ShuffleNet V1
时间: 2023-12-04 11:36:46 浏览: 42
ShuffleNet V1 是一种轻量级的神经网络模型,用于图像分类任务。它在2017年由CSDN开发并发布。ShuffleNet V1 的设计目的是在保持较高准确率的同时,降低模型的计算复杂度和参数量。
ShuffleNet V1 的核心思想是通过引入逐通道随机混洗操作(channel shuffle),将卷积网络中的分组卷积操作与通道之间的信息交互相结合。这种混洗操作可以减少模型中的参数量,提高模型的计算效率。同时,ShuffleNet V1 还采用了一种特殊的分组卷积方式,即将输入通道分成若干组,使得每个组内的通道之间可以相互交互,而不同组之间的通道则没有直接的连接。
通过上述设计,ShuffleNet V1 在保持较高准确率的情况下,大大减少了模型的计算复杂度和内存消耗。它在移动设备和嵌入式场景中具有广泛的应用前景。
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ShuffleNet v1模型
ShuffleNet v1是一种轻量级的卷积神经网络模型,旨在在计算资源受限的设备上实现高效的图像分类任务。它被设计为在保持较高准确性的同时减少模型的计算和内存消耗。
ShuffleNet v1的核心思想是引入了逐通道组卷积和通道重排操作。逐通道组卷积将输入特征图按通道进行分组,每个组内的通道进行独立的卷积操作,然后将不同组的结果按顺序拼接起来。通过这样的方式,可以减少卷积运算的复杂度。
通道重排操作则用于增强信息流动性。它将输入特征图按照一定规则重新排列通道顺序,使得不同组之间可以有更多的信息交互,从而提高模型的表示能力。
ShuffleNet v1通过不断迭代逐渐减少模型的计算量。它使用了一系列逐层缩减通道数目和分辨率的策略,以实现更高效的特征提取和参数量的控制。
总体而言,ShuffleNet v1是一种在计算资源受限的情况下,能够实现较高准确性的轻量级模型。它在图像分类等任务上具有较好的性能,并且适合在嵌入式设备和移动设备等资源受限的环境中部署和应用。
shufflenetv1 pytorch代码
以下是ShuffleNetV1的PyTorch代码实现,包括ShuffleNetV1的网络结构和训练代码:
```python
import torch.nn as nn
import math
__all__ = ['ShuffleNetV1', 'shufflenetv1']
def conv3x3(in_planes, out_planes, stride=1):
"""3x3 convolution with padding"""
return nn.Conv2d(in_planes, out_planes, kernel_size=3, stride=stride,
padding=1, bias=False)
class BasicBlock(nn.Module):
def __init__(self, inplanes, planes, stride=1, downsample=None):
super(BasicBlock, self).__init__()
self.conv1 = conv3x3(inplanes, planes, stride)
self.bn1 = nn.BatchNorm2d(planes)
self.relu = nn.ReLU(inplace=True)
self.conv2 = conv3x3(planes, planes)
self.bn2 = nn.BatchNorm2d(planes)
self.downsample = downsample
self.stride = stride
def forward(self, x):
residual = x
out = self.conv1(x)
out = self.bn1(out)
out = self.relu(out)
out = self.conv2(out)
out = self.bn2(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
out = self.relu(out)
return out
class ShuffleNetV1(nn.Module):
def __init__(self, num_classes=1000, groups=3, width_mult=1):
super(ShuffleNetV1, self).__init__()
self.groups = groups
self.stage_repeats = [3, 7, 3]
if groups == 1:
self.stage_out_channels = [-1, 24, 144, 288, 576]
elif groups == 2:
self.stage_out_channels = [-1, 24, 200, 400, 800]
elif groups == 3:
self.stage_out_channels = [-1, 24, 240, 480, 960]
elif groups == 4:
self.stage_out_channels = [-1, 24, 272, 544, 1088]
elif groups == 8:
self.stage_out_channels = [-1, 24, 384, 768, 1536]
else:
raise ValueError("""{} groups is not supported for
1x1 Grouped Convolutions""".format(num_groups))
# building first layer
input_channels = 3
output_channels = self.stage_out_channels[1]
output_channels = int(output_channels * width_mult)
self.conv1 = nn.Conv2d(input_channels, output_channels, kernel_size=3, stride=2, padding=1, bias=False)
self.bn1 = nn.BatchNorm2d(output_channels)
self.relu = nn.ReLU(inplace=True)
self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
# building stages
self.stage2 = self._make_stage(2, width_mult)
self.stage3 = self._make_stage(3, width_mult)
self.stage4 = self._make_stage(4, width_mult)
# building last several layers
self.conv_last = nn.Conv2d(self.stage_out_channels[-2], self.stage_out_channels[-1], kernel_size=1, stride=1, padding=0, bias=False)
