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Paddle/python/paddle/nn/functional/activation.py

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6.4 KiB

# Copyright (c) 2020 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 warnings
from ...fluid.layer_helper import LayerHelper
from ...fluid.framework import in_dygraph_mode, convert_np_dtype_to_dtype_
from ...fluid import core
# TODO: define activation functions of neural network
__all__ = [
# 'brelu',
# 'elu',
# 'erf',
# 'gelu',
# 'hard_shrink',
# 'hard_sigmoid',
# 'hard_swish',
# 'hsigmoid',
# 'leaky_relu',
# 'logsigmoid',
# 'maxout',
# 'prelu',
'relu',
# 'relu6',
# 'selu',
# 'sigmoid',
# 'soft_relu',
# 'softmax',
# 'softplus',
# 'softshrink',
# 'softsign',
# 'swish',
# 'tanh_shrink',
# 'thresholded_relu',
'log_softmax',
]
def relu(input, inplace=False, name=None):
"""
ReLU Activation.
.. math:
out = max(x, 0)
Parameters:
input (Variable): The input variable. A multi-dimension Tensor with type float16, float32, or float64.
inplace (bool, optional): If inplace is True, the input and output of ``ReLU`` are the same variable.
Otherwise, the input and output of ``ReLU`` are different variables. Default: False. Note that if x is
more than one OPs' input, inplace must be False.
name (str, optional): The default value is None. Normally there is no need for user to set this property.
For more information, please refer to :ref:`api_guide_Name` .
Returns:
Output of relu operator, a Tensor with shape same as input
Examples:
.. code-block:: python
import paddle.fluid as fluid
import paddle.nn.functional as functional
import numpy as np
data = np.array([-2, 0, 1]).astype('float32')
with fluid.dygraph.guard():
data = fluid.dygraph.to_variable(data)
res = functional.relu(data) # [0, 0, 1]
"""
if in_dygraph_mode():
if inplace:
warnings.warn(
"Inplace on ReLU is not allowed and will be discarded in dygraph mode currently."
)
return core.ops.relu(input)
helper = LayerHelper('relu', **locals())
outs = input if inplace else helper.create_variable_for_type_inference(
input.dtype)
helper.append_op(type='relu', inputs={'X': [input]}, outputs={'Out': outs})
return outs
def log_softmax(input, axis=None, dtype=None, name=None):
"""
This operator implements the log_softmax layer. The calculation process is as follows:
.. math::
Out[i, j] = log(softmax(x))
= log(\\frac{\exp(X[i, j])}{\sum_j(exp(X[i, j])})
Parameters:
input (Variable): The input variable. A multi-dimension Tensor with type float32, or float64.
axis (int, optional): The index of dimension to perform softmax calculations, it should be in
range :math:`[-1, rank-1]`, while :math:`rank` is the rank of input variable. Default: None.
None and -1 means the last dimension.
dtype (np.dtype|core.VarDesc.VarType|str): The desired data type of returned tensor. If specified,
the input tensor is casted to dtype before the operation is performed. This is useful for
preventing data type overflows. Default: None. Supported dtype: float32 or float64
name (str, optional): The default value is None. Normally there is no need for user to set this property.
For more information, please refer to :ref:`api_guide_Name` .
Returns:
Variable: ``Tensor`` indicates the output of softmax. The data type and shape are the same as ``input``.
Examples:
.. code-block:: python
import paddle.fluid as fluid
import paddle.nn.functional as F
import numpy as np
data = np.array([[[-2.0, 3.0, -4.0, 5.0],
[3.0, -4.0, 5.0, -6.0],
[-7.0, -8.0, 8.0, 9.0]],
[[1.0, -2.0, -3.0, 4.0],
[-5.0, 6.0, 7.0, -8.0],
[6.0, 7.0, 8.0, 9.0]]]).astype('float32')
with fluid.dygraph.guard():
data = fluid.dygraph.to_variable(data)
res = F.log_softmax(data, -1)
# [[[ -7.1278396 -2.1278396 -9.127839 -0.12783948]
# [ -2.1270514 -9.127051 -0.12705144 -11.127051 ]
# [-16.313261 -17.313261 -1.3132617 -0.31326184]]
# [[ -3.0518122 -6.051812 -7.051812 -0.051812 ]
# [-12.313267 -1.3132664 -0.3132665 -15.313267 ]
# [ -3.4401896 -2.4401896 -1.4401896 -0.44018966]]]
"""
axis = -1 if axis is None else axis
dtype = convert_np_dtype_to_dtype_(dtype) if dtype is not None else dtype
if in_dygraph_mode():
outs_cast = input if dtype is None \
else core.ops.cast(input, 'in_dtype', input.dtype, 'out_dtype', dtype)
outs_softmax = core.ops.softmax(outs_cast, 'axis', axis, 'use_cudnn',
False)
return core.ops.log(outs_softmax)
helper = LayerHelper("log_softmax", **locals())
outs_cast = input
if dtype is not None:
outs_cast = helper.create_variable_for_type_inference(dtype)
helper.append_op(
type='cast',
inputs={'X': input},
outputs={'Out': outs_cast},
attrs={'in_dtype': input.dtype,
'out_dtype': dtype})
outs_softmax = helper.create_variable_for_type_inference(outs_cast.dtype)
helper.append_op(
type='softmax',
inputs={'X': outs_cast},
outputs={'Out': outs_softmax},
attrs={'axis': axis,
'use_cudnn': False})
outs_log = helper.create_variable_for_type_inference(outs_softmax.dtype)
helper.append_op(
type='log', inputs={'X': outs_softmax}, outputs={'Out': outs_log})
return outs_log