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Paddle/python/paddle/fluid/layers/control_flow.py

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# Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
#
# 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 contextlib
from .layer_function_generator import autodoc, templatedoc
from .tensor import assign, fill_constant
from .. import core
from ..framework import Program, Variable, Operator
from ..layer_helper import LayerHelper, unique_name
from ..initializer import force_init_on_cpu
from .ops import logical_and, logical_not, logical_or
import numpy
import warnings
from functools import reduce
__all__ = [
'While',
'Switch',
'increment',
'array_write',
'create_array',
'less_than',
'equal',
'array_read',
'array_length',
'IfElse',
'DynamicRNN',
'StaticRNN',
'reorder_lod_tensor_by_rank',
'ParallelDo',
'Print',
'is_empty',
]
def split_lod_tensor(input, mask, level=0):
"""
This function takes in an input that contains the complete lod information,
and takes in a mask which is used to mask certain parts of the input.
The output is the true branch and the false branch with the mask applied to
the input at a certain level in the tensor. Mainly used in IfElse to split
data into two parts.
Args:
input(tuple|list|None): The input tensor that contains complete
lod information needed to construct the output.
mask(list): A bool column vector which masks the input.
level(int): The specific lod level to split.
Returns:
tuple(Variable, Variable):
The true branch of tensor as per the mask applied to input.
The false branch of tensor as per the mask applied to input.
Examples:
.. code-block:: python
x = fluid.layers.data(name='x', shape=[1])
x.persistable = True
y = fluid.layers.data(name='y', shape=[1])
y.persistable = True
out_true, out_false = fluid.layers.split_lod_tensor(
input=x, mask=y, level=level)
"""
helper = LayerHelper('split_lod_tensor', **locals())
out_true = helper.create_tmp_variable(dtype=input.dtype)
out_false = helper.create_tmp_variable(dtype=input.dtype)
helper.append_op(
type='split_lod_tensor',
inputs={
'X': input,
'Mask': mask,
},
outputs={'OutTrue': out_true,
'OutFalse': out_false},
attrs={'level': level})
return out_true, out_false
def merge_lod_tensor(in_true, in_false, x, mask, level=0):
"""
**merge_lod_tensor**
This function takes in an input :math:`x`, the True branch, the False
branch and a binary :math:`mask`. Using this information, this function
merges the True and False branches of the tensor into a single tensor as
output at a certain lod level indicated by :math:`level`. Used in IfElse
to merge the output if True block and False Block.
Args:
in_true(tuple|list|None): The True branch to be merged.
in_false(tuple|list|None): The False branch to be merged.
x(tuple|list|None): The input tensor that contains complete
lod information needed to construct the output.
mask(list): A bool column vector which masks the input.
level(int): The specific lod level to merge.
Returns:
Variable: The merged output tensor.
Examples:
.. code-block:: python
x = layers.data(
name='x', shape=[1], dtype='float32', stop_gradient=False)
y = layers.data(
name='y', shape=[1], dtype='bool', stop_gradient=False)
level = 0
out_true, out_false = layers.split_lod_tensor(
input=x, mask=y, level=level)
out = layers.merge_lod_tensor(
in_true=out_true, in_false=out_false, mask=y, x=x, level=level)
"""
helper = LayerHelper('merge_lod_tensor', **locals())
out = helper.create_tmp_variable(dtype=in_true.dtype)
helper.append_op(
type='merge_lod_tensor',
inputs={'X': x,
'Mask': mask,
'InTrue': in_true,
'InFalse': in_false},
outputs={'Out': out},
attrs={'level': level})
return out
def Print(input,
first_n=-1,
message=None,
summarize=-1,
print_tensor_name=True,
print_tensor_type=True,
print_tensor_shape=True,
print_tensor_lod=True,
print_phase='both'):
'''
**Print operator**
This creates a print op that will print when a tensor is accessed.
Wraps the tensor passed in so that whenever that a tensor is accessed,
the message `message` is printed, along with the current value of the
tensor `t`.
Args:
input (Variable): A Tensor to print.
summarize (int): Print this number of elements in the tensor, will print
all if left is negative.
message (str): A string message to print as a prefix.
first_n (int): Only log `first_n` number of times.
print_tensor_name (bool): Print the tensor name.
print_tensor_type (bool): Print the tensor type.
print_tensor_shape (bool): Print the tensor shape.
print_tensor_lod (bool): Print the tensor lod.
print_phase (str): Which phase to displace, including 'forward',
'backward' and 'both'. If set to 'backward' or 'both', will
print the gradients of input tensor.
Returns:
Variable: Output tensor, same data with input tensor.
Examples:
.. code-block:: python
value = some_layer(...)
Print(value, summarize=10,
message="The content of some_layer: ")
'''
helper = LayerHelper('print', **locals())
out = helper.create_tmp_variable(dtype=helper.input_dtype())
helper.append_op(
type='print',
inputs={'In': input},
attrs={
'first_n': first_n,
'summarize': summarize,
'message': message or "",
'print_tensor_name': print_tensor_name,
'print_tensor_type': print_tensor_type,
'print_tensor_shape': print_tensor_shape,
'print_tensor_lod': print_tensor_lod,
'print_phase': print_phase.upper()
},
outputs={'Out': out})
return out
class BlockGuard(object):
"""
BlockGuard class.
BlockGuard class is used to create a sub-block in a program by
using the Python `with` keyword.
"""
def __init__(self, main_program):
if not isinstance(main_program, Program):
raise TypeError("BlockGuard takes a program")
self.main_program = main_program
def __enter__(self):
self.main_program.create_block()
def __exit__(self, exc_type, exc_val, exc_tb):
self.main_program.rollback()
if exc_type is not None:
return False # re-raise exception
return True
class ParallelDo(object):
"""
ParallelDo is used to represent multi-thread data parallel processing.
Its vanilla implementation can be shown as the following (:math:`|` means
single thread and :math:`||||` means multiple threads)
.. code-block:: text
In the forward pass
| Split input onto different devices
| Copy parameter onto different devices
|||| Compute forward pass in parallel
| Merge output from different devices
In the backward pass
| Split output@grad onto different devices
|||| Compute backward pass in parallel
| accumulate param@grad from different devices to the first device
| Merge input@grad from different devices
| Copy param@grad to the place of parallel_do_op
Examples:
.. code-block:: python
images = fluid.layers.data(name='pixel', shape=[1, 28, 28], dtype=DTYPE)
label = fluid.layers.data(name='label', shape=[1], dtype='int64')
# ParallelDo version & Single-thread version
if thread_num > 1:
places = fluid.layers.get_places(thread_num)
pd = fluid.layers.ParallelDo(places)
with pd.do():
images = pd.read_input(images)
label = pd.read_input(label)
predict = cnn_model(images)
cost = fluid.layers.cross_entropy(input=predict, label=label)
avg_cost = fluid.layers.mean(x=cost)
pd.write_output(avg_cost)
avg_cost = pd()
avg_cost = fluid.layers.mean(avg_cost)
else:
predict = cnn_model(images)
cost = fluid.layers.cross_entropy(input=predict, label=label)
avg_cost = fluid.layers.mean(x=cost)
.. warning::
It will be soon deprecated, please use ParallelExecutor instead.