self.globalpool = nn.AvgPool2d(7)
self.fc = nn.Linear(self.stage_out_channels[-1], num_classes)
def _make_stage(self, stage, width_mult):
modules = OrderedDict()
stage_name = "ShuffleUnit_Stage{}".format(stage)
# stage_repeats = self.stage_repeats[stage]
unit1 = ShuffleUnit(self.stage_out_channels[stage-1], self.stage_out_channels[stage], 2, groups=self.groups, width_mult=width_mult)
modules[stage_name+"_unit1"] = unit1
for i in range(self.stage_repeats[stage-2]):
name = stage_name + "_unit" + str(i+2)
module = ShuffleUnit(self.stage_out_channels[stage], self.stage_out_channels[stage], 1, groups=self.groups, width_mult=width_mult)
modules[name] = module
return nn.Sequential(modules)
def forward(self, x):
x = self.conv1(x)
x = self.bn1(x)
x = self.relu(x)
x = self.maxpool(x)
x = self.stage2(x)
x = self.stage3(x)
x = self.stage4(x)
x = self.conv_last(x)
x = self.globalpool(x)
x = x.view(-1, self.stage_out_channels[-1])
x = self.fc(x)
return x
class ShuffleUnit(nn.Module):
def __init__(self, in_channels, out_channels, stride, groups=3, width_mult=1):
super(ShuffleUnit, self).__init__()
if stride != 1 or in_channels != out_channels:
self.use_res_connect = False
self.shortcut = nn.Sequential(
nn.Conv2d(in_channels, in_channels, kernel_size=3, stride=stride, padding=1, groups=in_channels, bias=False),
nn.BatchNorm2d(in_channels),
nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=1, padding=0, bias=False),
nn.BatchNorm2d(out_channels),
nn.ReLU(inplace=True),
)
else:
self.use_res_connect = True
self.shortcut = nn.Sequential()
self.groups = groups
mid_channels = int(out_channels / 4 * width_mult)
self.conv1 = nn.Conv2d(in_channels, mid_channels, kernel_size=1, stride=1, padding=0, bias=False)
self.bn1 = nn.BatchNorm2d(mid_channels)
self.conv2 = nn.Conv2d(mid_channels, mid_channels, kernel_size=3, stride=stride, padding=1, groups=groups, bias=False)
self.bn2 = nn.BatchNorm2d(mid_channels)
self.conv3 = nn.Conv2d(mid_channels, out_channels, kernel_size=1, stride=1, padding=0, bias=False)
self.bn3 = nn.BatchNorm2d(out_channels)
self.relu = nn.ReLU(inplace=True)
def _channel_shuffle(self, x, groups):
batchsize, num_channels, height, width = x.data.size()
channels_per_group = num_channels // groups
x = x.view(batchsize, groups, channels_per_group, height, width)
x = torch.transpose(x, 1, 2).contiguous()
x = x.view(batchsize, -1, height, width)
return x
def forward(self, x):
if self.use_res_connect:
shortcut = x
x = self.conv1(x)
x = self.bn1(x)
x = self.relu(x)
x = self.conv2(x)
x = self.bn2(x)
x = self.relu(x)
x = self._channel_shuffle(x, self.groups)
x = self.conv3(x)
x = self.bn3(x)
if self.use_res_connect:
shortcut = self.shortcut(shortcut)
x += shortcut
x = self.relu(x)
return x
def shufflenetv1(**kwargs):
"""
Constructs a ShuffleNetV1 model
"""
return ShuffleNetV1(**kwargs)
```
在使用ShuffleNetV1时,可以通过以下方式进行实例化:
```python
import torch
from shufflenetv1 import shufflenetv1
model = shufflenetv1(groups=3, width_mult=1)
input = torch.randn(1, 3, 224, 224)
output = model(input)
print(output.shape)
```
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