提交 3e195d86 编写于 作者: Y ying

add wrapper for multihead_attention.

上级 430fdc52
......@@ -22,13 +22,38 @@ from ..param_attr import ParamAttr
from tensor import concat
__all__ = [
'fc', 'embedding', 'dynamic_lstm', 'gru_unit', 'linear_chain_crf',
'crf_decoding', 'cos_sim', 'cross_entropy', 'square_error_cost', 'accuracy',
'chunk_eval', 'sequence_conv', 'conv2d', 'sequence_pool', 'pool2d',
'batch_norm', 'beam_search_decode', 'conv2d_transpose', 'sequence_expand',
'lstm_unit', 'reduce_sum', 'reduce_mean', 'reduce_max', 'reduce_min',
'sequence_first_step', 'sequence_last_step', 'dropout', 'split',
'l2_normalize', 'matmul', 'warpctc', 'sequence_reshape'
'fc',
'embedding',
'dynamic_lstm',
'gru_unit',
'linear_chain_crf',
'crf_decoding',
'cos_sim',
'cross_entropy',
'square_error_cost',
'accuracy',
'chunk_eval',
'sequence_conv',
'conv2d',
'sequence_pool',
'pool2d',
'batch_norm',
'beam_search_decode',
'conv2d_transpose',
'sequence_expand',
'lstm_unit',
'reduce_sum',
'reduce_mean',
'reduce_max',
'reduce_min',
'sequence_first_step',
'sequence_last_step',
'dropout',
'split',
'l2_normalize',
'matmul',
'warpctc',
'sequence_reshape',
]
......@@ -43,14 +68,14 @@ def fc(input,
**Fully Connected Layer**
The fully connected layer can take multiple tensors as its inputs. It
creates a variable (one for each input tensor) called weights for each input
tensor, which represents a fully connected weight matrix from each input
unit to each output unit. The fully connected layer multiplies each input
tensor with its coresponding weight to produce an output Tensor. If
multiple input tensors are given, the results of multiple multiplications
will be sumed up. If bias_attr is not None, a biases variable will be
created and added to the output. Finally, if activation is not None,
it will be applied to the output as well.
creates a variable (one for each input tensor) called weights for each
input tensor, which represents a fully connected weight matrix from
each input unit to each output unit. The fully connected layer
multiplies each input tensor with its coresponding weight to produce
an output Tensor. If multiple input tensors are given, the results of
multiple multiplications will be sumed up. If bias_attr is not None,
a biases variable will be created and added to the output. Finally,
if activation is not None, it will be applied to the output as well.
This process can be formulated as follows:
......@@ -1813,11 +1838,11 @@ def matmul(x, y, transpose_x=False, transpose_y=False, name=None):
- If both are 2-D, they are multiplied like conventional matrices.
- If either is n-D, it is treated as a stack of matrices residing in the
last two dimensions and a batched matrix multiply supporting broadcast
last two dimensions and a batched matrix multiply supporting broadcast
applies on the two tensors.
Also note that if the raw tensor :math:`x` or :math:`y` is rank-1 and
nontransposed, the prepended or appended dimension :math:`1` will be
Also note that if the raw tensor :math:`x` or :math:`y` is rank-1 and
nontransposed, the prepended or appended dimension :math:`1` will be
removed after matrix multiplication.
Args:
......
......@@ -46,10 +46,21 @@ __activations__ = [
]
__all__ = [
'mean', 'mul', 'reshape', 'scale', 'transpose',
'sigmoid_cross_entropy_with_logits', 'elementwise_add', 'elementwise_div',
'elementwise_sub', 'elementwise_mul', 'elementwise_max', 'elementwise_min',
'clip', 'clip_by_norm', 'sequence_softmax'
'mean',
'mul',
'reshape',
'scale',
'transpose',
'sigmoid_cross_entropy_with_logits',
'elementwise_add',
'elementwise_div',
'elementwise_sub',
'elementwise_mul',
'elementwise_max',
'elementwise_min',
'clip',
'clip_by_norm',
'sequence_softmax',
] + __activations__
for _OP in set(__all__):
......