"""
def __init__(self, places, use_nccl=False, name=None):
warnings.warn(
"API ParallelDo is deprecated since 0.15.0. Please use ParallelExecutor instead.",
Warning)
self.helper = LayerHelper("parallel_do", name=name)
self.inputs = []
self.places = places
self.outputs = []
self.status = StaticRNN.BEFORE_RNN_BLOCK
self.use_nccl = use_nccl
def do(self):
return BlockGuardWithCompletion(self)
def parent_block(self):
prog = self.helper.main_program
parent_idx = prog.current_block().parent_idx
assert parent_idx >= 0
parent_block = prog.block(parent_idx)
return parent_block
def __call__(self, *args, **kwargs):
if self.status != StaticRNN.AFTER_RNN_BLOCK:
raise ValueError("RNN output can only be retrieved after rnn block")
if len(self.outputs) == 0:
raise ValueError("RNN has no output")
elif len(self.outputs) == 1:
return self.outputs[0]
else:
return self.outputs
def read_input(self, var):
self.inputs.append(var)
return var
def write_output(self, var):
self.outputs.append(var)
def get_parameters(self):
main_program = self.helper.main_program
current_block = main_program.current_block()
parent_block = self.parent_block()
local_inputs = set()
params = list()
for var in self.inputs:
local_inputs.add(var.name)
for op in current_block.ops:
for iname in op.input_names:
for in_var_name in op.input(iname):
if in_var_name not in local_inputs:
params.append(in_var_name)
for oname in op.output_names:
for out_var_name in op.output(oname):
local_inputs.add(out_var_name)
params = list(set(params))
return [parent_block.var(name) for name in params]
def _complete_op(self):
main_program = self.helper.main_program
current_block = main_program.current_block()
parent_block = self.parent_block()
step_scope = parent_block.create_var(
type=core.VarDesc.VarType.STEP_SCOPES)
self.outputs = [
parent_block.create_var(
name=o.name,
shape=o.shape,
dtype=o.dtype,
lod_level=o.lod_level,
persistable=o.persistable,
stop_gradient=o.stop_gradient) for o in self.outputs
]
inputs = [parent_block.var(i.name) for i in self.inputs]
outputs = [parent_block.var(o.name) for o in self.outputs]
parent_block.append_op(
type='parallel_do',
inputs={
'inputs': inputs,
'parameters': self.get_parameters(),
'places': self.places
},
outputs={'outputs': outputs,
'parallel_scopes': [step_scope]},
attrs={'sub_block': current_block,
'use_nccl': self.use_nccl})
class BlockGuardWithCompletion(BlockGuard):
"""
BlockGuardWithCompletion class.
BlockGuardWithCompletion class is used to create an op with a block in a program.
"""
def __init__(self, rnn):
if not (isinstance(rnn, StaticRNN) or isinstance(rnn, ParallelDo)):
raise TypeError(
"BlockGuardWithCompletion takes a StaticRNN or ParallelDo")
super(BlockGuardWithCompletion, self).__init__(rnn.helper.main_program)
self.rnn = rnn
def __enter__(self):
self.rnn.status = StaticRNN.IN_RNN_BLOCK
return super(BlockGuardWithCompletion, self).__enter__()
def __exit__(self, exc_type, exc_val, exc_tb):
if exc_type is not None:
return False
self.rnn.status = StaticRNN.AFTER_RNN_BLOCK
self.rnn._complete_op()
return super(BlockGuardWithCompletion, self).__exit__(exc_type, exc_val,
exc_tb)
class StaticRNNMemoryLink(object):
"""
StaticRNNMemoryLink class.
StaticRNNMemoryLink class is used to create a link between two
memory cells of a StaticRNN.
NOTE: This is a internal data structure of a very low-level API.
Please use StaticRNN instead.
Args:
init(Variable): the initial variable for Memory.
pre_mem(Variable): the memory variable in previous time step.
mem(Variable): the memory variable in current time step.
"""
def __init__(self, init, pre_mem, mem=None):
self.init = init
self.pre_mem = pre_mem
self.mem = mem
class StaticRNN(object):
"""
StaticRNN class.
StaticRNN class is used to create a StaticRNN. The RNN will have its
own parameters like inputs, outputs, memories, status and length.
"""
BEFORE_RNN_BLOCK = 0
IN_RNN_BLOCK = 1
AFTER_RNN_BLOCK = 2
def __init__(self, name=None):
self.helper = LayerHelper("static_rnn", name=name)
self.memories = {} # memory map, from pre_mem.name --> MemoryLink
self.inputs = [] # input variable list in current block
self.outputs = [] # output variable list in parent block
self.status = StaticRNN.BEFORE_RNN_BLOCK # status flag.
# sequence length, since it is a static RNN, sequence length are fixed.
self.seq_len = None
def step(self):
return BlockGuardWithCompletion(self)
def _assert_in_rnn_block_(self, method):
if self.status != StaticRNN.IN_RNN_BLOCK:
raise ValueError("You must invoke {0} in rnn block".format(method))
def memory(self,
init=None,
shape=None,
batch_ref=None,
init_value=0.0,
init_batch_dim_idx=0,
ref_batch_dim_idx=1):
"""
Args:
init: boot memory, if not set, a shape, batch_ref must be provided
shape: shape of the boot memory
batch_ref: batch size reference variable
init_value: the init value of boot memory
init_batch_dim_idx: the index of batch size in init's dimension
ref_batch_dim_idx: the index of batch size in batch_ref's dimension
"""
self._assert_in_rnn_block_('memory')
if init is None:
if shape is None or batch_ref is None:
raise ValueError(
"if init is None, memory at least need shape and batch_ref")
parent_block = self._parent_block()
var_name = unique_name.generate("@".join(
[self.helper.name, "memory_boot"]))
boot_var = parent_block.create_var(
name=var_name,
shape=shape,
dtype=batch_ref.dtype,
persistable=False)
parent_block.append_op(
type="fill_constant_batch_size_like",
inputs={'Input': [batch_ref]},
outputs={'Out': [boot_var]},
attrs={
'value': init_value,
'shape': boot_var.shape,
'dtype': boot_var.dtype,
'input_dim_idx': ref_batch_dim_idx,
'output_dim_idx': init_batch_dim_idx
})
return self.memory(init=boot_var)
else:
pre_mem = self.helper.create_variable(
name=unique_name.generate("@".join([self.helper.name, "mem"])),
dtype=init.dtype,
shape=init.shape)
self.memories[pre_mem.name] = StaticRNNMemoryLink(
init=init, pre_mem=pre_mem)
return pre_mem
def step_input(self, x):
self._assert_in_rnn_block_('step_input')
if not isinstance(x, Variable):
raise TypeError("step input takes a Variable")
if self.seq_len is None:
self.seq_len = x.shape[0]
elif self.seq_len != x.shape[0]:
raise ValueError("Static RNN only take fix seq_len input")
ipt = self.helper.create_variable(
name=x.name, dtype=x.dtype, shape=list(x.shape[1:]), type=x.type)
self.inputs.append(ipt)
return ipt
def step_output(self, o):
self._assert_in_rnn_block_('step_output')
if not isinstance(o, Variable):
