmax_weight, softmax_bias, name="logits")
      labels = constant_op.constant(
          label_data.tolist(),
          shape=[batch, classes],
          dtype=dtypes.float64,
          name="labels")
      cost = nn_ops.softmax_cross_entropy_with_logits(
          labels=labels, logits=logits, name="cost")

      # Test the gradients.
      err = gradient_checker.compute_gradient_error(
          all_params[param_index],
          param_sizes[param_index],
          cost, [batch],
          delta=1e-5)

    tf_logging.info("Mini MNIST: %s gradient error = %g", tag, err)
    return err

#.........这里部分代码省略.........
    output_size = cell.output_size

  with variable_scope.variable_scope(scope or "attention_decoder"):
    batch_size = array_ops.shape(decoder_inputs[0])[0]  # Needed for reshaping.
    attn_length = attention_states.get_shape()[1].value
    attn_size = attention_states.get_shape()[2].value

    # To calculate W1 * h_t we use a 1-by-1 convolution, need to reshape before.
    hidden = array_ops.reshape(
        attention_states, [-1, attn_length, 1, attn_size])
    hidden_features = []
    v = []
    attention_vec_size = attn_size  # Size of query vectors for attention.
    for a in xrange(num_heads):
      k = variable_scope.get_variable("AttnW_%d" % a,
                                      [1, 1, attn_size, attention_vec_size])
      hidden_features.append(nn_ops.conv2d(hidden, k, [1, 1, 1, 1], "SAME"))
      v.append(variable_scope.get_variable("AttnV_%d" % a,
                                           [attention_vec_size]))

    print "Initial_state"

    state_size =  int(initial_state.get_shape().with_rank(2)[1])
    states =[]
    for kk in range(1):
        states.append(initial_state)
    state = tf.reshape(tf.concat(0, states), [-1, state_size])
    def attention(query):
      """Put attention masks on hidden using hidden_features and query."""
      ds = []  # Results of attention reads will be stored here.
      for a in xrange(num_heads):
        with variable_scope.variable_scope("Attention_%d" % a):
          y = linear(query, attention_vec_size, True)
          y = array_ops.reshape(y, [-1, 1, 1, attention_vec_size])
          # Attention mask is a softmax of v^T * tanh(...).
          s = math_ops.reduce_sum(
              v[a] * math_ops.tanh(hidden_features[a] + y), [2, 3])
          a = nn_ops.softmax(s)
          # Now calculate the attention-weighted vector d.
          d = math_ops.reduce_sum(
              array_ops.reshape(a, [-1, attn_length, 1, 1]) * hidden,
              [1, 2])
          # for c in range(ct):
          ds.append(array_ops.reshape(d, [-1, attn_size]))
      return ds

    outputs = []
    prev = None
    batch_attn_size = array_ops.pack([batch_size, attn_size])
    attns = [array_ops.zeros(batch_attn_size, dtype=dtype)
             for _ in xrange(num_heads)]
    for a in attns:  # Ensure the second shape of attention vectors is set.
      a.set_shape([None, attn_size])

    if initial_state_attention:
       attns = []
       attns.append(attention(initial_state))
       tmp = tf.reshape(tf.concat(0, attns), [-1, attn_size])
       attns = []
       attns.append(tmp)

    log_beam_probs, beam_path, beam_symbols = [],[],[]
    for i, inp in enumerate(decoder_inputs):

      if i > 0:
        variable_scope.get_variable_scope().reuse_variables()
      # If loop_function is set, we use it instead of decoder_inputs.
      if loop_function is not None :
        with variable_scope.variable_scope("loop_function", reuse=True):
            if prev is not None:
                inp = loop_function(prev, i,log_beam_probs, beam_path, beam_symbols)

      input_size = inp.get_shape().with_rank(2)[1]
      x = linear([inp] + attns, input_size, True)
      cell_output, state = cell(x, state)

      # Run the attention mechanism.
      if i == 0 and initial_state_attention:
        with variable_scope.variable_scope(variable_scope.get_variable_scope(),
                                           reuse=True):
          attns = attention(state)
      else:
          attns = attention(state)

      with variable_scope.variable_scope("AttnOutputProjection"):
        output = linear([cell_output] + attns, output_size, True)
      if loop_function is not None:
        prev = output
      if  i ==0:
          states =[]
          for kk in range(beam_size):
                states.append(state)
          state = tf.reshape(tf.concat(0, states), [-1, state_size])
          with variable_scope.variable_scope(variable_scope.get_variable_scope(), reuse=True):
                attns = attention(state)

      outputs.append(tf.argmax(nn_ops.xw_plus_b(
          output, output_projection[0], output_projection[1]), dimension=1))

  return outputs, state, tf.reshape(tf.concat(0, beam_path),[-1,beam_size]), tf.reshape(tf.concat(0, beam_symbols),[-1,beam_size])