......@@ -127,21 +127,21 @@ def sequence_conv_pool(input,
def glu(input, dim=-1):
"""
The gated linear unit composed by split, sigmoid activation and elementwise
multiplication. Specifically, Split the input into two equal sized parts
:math:`a` and :math:`b` along the given dimension and then compute as
The gated linear unit composed by split, sigmoid activation and elementwise
multiplication. Specifically, Split the input into two equal sized parts
:math:`a` and :math:`b` along the given dimension and then compute as
following:
.. math::
{GLU}(a, b)= a \otimes \sigma(b)
Refer to `Language Modeling with Gated Convolutional Networks
Refer to `Language Modeling with Gated Convolutional Networks
<https://arxiv.org/pdf/1612.08083.pdf>`_.
Args:
input (Variable): The input variable which is a Tensor or LoDTensor.
dim (int): The dimension along which to split. If :math:`dim < 0`, the
dim (int): The dimension along which to split. If :math:`dim < 0`, the
dimension to split along is :math:`rank(input) + dim`.
Returns:
......@@ -160,53 +160,105 @@ def glu(input, dim=-1):
return out
def dot_product_attention(querys, keys, values):
def scaled_dot_product_attention(queries,
keys,
values,
num_heads,
dropout_rate=0.):
"""
The dot-product attention.
Attention mechanism can be seen as mapping a query and a set of key-value
pairs to an output. The output is computed as a weighted sum of the values,
where the weight assigned to each value is computed by a compatibility
function (dot-product here) of the query with the corresponding key.
The dot-product attention can be implemented through (batch) matrix
Attention mechanism can be seen as mapping a query and a set of
key-value pairs to an output. The output is computed as a weighted sum
of the values, where the weight assigned to each value is computed by a
compatibility function (dot-product here) of the query with the
corresponding key.
The dot-product attention can be implemented through (batch) matrix
multipication as follows:
.. math::
Attention(Q, K, V)= softmax(QK^\mathrm{T})V
Refer to `Attention Is All You Need
Refer to `Attention Is All You Need
<https://arxiv.org/pdf/1706.03762.pdf>`_.
Note that batch data containing sequences with different lengths is not
Note that batch data containing sequences with different lengths is not
supported by this because of the (batch) matrix multipication.
Args:
query (Variable): The input variable which is a Tensor or LoDTensor.
query (Variable): The input variable which is a Tensor or
LoDTensor.
key (Variable): The input variable which is a Tensor or LoDTensor.
value (Variable): The input variable which is a Tensor or LoDTensor.
value (Variable): The input variable which is a Tensor or
LoDTensor.
Returns:
tuple: The Tensor variables representing the output and attention scores.
tuple: The Tensor variables representing the output and attention
scores.
Examples:
.. code-block:: python
# Suppose q, k, v are tensor variables with the following shape:
# q: [3, 5, 9], k: [3, 6, 9], v: [3, 6, 10]
# Suppose q, k, v are tensor variables with the following
# shape: q: [3, 5, 9], k: [3, 6, 9], v: [3, 6, 10]
out, attn_scores = fluid.nets.dot_product_attention(q, k, v)
out.shape # [3, 5, 10]
attn_scores.shape # [3, 5, 6]
"""
assert keys.shape[-2] == values.shape[
-2], 'The shapes of keys and values mismatch.'
assert querys.shape[-1] == keys.shape[
-1], 'The shapes of querys and keys mismatch.'
product = layers.matmul(x=querys, y=keys, transpose_y=True)
if not (len(queries.shape) == len(keys.shape) == len(values.shape) == 3):
raise ValueError(
"Inputs quries, keys and values should all be 3-D tensors.")