raise TypeError("step output takes a Variable")
tmp_o = self.helper.create_tmp_variable(dtype=o.dtype)
self.helper.append_op(
type='rnn_memory_helper',
inputs={'X': [o]},
outputs={'Out': tmp_o},
attrs={'dtype': o.dtype})
out_var = self._parent_block().create_var(
name=tmp_o.name,
shape=[self.seq_len] + list(tmp_o.shape),
dtype=tmp_o.dtype)
self.outputs.append(out_var)
def output(self, *outputs):
for each in outputs:
self.step_output(each)
def update_memory(self, mem, var):
if not isinstance(mem, Variable) or not isinstance(var, Variable):
raise TypeError("update memory should take variables")
self.memories[mem.name].mem = var
def _parent_block(self):
prog = self.helper.main_program
parent_idx = prog.current_block().parent_idx
assert parent_idx >= 0
parent_block = prog.block(parent_idx)
return parent_block
def __call__(self, *args, **kwargs):
if self.status != StaticRNN.AFTER_RNN_BLOCK:
raise ValueError("RNN output can only be retrieved after rnn block")
if len(self.outputs) == 0:
raise ValueError("RNN has no output")
elif len(self.outputs) == 1:
return self.outputs[0]
else:
return self.outputs
def _complete_op(self):
main_program = self.helper.main_program
rnn_block = main_program.current_block()
parent_block = self._parent_block()
local_inputs = set()
for op in rnn_block.ops:
assert isinstance(op, Operator)
for oname in op.output_names:
for out_var_name in op.output(oname):
local_inputs.add(out_var_name)
for var in self.inputs:
local_inputs.add(var.name)
for m in self.memories:
local_inputs.add(m)
params = list()
for op in rnn_block.ops:
assert isinstance(op, Operator)
for iname in op.input_names:
for in_var_name in op.input(iname):
if in_var_name not in local_inputs:
params.append(in_var_name)
parameters = [parent_block.var(name) for name in params]
step_scope = parent_block.create_var(
type=core.VarDesc.VarType.STEP_SCOPES)
inlinks = [parent_block.var(i.name) for i in self.inputs]
outlinks = self.outputs
boot_memories = []
pre_memories = []
memories = []
for _, mem in list(self.memories.items()):
boot_memories.append(mem.init)
pre_memories.append(mem.pre_mem.name)
mem_var = rnn_block.var(mem.mem.name)
assert isinstance(mem_var, Variable)
new_mem = self.helper.create_tmp_variable(dtype=mem_var.dtype)
rnn_block.append_op(
type='rnn_memory_helper',
inputs={'X': [mem_var]},
outputs={'Out': [new_mem]},
attrs={'dtype': mem_var.dtype})
memories.append(new_mem.name)
parent_block.append_op(
type='recurrent',
inputs={
'inputs': inlinks,
'initial_states': boot_memories,
'parameters': parameters
},
outputs={'outputs': outlinks,
'step_scopes': [step_scope]},
attrs={
'ex_states': pre_memories,
'states': memories,
'sub_block': rnn_block
})
class WhileGuard(BlockGuard):
def __init__(self, while_op):
if not isinstance(while_op, While):
raise TypeError("WhileGuard takes a while op")
super(WhileGuard, self).__init__(while_op.helper.main_program)
self.while_op = while_op
def __enter__(self):
self.while_op.status = While.IN_WHILE_BLOCK
return super(WhileGuard, self).__enter__()
def __exit__(self, exc_type, exc_val, exc_tb):
if exc_type is not None:
return False
self.while_op.status = While.AFTER_WHILE_BLOCK
self.while_op._complete()
return super(WhileGuard, self).__exit__(exc_type, exc_val, exc_tb)
class While(object):
"""
while loop control flow.
Args:
cond (Variable): condition used to compare.
name (str): The name of this layer.
Examples:
.. code-block:: python
d0 = layers.data("d0", shape=[10], dtype='float32')
data_array = layers.array_write(x=d0, i=i)
array_len = layers.fill_constant(shape=[1],dtype='int64', value=3)
cond = layers.less_than(x=i, y=array_len)
while_op = layers.While(cond=cond)
with while_op.block():
d = layers.array_read(array=data_array, i=i)
i = layers.increment(x=i, in_place=True)
layers.array_write(result, i=i, array=d)
layers.less_than(x=i, y=array_len, cond=cond)
"""
BEFORE_WHILE_BLOCK = 0
IN_WHILE_BLOCK = 1
AFTER_WHILE_BLOCK = 2
def __init__(self, cond, name=None):
self.helper = LayerHelper("while", name=name)
self.status = While.BEFORE_WHILE_BLOCK
if not isinstance(cond, Variable):
raise TypeError("condition should be a variable")
assert isinstance(cond, Variable)
if cond.dtype != core.VarDesc.VarType.BOOL:
raise TypeError("condition should be a bool variable")
if reduce(lambda a, b: a * b, cond.shape, 1) != 1:
raise TypeError("condition should be a bool scalar")
self.cond_var = cond
def block(self):
return WhileGuard(self)
def _complete(self):
main_program = self.helper.main_program
while_block = main_program.current_block()
parent_block = main_program.block(main_program.current_block()
.parent_idx)
inner_outputs = {self.cond_var.name}
x_name_list = set()
for op in while_block.ops:
for iname in op.input_names:
for in_var_name in op.input(iname):
if in_var_name not in inner_outputs:
x_name_list.add(in_var_name)
for oname in op.output_names:
for out_var_name in op.output(oname):
inner_outputs.add(out_var_name)
out_vars = []
for inner_out_name in inner_outputs:
if inner_out_name in parent_block.vars:
out_vars.append(parent_block.var(inner_out_name))
step_scope = parent_block.create_var(
type=core.VarDesc.VarType.STEP_SCOPES)
parent_block.append_op(
type='while',
inputs={
'X': [
parent_block._var_recursive(x_name)
for x_name in x_name_list
],
'Condition': [self.cond_var]
},
outputs={'Out': out_vars,
'StepScopes': [step_scope]},
attrs={'sub_block': while_block})
def lod_rank_table(x, level=0):
"""LoD Rank Table Operator. Given an input variable **x** and a level number
of LoD, this layer creates a LodRankTable object. A LoDRankTable object
contains a list of bi-element tuples. Each tuple consists of an index and
a length, both of which are int type. Refering to specified level of LoD,
the index is the sequence index number and the length representes the
sequence length. Please note that the list is ranked in descending order by
the length. The following is an example:
.. code-block:: text
x is a LoDTensor:
x.lod = [[2, 1],
[5, 1, 1]]
x.data = [a, b, c, d, e, f, g]
1. set level to 0:
Create lod rank table:
lod_rank_table_obj = lod_rank_table(x, level=0)
Get:
lod_rank_table_obj.items() = [(0, 2), (1, 1)]
2. set level to 1:
Create lod rank table:
lod_rank_table_obj = lod_rank_table(x, level=1)
Get:
lod_rank_table_obj.items() = [(0, 5), (1, 1), (2, 1)]
Args:
x (Variable): Input variable, a LoDTensor based which to create the lod
rank table.
level (int): Specify the LoD level, on which to create the lod rank
table.
