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Paddle/python/paddle/vision/models/mobilenetv2.py

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# 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 numpy as np
import paddle
import paddle.fluid as fluid
from paddle.fluid.param_attr import ParamAttr
from paddle.fluid.dygraph.nn import Conv2D, Pool2D, BatchNorm, Linear
from paddle.utils.download import get_weights_path_from_url
__all__ = ['MobileNetV2', 'mobilenet_v2']
model_urls = {
'mobilenetv2_1.0':
('https://paddle-hapi.bj.bcebos.com/models/mobilenet_v2_x1.0.pdparams',
'8ff74f291f72533f2a7956a4efff9d88')
}
class ConvBNLayer(fluid.dygraph.Layer):
def __init__(self,
num_channels,
filter_size,
num_filters,
stride,
padding,
channels=None,
num_groups=1,
use_cudnn=True):
super(ConvBNLayer, self).__init__()
tmp_param = ParamAttr(name=self.full_name() + "_weights")
self._conv = Conv2D(
num_channels=num_channels,
num_filters=num_filters,
filter_size=filter_size,
stride=stride,
padding=padding,
groups=num_groups,
act=None,
use_cudnn=use_cudnn,
param_attr=tmp_param,
bias_attr=False)
self._batch_norm = BatchNorm(
num_filters,
param_attr=ParamAttr(name=self.full_name() + "_bn" + "_scale"),
bias_attr=ParamAttr(name=self.full_name() + "_bn" + "_offset"),
moving_mean_name=self.full_name() + "_bn" + '_mean',
moving_variance_name=self.full_name() + "_bn" + '_variance')
def forward(self, inputs, if_act=True):
y = self._conv(inputs)
y = self._batch_norm(y)
if if_act:
y = fluid.layers.relu6(y)
return y
class InvertedResidualUnit(fluid.dygraph.Layer):
def __init__(
self,
num_channels,
num_in_filter,
num_filters,
stride,
filter_size,
padding,
expansion_factor, ):
super(InvertedResidualUnit, self).__init__()
num_expfilter = int(round(num_in_filter * expansion_factor))
self._expand_conv = ConvBNLayer(
num_channels=num_channels,
num_filters=num_expfilter,
filter_size=1,
stride=1,
padding=0,
num_groups=1)
self._bottleneck_conv = ConvBNLayer(
num_channels=num_expfilter,
num_filters=num_expfilter,
filter_size=filter_size,
stride=stride,
padding=padding,
num_groups=num_expfilter,
use_cudnn=False)
self._linear_conv = ConvBNLayer(
num_channels=num_expfilter,
num_filters=num_filters,
filter_size=1,
stride=1,
padding=0,
num_groups=1)
def forward(self, inputs, ifshortcut):
y = self._expand_conv(inputs, if_act=True)
y = self._bottleneck_conv(y, if_act=True)
y = self._linear_conv(y, if_act=False)
if ifshortcut:
y = fluid.layers.elementwise_add(inputs, y)
return y
class InvresiBlocks(fluid.dygraph.Layer):
def __init__(self, in_c, t, c, n, s):
super(InvresiBlocks, self).__init__()
self._first_block = InvertedResidualUnit(
num_channels=in_c,
num_in_filter=in_c,
num_filters=c,
stride=s,
filter_size=3,
padding=1,
expansion_factor=t)
self._inv_blocks = []
for i in range(1, n):
tmp = self.add_sublayer(
sublayer=InvertedResidualUnit(
num_channels=c,
num_in_filter=c,
num_filters=c,
stride=1,
filter_size=3,
padding=1,
expansion_factor=t),
name=self.full_name() + "_" + str(i + 1))
self._inv_blocks.append(tmp)
def forward(self, inputs):
y = self._first_block(inputs, ifshortcut=False)
for inv_block in self._inv_blocks:
y = inv_block(y, ifshortcut=True)
return y
class MobileNetV2(fluid.dygraph.Layer):
"""MobileNetV2 model from
`"MobileNetV2: Inverted Residuals and Linear Bottlenecks" <https://arxiv.org/abs/1801.04381>`_.
Args:
scale (float): scale of channels in each layer. Default: 1.0.
num_classes (int): output dim of last fc layer. If num_classes <=0, last fc layer
will not be defined. Default: 1000.
with_pool (bool): use pool before the last fc layer or not. Default: True.
classifier_activation (str): activation for the last fc layer. Default: 'softmax'.
Examples:
.. code-block:: python
from paddle.vision.models import MobileNetV2
model = MobileNetV2()
"""
def __init__(self,
scale=1.0,
num_classes=1000,
with_pool=True,
classifier_activation='softmax'):
super(MobileNetV2, self).__init__()
self.scale = scale
self.num_classes = num_classes
self.with_pool = with_pool
bottleneck_params_list = [
(1, 16, 1, 1),
(6, 24, 2, 2),
(6, 32, 3, 2),
(6, 64, 4, 2),
(6, 96, 3, 1),
(6, 160, 3, 2),
(6, 320, 1, 1),
]
self._conv1 = ConvBNLayer(
num_channels=3,
num_filters=int(32 * scale),
filter_size=3,
stride=2,
padding=1)
self._invl = []
i = 1
in_c = int(32 * scale)
for layer_setting in bottleneck_params_list:
t, c, n, s = layer_setting
i += 1
tmp = self.add_sublayer(
sublayer=InvresiBlocks(
in_c=in_c, t=t, c=int(c * scale), n=n, s=s),
name='conv' + str(i))
self._invl.append(tmp)
in_c = int(c * scale)
self._out_c = int(1280 * scale) if scale > 1.0 else 1280
self._conv9 = ConvBNLayer(
num_channels=in_c,
num_filters=self._out_c,
filter_size=1,
stride=1,
padding=0)
if with_pool:
self._pool2d_avg = Pool2D(pool_type='avg', global_pooling=True)
if num_classes > 0:
tmp_param = ParamAttr(name=self.full_name() + "fc10_weights")
self._fc = Linear(
self._out_c,
num_classes,
act=classifier_activation,
param_attr=tmp_param,
bias_attr=ParamAttr(name="fc10_offset"))
def forward(self, inputs):
y = self._conv1(inputs, if_act=True)
for inv in self._invl:
y = inv(y)
y = self._conv9(y, if_act=True)
if self.with_pool:
y = self._pool2d_avg(y)
if self.num_classes > 0:
y = fluid.layers.reshape(y, shape=[-1, self._out_c])
y = self._fc(y)
return y
def _mobilenet(arch, pretrained=False, **kwargs):
model = MobileNetV2(**kwargs)
if pretrained:
assert arch in model_urls, "{} model do not have a pretrained model now, you should set pretrained=False".format(
arch)
weight_path = get_weights_path_from_url(model_urls[arch][0],
model_urls[arch][1])
assert weight_path.endswith(
'.pdparams'), "suffix of weight must be .pdparams"
param, _ = fluid.load_dygraph(weight_path)
model.load_dict(param)
return model
def mobilenet_v2(pretrained=False, scale=1.0, **kwargs):
"""MobileNetV2
Args:
pretrained (bool): If True, returns a model pre-trained on ImageNet. Default: False.
scale: (float): scale of channels in each layer. Default: 1.0.
Examples:
.. code-block:: python
from paddle.vision.models import mobilenet_v2
# build model
model = mobilenet_v2()
# build model and load imagenet pretrained weight
# model = mobilenet_v2(pretrained=True)
# build mobilenet v2 with scale=0.5
model = mobilenet_v2(scale=0.5)
"""
model = _mobilenet(
'mobilenetv2_' + str(scale), pretrained, scale=scale, **kwargs)
return model