if queries.shape[-1] != keys.shape[-1]:
raise ValueError(
"The hidden size of queries and keys should be the same.")
if keys.shape[-2] != values.shape[-2]:
raise ValueError(
"The max sequence length in query batch and in key batch "
"should be the same.")
if keys.shape[-1] % num_heads != 0:
raise ValueError("The hidden size of keys (%d) must be divisible "
"by the number of attention heads (%d)." %
(keys.shape[-1], num_heads))
if values.shape[-1] % num_heads != 0:
raise ValueError("The hidden size of values (%d) must be divisible "
"by the number of attention heads (%d)." %
(values.shape[-1], num_heads))
def __split_heads(x, num_heads):
"""
Reshape the last dimension of inpunt tensor x so that it becomes two
dimensions.
Args:
x(Tensor): a 3-D input Tensor.
num_heads(int): The number of heads.
Returns:
a Tensor with shape [..., n, m/n]
"""
hidden_size = x.shape[-1]
#
reshaped = layers.reshape(
x=x, shape=x.shape[:-1] + [num_heads, hidden_size // num_heads])
pass
def __combine_heads():
pass
q = __split_heads(quries, num_heads)
k = __split_heads(keys, num_heads)
v = __split_heads(values, num_heads)
key_dim_per_head = keys.shape[-1] // num_heads
scale = key_dim_per_head**-0.5
product = layers.matmul(x=k, y=q, transpose_y=True)
attn_scores = layers.reshape(
x=layers.reshape(
x=product, shape=[-1, product.shape[-1]], act='softmax'),
x=product, shape=[-1, product.shape[-1]], act="softmax"),
shape=product.shape)
out = layers.matmul(attn_scores, values)
return out, attn_scores
context = layers.matmul(attn_scores, values)
return context, attn_scores
# Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserve.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import unittest
import paddle.v2.fluid as fluid
import paddle.v2.fluid.core as core
import numpy as np
import pdb
class TestMultiheadAttention(unittest.TestCase):
def gen_random_input(self):
"""Generate random input data.
"""
# batch_size, max_sequence_length, hidden dimension
self.input_shape = (3, 13, 16)
self.queries = np.random.random(size=self.input_shape).astype("float32")
self.keys = np.random.random(size=self.input_shape).astype("float32")
def set_program(self):
"""Build the test program.
"""
queries = fluid.layers.data(
name="queries",
shape=self.input_shape,
dtype="float32",
append_batch_size=False)
queries.stop_gradient = False
keys = fluid.layers.data(
name="keys",
shape=self.input_shape,
dtype="float32",
append_batch_size=False)
keys.stop_gradient = False
contexts, att_scores = fluid.nets.scaled_dot_product_attention(
queries=queries,
keys=keys,
values=keys,
num_heads=8,
dropout_rate=0.)
out = fluid.layers.reduce_sum(contexts, dim=None)
fluid.backward.append_backward(loss=out)
self.fetch_list = [contexts]
def run_program(self):
"""Run the test program.
"""
places = [core.CPUPlace()]
if core.is_compile_gpu():
places.append(core.CUDAPlace(0))
for place in places:
self.set_inputs(place)
exe = fluid.Executor(place)
output = exe.run(fluid.default_main_program(),
feed=self.inputs,
fetch_list=self.fetch_list,
return_numpy=True)
self.op_output = output
def set_inputs(self, place):
"""Set the randomly generated data to the test program.
"""
self.inputs = {}
queries = fluid.Tensor()
queries.set(self.queries, place)
keys = fluid.Tensor()
keys.set(self.keys, place)
self.inputs["keys"] = keys
self.inputs["values"] = values
def test_multihead_attention(self):
self.gen_random_input()
self.set_program()
pdb.set_trace()
self.run_program()
expect_output = self.l2_normalize(self.data, axis, epsilon)
# check output
self.assertTrue(np.allclose(self.op_output, expect_output, atol=0.001))
if __name__ == '__main__':
unittest.main()
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