Returns:
Variable: The created LoDRankTable object.
Examples:
.. code-block:: python
x = fluid.layers.data(name='x', shape=[10],
dtype='float32', lod_level=1)
out = layers.lod_rank_table(x=x, level=0)
"""
helper = LayerHelper("lod_rank_table", **locals())
table = helper.create_variable(
type=core.VarDesc.VarType.LOD_RANK_TABLE,
name=unique_name.generate("lod_rank_table"))
helper.append_op(
type='lod_rank_table',
inputs={'X': x},
outputs={'Out': table},
attrs={'level': level})
return table
@templatedoc()
def max_sequence_len(rank_table):
"""
${comment}
>>> import paddle.fluid as fluid
>>> x = fluid.layers.data(name='x', shape=[10], dtype='float32',
>>> lod_level=1)
>>> rank_table = layers.lod_rank_table(x=x, level=0)
>>> max_seq_len = layers.max_sequence_len(rank_table)
Args:
rank_table(${rank_table_type}): ${rank_table_comment}.
Returns:
${out_comment}.
"""
helper = LayerHelper("max_seqence_len", **locals())
res = helper.create_tmp_variable(dtype="int64")
helper.append_op(
type="max_sequence_len",
inputs={"RankTable": rank_table},
outputs={"Out": res})
return res
def lod_tensor_to_array(x, table):
"""
Convert a LoDTensor to a LoDTensorArray.
This function split a LoDTesnor to a LoDTensorArray according to its LoD
information. LoDTensorArray is an alias of C++ std::vector<LoDTensor> in
PaddlePaddle. The generated LoDTensorArray of this function can be further read
or written by `read_from_array()` and `write_to_array()` operators. However,
this function is generally an internal component of PaddlePaddle `DynamicRNN`.
Users should not use it directly.
Args:
x (Variable|list): The LoDTensor to be converted to a LoDTensorArray.
table (ParamAttr|list): The variable that stores the level of lod
which is ordered by sequence length in
descending order. It is generally generated
by `layers.lod_rank_table()` API.
Returns:
Variable: The LoDTensorArray that has been converted from the input tensor.
Examples:
.. code-block:: python
x = fluid.layers.data(name='x', shape=[10])
table = fluid.layers.lod_rank_table(x, level=0)
array = fluid.layers.lod_tensor_to_array(x, table)
"""
helper = LayerHelper("lod_tensor_to_array", **locals())
array = helper.create_variable(
name=unique_name.generate("lod_tensor_to_array"),
type=core.VarDesc.VarType.LOD_TENSOR_ARRAY,
dtype=x.dtype)
helper.append_op(
type='lod_tensor_to_array',
inputs={'X': x,
'RankTable': table},
outputs={'Out': array})
return array
def array_to_lod_tensor(x, table):
"""Convert a LoD_Tensor_Aarry to an LoDTensor.
Args:
x (Variable|list): The lod tensor array to be converted to a tensor.
table (ParamAttr|list): The variable that stores the level of lod
which is ordered by sequence length in
descending order.
Returns:
Variable: The variable of type tensor that has been converted
from an array.
Examples:
.. code-block:: python
x = fluid.layers.data(name='x', shape=[10])
table = fluid.layers.lod_rank_table(x, level=0)
array = fluid.layers.lod_tensor_to_array(x, table)
lod_tensor = fluid.layers.array_to_lod_tensor(array, table)
"""
helper = LayerHelper("array_to_lod_tensor", **locals())
tmp = helper.create_tmp_variable(dtype=x.dtype)
helper.append_op(
type="array_to_lod_tensor",
inputs={'X': x,
'RankTable': table},
outputs={'Out': tmp})
return tmp
def increment(x, value=1.0, in_place=True):
"""
This function performs an operation that increments each value in the
input :math:`x` by an amount: :math:`value` as mentioned in the input
parameter. This operation is performed in-place by default.
Args:
x (Variable|list): The tensor that has the input values.
value (float): The amount by which the values should be incremented.
in_place (bool): If the increment should be performed in-place.
Returns:
Variable: The elementwise-incremented object.
Examples:
.. code-block:: python
data = fluid.layers.data(name='data', shape=[32, 32], dtype='float32')
data = fluid.layers.increment(x=data, value=3.0, in_place=True)
"""
helper = LayerHelper("increment", **locals())
if not in_place:
out = helper.create_tmp_variable(dtype=x.dtype)
else:
out = x
helper.append_op(
type='increment',
inputs={'X': [x]},
outputs={'Out': [out]},
attrs={'step': float(value)})
return out
def array_write(x, i, array=None):
"""
This function writes the given input variable to the specified position
indicating by the arrary index to an output LOD_TENSOR_ARRAY. If the
output LOD_TENSOR_ARRAY is not given(None), a new one will be created and
returned.
Args:
x (Variable|list): The input tensor from which the data will be read.
i (Variable|list): The index of the output LOD_TENSOR_ARRAY, pointing to
the position to which the input tensor will be
written.
array (Variable|list): The output LOD_TENSOR_ARRAY to which the input
tensor will be written. If this parameter is
NONE, a new LOD_TENSOR_ARRAY will be created and
returned.
Returns:
Variable: The output LOD_TENSOR_ARRAY where the input tensor is written.
Examples:
.. code-block:: python
tmp = fluid.layers.zeros(shape=[10], dtype='int32')
i = fluid.layers.fill_constant(shape=[1], dtype='int64', value=10)
arr = layers.array_write(tmp, i=i)
"""
helper = LayerHelper('array_write', **locals())
if array is None:
array = helper.create_variable(
name="{0}.out".format(helper.name),
type=core.VarDesc.VarType.LOD_TENSOR_ARRAY,
dtype=x.dtype)
helper.append_op(
type='write_to_array',
inputs={'X': [x],
'I': [i]},
outputs={'Out': [array]})
return array
def create_array(dtype):
"""
**Create LoDTensorArray**
This function creates an array of LOD_TENSOR_ARRAY . It is mainly used to
implement RNN with array_write, array_read and While.
Args:
dtype (int|float): The data type of the elements in the lod_tensor_array.
Returns:
Variable: The lod_tensor_array variable storing the elements of data type.
Examples:
.. code-block:: python
data = fluid.layers.create_array(dtype='float32')
"""
helper = LayerHelper("array", **locals())
return helper.create_variable(
name="{0}.out".format(helper.name),
type=core.VarDesc.VarType.LOD_TENSOR_ARRAY,
dtype=dtype)
@templatedoc()
def less_than(x, y, force_cpu=None, cond=None, **ignored):
"""
${comment}
>>> import paddle.fluid as fluid
>>> less = fluid.layers.less_than(x=label, y=limit)
Args:
x(${x_type}): ${x_comment}.
y(${y_type}): ${y_comment}.
force_cpu(${force_cpu_type}): ${force_cpu_comment}.
cond(Variable|None): Optional output variable to store the result of *less_than*
Returns:
${out_comment}.
