# Copyright 2021 Huawei Technologies Co., Ltd
#
# 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
from scipy.stats import truncnorm
import tinyms as ts
from tinyms import layers, Tensor
from tinyms.primitives import tensor_add, ReduceMean
def _conv_variance_scaling_initializer(in_channel, out_channel, kernel_size):
fan_in = in_channel * kernel_size * kernel_size
scale = 1.0
scale /= max(1., fan_in)
stddev = (scale ** 0.5) / .87962566103423978
mu, sigma = 0, stddev
weight = truncnorm(-2, 2, loc=mu, scale=sigma).rvs(out_channel * in_channel * kernel_size * kernel_size)
return ts.reshape(weight, (out_channel, in_channel, kernel_size, kernel_size))
def _weight_variable(shape, factor=0.01):
init_value = np.random.randn(*shape).astype(np.float32) * factor
return Tensor(init_value)
def _conv3x3(in_channel, out_channel, stride=1):
weight_shape = (out_channel, in_channel, 3, 3)
weight = _weight_variable(weight_shape)
return layers.Conv2d(in_channel, out_channel,
kernel_size=3, stride=stride, padding=0, pad_mode='same', weight_init=weight)
def _conv1x1(in_channel, out_channel, stride=1):
weight_shape = (out_channel, in_channel, 1, 1)
weight = _weight_variable(weight_shape)
return layers.Conv2d(in_channel, out_channel,
kernel_size=1, stride=stride, padding=0, pad_mode='same', weight_init=weight)
def _conv7x7(in_channel, out_channel, stride=1):
weight_shape = (out_channel, in_channel, 7, 7)
weight = _weight_variable(weight_shape)
return layers.Conv2d(in_channel, out_channel,
kernel_size=7, stride=stride, padding=0, pad_mode='same', weight_init=weight)
def _bn(channel):
return layers.BatchNorm2d(channel, eps=1e-4, momentum=0.9,
gamma_init=1, beta_init=0, moving_mean_init=0, moving_var_init=1)
def _bn_last(channel):
return layers.BatchNorm2d(channel, eps=1e-4, momentum=0.9,
gamma_init=0, beta_init=0, moving_mean_init=0, moving_var_init=1)
def _fc(in_channel, out_channel):
weight_shape = (out_channel, in_channel)
weight = _weight_variable(weight_shape)
return layers.Dense(in_channel, out_channel, has_bias=True, weight_init=weight, bias_init=0)
class ResidualBlock(layers.Layer):
"""
ResNet V1 residual block definition.
Args:
in_channel (int): Input channel.
out_channel (int): Output channel.
stride (int): Stride size for the first convolutional layer. Default: 1.
Returns:
Tensor, output tensor.
Examples:
>>> ResidualBlock(3, 256, stride=2)
"""
expansion = 4
def __init__(self, in_channel, out_channel, stride=1):
super(ResidualBlock, self).__init__()
channel = out_channel // self.expansion
self.conv1 = _conv1x1(in_channel, channel, stride=1)
self.bn1 = _bn(channel)
self.conv2 = _conv3x3(channel, channel, stride=stride)
self.bn2 = _bn(channel)
self.conv3 = _conv1x1(channel, out_channel, stride=1)
self.bn3 = _bn_last(out_channel)
self.relu = layers.ReLU()
self.down_sample = False
self.down_sample_layer = None
if stride != 1 or in_channel != out_channel:
self.down_sample = True
if self.down_sample:
self.down_sample_layer = layers.SequentialLayer(
[_conv1x1(in_channel, out_channel, stride), _bn(out_channel)])
def construct(self, x):
out = self.relu(self.bn1(self.conv1(x)))
out = self.relu(self.bn2(self.conv2(out)))
out = self.bn3(self.conv3(out))
identity = x
if self.down_sample:
identity = self.down_sample_layer(identity)
out = self.relu(tensor_add(out, identity))
return out
[文档]class ResNet(layers.Layer):
"""
ResNet architecture.
Args:
block (layers.Layer): Block for network.
layer_nums (list): Numbers of block in different layers.
in_channels (list): Input channel in each layer.
out_channels (list): Output channel in each layer.
strides (list): Stride size in each layer.
num_classes (int): The number of classes that the training images are belonging to.
Returns:
Tensor, output tensor.
Examples:
>>> ResNet(ResidualBlock,
>>> [3, 4, 6, 3],
>>> [64, 256, 512, 1024],
>>> [256, 512, 1024, 2048],
>>> [1, 2, 2, 2],
>>> 10)
"""
def __init__(self,
block,
layer_nums,
in_channels,
out_channels,
strides,
num_classes):
super(ResNet, self).__init__()
if not len(layer_nums) == len(in_channels) == len(out_channels) == 4:
raise ValueError("the length of layer_num, in_channels, out_channels list must be 4!")
self.conv1 = _conv7x7(3, 64, stride=2)
self.bn1 = _bn(64)
self.relu = layers.ReLU()
self.maxpool = layers.MaxPool2d(kernel_size=3, stride=2, pad_mode="same")
self.layer1 = self._make_layer(block,
layer_nums[0],
in_channel=in_channels[0],
out_channel=out_channels[0],
stride=strides[0])
self.layer2 = self._make_layer(block,
layer_nums[1],
in_channel=in_channels[1],
out_channel=out_channels[1],
stride=strides[1])
self.layer3 = self._make_layer(block,
layer_nums[2],
in_channel=in_channels[2],
out_channel=out_channels[2],
stride=strides[2])
self.layer4 = self._make_layer(block,
layer_nums[3],
in_channel=in_channels[3],
out_channel=out_channels[3],
stride=strides[3])
self.mean = ReduceMean(keep_dims=True)
self.flatten = layers.Flatten()
self.end_point = _fc(out_channels[3], num_classes)
def _make_layer(self, block, layer_num, in_channel, out_channel, stride):
"""
Make stage network of ResNet.
Args:
block (layers.Layer): Resnet block.
layer_num (int): Layer number.
in_channel (int): Input channel.
out_channel (int): Output channel.
stride (int): Stride size for the first convolutional layer.
Returns:
SequentialLayer, the output layer.
Examples:
>>> _make_layer(ResidualBlock, 3, 128, 256, 2)
"""
layer = layers.SequentialLayer([block(in_channel, out_channel, stride=stride)])
for _ in range(1, layer_num):
resnet_block = block(out_channel, out_channel, stride=1)
layer.append(resnet_block)
return layer
def construct(self, x):
c1 = self.maxpool(self.relu(self.bn1(self.conv1(x))))
c2 = self.layer1(c1)
c3 = self.layer2(c2)
c4 = self.layer3(c3)
c5 = self.layer4(c4)
out = self.end_point(self.flatten(self.mean(c5, (2, 3))))
return out
[文档]def resnet50(class_num=10):
"""
Get ResNet50 neural network.
Args:
class_num (int): Class number. Default: 10.
Returns:
layers.Layer, layer instance of ResNet50 neural network.
Examples:
>>> net = resnet50(10)
"""
return ResNet(ResidualBlock,
[3, 4, 6, 3],
[64, 256, 512, 1024],
[256, 512, 1024, 2048],
[1, 2, 2, 2],
class_num)