"""
helper = LayerHelper("less_than", **locals())
if cond is None:
cond = helper.create_tmp_variable(dtype='bool')
cond.stop_gradient = True
attrs = dict()
if force_cpu is not None:
attrs['force_cpu'] = force_cpu
elif force_init_on_cpu():
attrs['force_cpu'] = force_init_on_cpu()
helper.append_op(
type='less_than',
inputs={'X': [x],
'Y': [y]},
outputs={'Out': [cond]},
attrs=attrs)
return cond
def equal(x, y, cond=None, **ignored):
"""
**equal**
This layer returns the truth value of :math:`x == y` elementwise.
Args:
x(Variable): First operand of *equal*
y(Variable): Second operand of *equal*
cond(Variable|None): Optional output variable to store the result of *equal*
Returns:
Variable: The tensor variable storing the output of *equal*.
Examples:
.. code-block:: python
less = fluid.layers.equal(x=label, y=limit)
"""
helper = LayerHelper("equal", **locals())
if cond is None:
cond = helper.create_tmp_variable(dtype='bool')
cond.stop_gradient = True
helper.append_op(
type='equal', inputs={'X': [x],
'Y': [y]}, outputs={'Out': [cond]})
return cond
def array_read(array, i):
"""
This function performs the operation to read the data in as an
LOD_TENSOR_ARRAY.
.. code-block:: text
Given:
array = [0.6, 0.1, 0.3, 0.1]
And:
i = 2
Then:
output = 0.3
Args:
array (Variable|list): The input tensor that store data to be read.
i (Variable|list): The index of the data to be read from input array.
Returns:
Variable: The tensor type variable that has the data written to it.
Examples:
.. code-block:: python
tmp = fluid.layers.zeros(shape=[10], dtype='int32')
i = fluid.layers.fill_constant(shape=[1], dtype='int64', value=10)
arr = layers.array_read(tmp, i=i)
"""
helper = LayerHelper('array_read', **locals())
if not isinstance(
array,
Variable) or array.type != core.VarDesc.VarType.LOD_TENSOR_ARRAY:
raise TypeError("array should be tensor array vairable")
out = helper.create_tmp_variable(dtype=array.dtype)
helper.append_op(
type='read_from_array',
inputs={'X': [array],
'I': [i]},
outputs={'Out': [out]})
return out
def shrink_memory(x, i, table):
"""
This function creates an operator to shrink rnn memory using the RankTable
as mentioned in the input parameter.
NOTE: This API is very low-level API. It is used by DynamicRNN only.
Since the Dynamic RNN uses no-padding way to implement RNN. The sequence
will be sorted by order, and the length of valid memory will be shrink after
each time step.
Args:
x(Variable): The memory object in the previous time step.
i(Variable): The step count variable. A int scalar as LoDTensor.
table(Variable): The RNNRankTable object.
Returns:
the memory variable after shrink.
Examples:
Since this API is very low level API. The example is not provided.
Please reference the implementation of class DynamicRNN for detail
usage.
"""
helper = LayerHelper('shrink_memory', **locals())
out = helper.create_tmp_variable(dtype=x.dtype)
helper.append_op(
type='shrink_rnn_memory',
inputs={'X': [x],
'I': [i],
'RankTable': [table]},
outputs={'Out': [out]},
attrs={})
return out
def array_length(array):
"""
**Get the Length of Input LoDTensorArray**
This function performs the operation to find the length of the input
LOD_TENSOR_ARRAY.
Related API: array_read, array_write, While.
Args:
array (LOD_TENSOR_ARRAY): The input array that will be used
to compute the length.
Returns:
Variable: The length of the input LoDTensorArray.
Examples:
.. code-block:: python
tmp = fluid.layers.zeros(shape=[10], dtype='int32')
i = fluid.layers.fill_constant(shape=[1], dtype='int64', value=10)
arr = fluid.layers.array_write(tmp, i=i)
arr_len = fluid.layers.array_length(arr)
"""
helper = LayerHelper('array_length', **locals())
tmp = helper.create_tmp_variable(dtype='int64')
tmp.stop_gradient = True
helper.append_op(
type='lod_array_length', inputs={'X': [array]}, outputs={'Out': [tmp]})
return tmp
class ConditionalBlockGuard(BlockGuard):
"""
ConditionalBlockGuard is derived from BlockGuard. It is dedicated for
holding a ConditionalBlock, and helping users entering and exiting the
ConditionalBlock via Python's 'with' keyword. However, ConditionalBlockGuard
is generally an internal component of IfElse, users should not use it directly.
"""
def __init__(self, block):
if not isinstance(block, ConditionalBlock):
raise TypeError("block should be conditional block")
super(ConditionalBlockGuard, self).__init__(block.helper.main_program)
self.block = block
def __enter__(self):
return super(ConditionalBlockGuard, self).__enter__()
def __exit__(self, exc_type, exc_val, exc_tb):
self.block.complete()
return super(ConditionalBlockGuard, self).__exit__(exc_type, exc_val,
exc_tb)
class ConditionalBlock(object):
'''
**ConditionalBlock**
ConditionalBlock is an operator that bind a block to a specific condition,
if the condition matches, the corresponding block will be executed.
Args:
inputs (Variable): bool conditions.
is_scalar_condition (bool): whether the branch is controled by a scalar.
name(str): name of this ConditionalBlock.
Examples:
.. code-block:: python
cond = layers.less_than(x=label, y=limit)
true_image, false_image = layers.split_lod_tensor(
input=image, mask=cond)
true_cond = layers.ConditionalBlock([true_image])
with true_cond.block():
...
with false_cond.block():
...
'''
def __init__(self, inputs, is_scalar_condition=False, name=None):
for each_input in inputs:
if not isinstance(each_input, Variable):
raise TypeError("Each input should be variable")
self.inputs = inputs
self.is_scalar_condition = is_scalar_condition
self.helper = LayerHelper('conditional_block', name=name)
def block(self):
return ConditionalBlockGuard(self)
def complete(self):
inside_block = self.helper.main_program.current_block()
parent_block = self.helper.main_program.block(inside_block.parent_idx)
intermediate = set()
params = set()
for each_op in inside_block.ops:
assert isinstance(each_op, Operator)
for iname in each_op.input_names:
for in_var_name in each_op.input(iname):
if in_var_name not in intermediate:
params.add(in_var_name)
for oname in each_op.output_names:
for out_var_name in each_op.output(oname):
intermediate.add(out_var_name)
input_set = set([ipt.name for ipt in self.inputs])
param_list = [
parent_block._var_recursive(each_name) for each_name in params
if each_name not in input_set
]
out_list = [
parent_block.var(var_name) for var_name in parent_block.vars
if var_name in intermediate
]
step_scope = parent_block.create_var(
type=core.VarDesc.VarType.STEP_SCOPES)
parent_block.append_op(
type='conditional_block',
inputs={
'X': self.inputs,
'Params': param_list,
},
outputs={'Out': out_list,
'Scope': [step_scope]},
attrs={
'sub_block': inside_block,
'is_scalar_condition': self.is_scalar_condition
})
class Switch(object):
"""
Switch class works just like a `if-elif-else`. Can be used in learning rate scheduler
to modify learning rate
The Semantics:
1. A `switch` control-flow checks cases one-by-one.
2. The condition of each case is a boolean value, which is a scalar Variable.
3. It runs the first matched case, or the default case if there is one.
4. Once it matches a case, it runs the corresponding branch and only that branch.
Examples:
.. code-block:: python
lr = fluid.layers.tensor.create_global_var(
shape=[1],
value=0.0,
dtype='float32',
persistable=True,
name="learning_rate")
one_var = tensor.fill_constant(
shape=[1], dtype='float32', value=1.0)
two_var = tensor.fill_constant(
shape=[1], dtype='float32', value=2.0)
with fluid.layers.control_flow.Switch() as switch:
with switch.case(global_step == zero_var):
fluid.layers.tensor.assign(input=one_var, output=lr)
with switch.default():
fluid.layers.tensor.assign(input=two_var, output=lr)
"""
def __init__(self, name=None):
self.helper = LayerHelper('switch', name=name)
self.inside_scope = False
self.pre_not_conditions = []
def case(self, condition):
"""create a new block for this condition
"""
if not self.inside_scope:
raise ValueError("case should be called inside with")
if len(self.pre_not_conditions) == 0:
cond_block = ConditionalBlock([condition], is_scalar_condition=True)
not_cond = logical_not(x=condition)
self.pre_not_conditions.append(not_cond)
else:
pre_cond_num = len(self.pre_not_conditions)
pre_not_cond = self.pre_not_conditions[pre_cond_num - 1]
new_not_cond = logical_and(
x=pre_not_cond, y=logical_not(x=condition))
self.pre_not_conditions.append(new_not_cond)
cond_block = ConditionalBlock(
[logical_and(
x=pre_not_cond, y=condition)],
is_scalar_condition=True)
return ConditionalBlockGuard(cond_block)
def default(self):
"""
create a default case for this switch
"""
pre_cond_num = len(self.pre_not_conditions)
if pre_cond_num == 0:
raise ValueError("there should be at least one condition")
cond_block = ConditionalBlock(
[self.pre_not_conditions[pre_cond_num - 1]],
is_scalar_condition=True)
return ConditionalBlockGuard(cond_block)
def __enter__(self):
"""
set flag that now is inside switch.block {}
:return:
"""
self.inside_scope = True
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.inside_scope = False
if exc_type is not None:
return False # re-raise exception
return True
class IfElseBlockGuard(object):
def __init__(self, is_true, ifelse):
if not isinstance(ifelse, IfElse):
raise TypeError("ifelse must be an instance of IfElse class")
if ifelse.status != IfElse.OUT_IF_ELSE_BLOCKS:
raise ValueError("You cannot invoke IfElse.block() inside a block")
self.is_true = is_true
self.ie = ifelse
if is_true:
self.cond_block = ifelse.conditional_true_block
else:
self.cond_block = ifelse.conditional_false_block
if not isinstance(self.cond_block, ConditionalBlock):
raise TypeError("Unexpected situation")
self.cond_block = self.cond_block.block()
def __enter__(self):
self.ie.status = IfElse.IN_IF_ELSE_TRUE_BLOCKS if self.is_true else IfElse.IN_IF_ELSE_FALSE_BLOCKS
self.cond_block.__enter__()
def __exit__(self, exc_type, exc_val, exc_tb):
if not self.cond_block.__exit__(exc_type, exc_val, exc_tb):
# re-raise inside exception
return False
if len(self.ie.output_table[1 if self.is_true else 0]) == 0:
raise ValueError("Must set output inside block")
self.ie.status = IfElse.OUT_IF_ELSE_BLOCKS
class IfElse(object):
"""
if-else control flow.
Args:
cond (Variable): condition used to compare.
name (str, default None): The name of this layer.
Examples:
.. code-block:: python
limit = fluid.layers.fill_constant_batch_size_like(
input=label, dtype='int64', shape=[1], value=5.0)
cond = fluid.layers.less_than(x=label, y=limit)
ie = fluid.layers.IfElse(cond)
with ie.true_block():
true_image = ie.input(image)
hidden = fluid.layers.fc(input=true_image, size=100, act='tanh')
prob = fluid.layers.fc(input=hidden, size=10, act='softmax')
ie.output(prob)
with ie.false_block():
false_image = ie.input(image)
hidden = fluid.layers.fc(
input=false_image, size=200, act='tanh')
prob = fluid.layers.fc(input=hidden, size=10, act='softmax')
ie.output(prob)
prob = ie()
"""
OUT_IF_ELSE_BLOCKS = 0
IN_IF_ELSE_TRUE_BLOCKS = 1
IN_IF_ELSE_FALSE_BLOCKS = 2
def __init__(self, cond, name=None):
if not isinstance(cond, Variable):
raise TypeError("cond must be a Variable")
self.helper = LayerHelper('ifelse', name=name)
self.cond = cond
self.input_table = {}
self.status = IfElse.OUT_IF_ELSE_BLOCKS
self.conditional_true_block = ConditionalBlock(inputs=[self.cond])
self.conditional_false_block = ConditionalBlock(inputs=[self.cond])
self.output_table = ([], []) # (true_outs, false_outs)
def input(self, x):
if self.status == IfElse.OUT_IF_ELSE_BLOCKS:
raise ValueError("input must in true/false blocks")
if id(x) not in self.input_table:
parent_block = self._parent_block()
out_true = parent_block.create_var(
name=unique_name.generate('ifelse_input' + self.helper.name),
dtype=x.dtype)
out_false = parent_block.create_var(
name=unique_name.generate('ifelse_input' + self.helper.name),
dtype=x.dtype)
parent_block.append_op(
type='split_lod_tensor',
inputs={
'X': x,
'Mask': self.cond,
},
outputs={'OutTrue': out_true,
'OutFalse': out_false},
attrs={'level': 0})
self.input_table[id(x)] = (out_true, out_false)
else:
out_true, out_false = self.input_table[id(x)]
if self.status == IfElse.IN_IF_ELSE_TRUE_BLOCKS:
return out_true
else:
return out_false
def _parent_block(self):
current_block = self.helper.main_program.current_block()
return self.helper.main_program.block(current_block.parent_idx)
def true_block(self):
return IfElseBlockGuard(True, self)
def false_block(self):
return IfElseBlockGuard(False, self)
def output(self, *outs):
if self.status == self.OUT_IF_ELSE_BLOCKS:
raise ValueError("output can only be invoked in the sub-block")
out_table = self.output_table[1 if self.status ==
self.IN_IF_ELSE_TRUE_BLOCKS else 0]
parent_block = self._parent_block()
for each_out in outs:
if not isinstance(each_out, Variable):
raise TypeError("Each output should be a variable")
# create outside tensor
outside_out = parent_block.create_var(
name=unique_name.generate("_".join(
[self.helper.name, 'output'])),
dtype=each_out.dtype)
out_table.append(outside_out)
# assign local var to outside
assign(input=each_out, output=outside_out)
def __call__(self):
if self.status != self.OUT_IF_ELSE_BLOCKS:
raise ValueError("IfElse::__call__ must be out of sub-block")
false_len, true_len = list(map(len, self.output_table))
if false_len == 0 and true_len == 0:
raise ValueError("Must invoke true_block/false_block before "
"__call__")
elif false_len != true_len and false_len != 0 and true_len != 0:
raise ValueError("The output side must be same")
elif false_len == 0 or true_len == 0:
return self.output_table[0 if false_len != 0 else 1]
# else none of false_len/true_len is zero
# merge together
rlist = []
for false_var, true_var in zip(*self.output_table):
rlist.append(
merge_lod_tensor(
in_true=true_var,
in_false=false_var,
mask=self.cond,
x=self.cond,
level=0))
return rlist
class DynamicRNN(object):
"""
The dynamic RNN can process a batch of sequence data. The length of each
sample sequence can be different. This API automatically process them in
batch.
The input lod must be set. Please reference `lod_tensor`
>>> import paddle.fluid as fluid
>>> data = fluid.layers.data(name='sentence', dtype='int64', lod_level=1)
>>> embedding = fluid.layers.embedding(input=data, size=[65535, 32],
>>> is_sparse=True)
>>>
>>> drnn = fluid.layers.DynamicRNN()
>>> with drnn.block():
>>> word = drnn.step_input(embedding)
>>> prev = drnn.memory(shape=[200])
>>> hidden = fluid.layers.fc(input=[word, prev], size=200, act='relu')
>>> drnn.update_memory(prev, hidden) # set prev to hidden
>>> drnn.output(hidden)
>>>
>>> # last is the last time step of rnn. It is the encoding result.
>>> last = fluid.layers.sequence_last_step(drnn())
The dynamic RNN will unfold sequence into timesteps. Users need to define
how to process each time step during the :code:`with` block.
The `memory` is used staging data cross time step. The initial value of
memory can be zero or another variable.
The dynamic RNN can mark multiple variables as its output. Use `drnn()` to
get the output sequence.
"""
BEFORE_RNN = 0
IN_RNN = 1
AFTER_RNN = 2
def __init__(self, name=None):
self.helper = LayerHelper('dynamic_rnn', name=name)
self.status = DynamicRNN.BEFORE_RNN
self.lod_rank_table = None
self.max_seq_len = None
self.step_idx = None
self.zero_idx = fill_constant(
shape=[1], value=0, dtype='int64', force_cpu=True)
self.mem_dict = dict()
self.output_array = []
self.outputs = []
self.cond = self.helper.create_tmp_variable(dtype='bool')
self.cond.stop_gradient = False
self.while_op = While(self.cond)
self.input_array = []
self.mem_link = []
def step_input(self, x):
"""
Mark a sequence as a dynamic RNN input.
Args:
x(Variable): The input sequence.
Returns:
The current timestep in the input sequence.
"""
self._assert_in_rnn_block_("step_input")
if not isinstance(x, Variable):
raise TypeError(
"step_input() can only take a Variable as its input.")
parent_block = self._parent_block_()
if self.lod_rank_table is None:
self.lod_rank_table = parent_block.create_var(
name=unique_name.generate('lod_rank_table'),
type=core.VarDesc.VarType.LOD_RANK_TABLE)
self.lod_rank_table.stop_gradient = True
parent_block.append_op(
type='lod_rank_table',
inputs={"X": x},
outputs={"Out": self.lod_rank_table})
self.max_seq_len = parent_block.create_var(
name=unique_name.generate('dynamic_rnn_max_seq_len'),
dtype='int64')
self.max_seq_len.stop_gradient = False
parent_block.append_op(
type='max_sequence_len',
inputs={'RankTable': self.lod_rank_table},
outputs={"Out": self.max_seq_len})
self.cond.stop_gradient = True
parent_block.append_op(
type='less_than',
inputs={'X': self.step_idx,
'Y': self.max_seq_len},
outputs={'Out': self.cond},
attrs={'force_cpu': True})
input_array = parent_block.create_var(
name=unique_name.generate('dynamic_rnn_input_array'),
type=core.VarDesc.VarType.LOD_TENSOR_ARRAY,
dtype=x.dtype)
self.input_array.append((input_array, x.dtype))
parent_block.append_op(
type='lod_tensor_to_array',
inputs={'X': x,
'RankTable': self.lod_rank_table},
outputs={'Out': input_array})
return array_read(array=input_array, i=self.step_idx)
def static_input(self, x):
"""
Mark a variable as a RNN input. The input will not be scattered into
time steps.
Args:
x(Variable): The input variable.
Returns:
The input variable that can access in RNN.
"""
self._assert_in_rnn_block_("static_input")
if not isinstance(x, Variable):
raise TypeError(
"static_input() can only take a Variable as its input")
if self.lod_rank_table is None:
raise RuntimeError(
"static_input() must be called after step_input().")
parent_block = self._parent_block_()
x_reordered = parent_block.create_var(
name=unique_name.generate("dynamic_rnn_static_input_reordered"),
type=core.VarDesc.VarType.LOD_TENSOR,
dtype=x.dtype)
parent_block.append_op(
type='reorder_lod_tensor_by_rank',
inputs={'X': [x],
'RankTable': [self.lod_rank_table]},
outputs={'Out': [x_reordered]})
return shrink_memory(x_reordered, self.step_idx, self.lod_rank_table)
@contextlib.contextmanager
def block(self):
"""
The block for user to define operators in RNN. See the class docstring
for more details.
"""
if self.status != DynamicRNN.BEFORE_RNN:
raise ValueError("rnn.block() can only be invoke once")
self.step_idx = fill_constant(
shape=[1], dtype='int64', value=0, force_cpu=True)
self.step_idx.stop_gradient = False
self.status = DynamicRNN.IN_RNN
with self.while_op.block():
yield
increment(x=self.step_idx, value=1.0, in_place=True)
for new_mem, mem_array in self.mem_link:
array_write(x=new_mem, i=self.step_idx, array=mem_array)
less_than(
x=self.step_idx,
y=self.max_seq_len,
force_cpu=True,
cond=self.cond)
self.status = DynamicRNN.AFTER_RNN
for each_array in self.output_array:
self.outputs.append(
array_to_lod_tensor(
x=each_array, table=self.lod_rank_table))
def __call__(self, *args, **kwargs):
"""
Get the output of RNN. This API should only be invoked after RNN.block()
"""
if self.status != DynamicRNN.AFTER_RNN:
raise ValueError(("Output of the dynamic RNN can only be visited "
"outside the rnn block."))
if len(self.outputs) == 1:
return self.outputs[0]
else:
return self.outputs
def memory(self,
init=None,
shape=None,
value=0.0,
need_reorder=False,
dtype='float32'):
"""
Create a memory variable for dynamic rnn.
If the :code:`init` is not None, :code:`memory` will be initialized by
this variable. The :code:`need_reorder` is used to reorder the memory as
the input variable. It should be set to true when the initialized memory
depends on the input sample.
For example,
>>> import paddle.fluid as fluid
>>> sentence = fluid.layers.data(
>>> name='sentence', dtype='float32', shape=[32])
>>> boot_memory = fluid.layers.data(
>>> name='boot', dtype='float32', shape=[10])
>>>
>>> drnn = fluid.layers.DynamicRNN()
>>> with drnn.block():
>>> word = drnn.step_input(sentence)
>>> memory = drnn.memory(init=boot_memory, need_reorder=True)
>>> hidden = fluid.layers.fc(
>>> input=[word, memory], size=10, act='tanh')
>>> drnn.update_memory(ex_mem=memory, new_mem=hidden)
>>> drnn.output(hidden)
>>> rnn_output = drnn()
Otherwise, if :code:`shape`, :code:`value`, :code:`dtype` are set, the
:code:`memory` will be initialized by this :code:`value`.
For example,
>>> import paddle.fluid as fluid
>>> sentence = fluid.layers.data(
>>> name='sentence', dtype='float32', shape=[32])
>>>
>>> drnn = fluid.layers.DynamicRNN()
>>> with drnn.block():
>>> word = drnn.step_input(sentence)
>>> memory = drnn.memory(shape=[10], dtype='float32', value=0)
>>> hidden = fluid.layers.fc(
>>> input=[word, memory], size=10, act='tanh')
>>> drnn.update_memory(ex_mem=memory, new_mem=hidden)
>>> drnn.output(hidden)
>>> rnn_output = drnn()
Args:
init(Variable|None): The initialized variable.
shape(list|tuple): The memory shape. NOTE the shape does not contain
batch_size.
value(float): the initalized value.
need_reorder(bool): True if the initialized memory depends on the
input sample.
dtype(str|numpy.dtype): The data type of the initialized memory.
Returns:
the memory variable.
"""
self._assert_in_rnn_block_('memory')
if init is not None:
if not isinstance(init, Variable):
raise TypeError(
"The input arg `init` of memory() must be a Variable")
parent_block = self._parent_block_()
init_tensor = init
if need_reorder == True:
if self.lod_rank_table is None:
raise ValueError(
'If set need_reorder to True, make sure step_input be '
'invoked before '
'memory(init=init, need_reordered=True, ...).')
init_reordered = parent_block.create_var(
name=unique_name.generate('dynamic_rnn_mem_init_reordered'),
type=core.VarDesc.VarType.LOD_TENSOR,
dtype=init.dtype)
parent_block.append_op(
type='reorder_lod_tensor_by_rank',
inputs={
'X': [init_tensor],
'RankTable': [self.lod_rank_table]
},
outputs={'Out': [init_reordered]})
init_tensor = init_reordered
mem_array = parent_block.create_var(
name=unique_name.generate('dynamic_rnn_mem_array'),
type=core.VarDesc.VarType.LOD_TENSOR_ARRAY,
dtype=init.dtype)
parent_block.append_op(
type='write_to_array',
inputs={'X': init_tensor,
'I': self.zero_idx},
outputs={'Out': mem_array})
retv = array_read(array=mem_array, i=self.step_idx)
retv = shrink_memory(
x=retv, i=self.step_idx, table=self.lod_rank_table)
self.mem_dict[retv.name] = mem_array
return retv
else:
if len(self.input_array) == 0:
raise ValueError(
"step_input should be invoked before memory(shape=..., value=...)"
)
parent_block = self._parent_block_()
init = parent_block.create_var(
name=unique_name.generate('mem_init'), dtype=dtype)
arr, dtype = self.input_array[0]
in0 = parent_block.create_var(
name=unique_name.generate('in0'), dtype=dtype)
parent_block.append_op(
type='read_from_array',
inputs={'X': [arr],
'I': [self.zero_idx]},
outputs={'Out': [in0]})
parent_block.append_op(
type='fill_constant_batch_size_like',
inputs={'Input': [in0]},
outputs={'Out': [init]},
attrs={
'shape': [-1] + shape,
'value': float(value),
'dtype': init.dtype
})
return self.memory(init=init)
def update_memory(self, ex_mem, new_mem):
"""
Update the memory from ex_mem to new_mem. NOTE that the shape and data
type of :code:`ex_mem` and :code:`new_mem` must be same.
Args:
ex_mem(Variable): the memory variable.
new_mem(Variable): the plain variable generated in RNN block.
Returns:
None
"""
self._assert_in_rnn_block_('update_memory')
if not isinstance(ex_mem, Variable):
raise TypeError("The input arg `ex_mem` of update_memory() must "
"be a Variable")
if not isinstance(new_mem, Variable):
raise TypeError("The input arg `new_mem` of update_memory() must "
"be a Variable")
mem_array = self.mem_dict.get(ex_mem.name, None)
if mem_array is None:
raise ValueError("Please invoke memory before update_memory")
if self.lod_rank_table is None:
raise ValueError("Please invoke step_input before update_memory")
self.mem_link.append((new_mem, mem_array))
def output(self, *outputs):
"""
mark the RNN output variables.
Args:
outputs: The output variables.
Returns:
None
"""
self._assert_in_rnn_block_('output')
parent_block = self._parent_block_()
for each in outputs:
outside_array = parent_block.create_var(
name=unique_name.generate("_".join(
[self.helper.name, "output_array", each.name])),
type=core.VarDesc.VarType.LOD_TENSOR_ARRAY,
dtype=each.dtype)
array_write(x=each, i=self.step_idx, array=outside_array)
self.output_array.append(outside_array)
def _parent_block_(self):
prog = self.helper.main_program
parent_idx = prog.current_block().parent_idx
assert parent_idx >= 0
parent_block = prog.block(parent_idx)
return parent_block
def _assert_in_rnn_block_(self, method):
if self.status != DynamicRNN.IN_RNN:
raise ValueError("{0} can only be invoked inside rnn block.".format(
method))
@autodoc()
def reorder_lod_tensor_by_rank(x, rank_table):
helper = LayerHelper('reorder_lod_tensor_by_rank', **locals())
helper.is_instance('x', Variable)
helper.is_instance('rank_table', Variable)
out = helper.create_tmp_variable(dtype=x.dtype)
helper.append_op(
type='reorder_lod_tensor_by_rank',
inputs={'X': [x],
'RankTable': [rank_table]},
outputs={'Out': [out]})
return out
def is_empty(x, cond=None, **ignored):
"""
Test whether a Variable is empty.
Args:
x (Variable): The Variable to be tested.
cond (Variable|None): Output parameter. Returns the test result
of given 'x'. Default: None
Returns:
Variable: A bool scalar. True if 'x' is an empty Variable.
Raises:
TypeError: If input cond is not a variable, or cond's dtype is
not bool.
Examples:
.. code-block:: python
res = fluid.layers.is_empty(x=input)
# or:
fluid.layers.is_empty(x=input, cond=res)
"""
helper = LayerHelper("is_empty", **locals())
if cond is None:
cond = helper.create_tmp_variable(dtype='bool')
cond.stop_gradient = True
elif not isinstance(cond, Variable):
raise TypeError("cond takes a variable")
elif cond.dtype != 'bool':
raise TypeError("The data type of cond must be bool")
helper.append_op(
type='is_empty', inputs={'X': [x]}, outputs={'Out': [cond]})
return cond
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