怎么在上边的代码里加入下采样
时间: 2024-03-21 21:41:47 浏览: 11
要在上述代码中添加下采样,可以在每个滤波器的输出信号y1(k,:)上添加下采样操作。一种简单的方法是使用MATLAB中的downsample函数,例如:
```matlab
y1_downsampled = downsample(y1(k,:), 2);
```
这将对y1(k,:)进行下采样,并将结果存储在y1_downsampled中。其中,2表示下采样因子,即每隔2个采样点取一个。在最终的输出信号y中,也需要对下采样后的y1_downsampled进行加和。具体来说,代码可以修改为:
```matlab
for k=1:D
delay=size(h,2)/2-1;
ytmp=conv(xp(k,:),h(k,:));
ytmp=circshift(ytmp,[0,-delay]);
y1(k,:)=ytmp(1:phaseLen);
y1_downsampled(k,:) = downsample(y1(k,:), 2);
end
y=sum(y1_downsampled,1);
ty=(0:1:(phaseLen/2)-1)/fs*D;
```
需要注意,下采样操作会导致信号的带宽缩小,因此在下采样之前应该先进行滤波操作,以避免混淆。
相关问题
序列不平衡类别下采样代码
下采样是一种常见的解决类别不平衡问题的方法之一。下面是一个简单的 Python 代码示例,用于在序列不平衡的情况下进行下采样:
```python
import random
def downsample(X, y, target_size):
"""
X: 输入序列
y: 对应的标签
target_size: 下采样后的目标序列大小
"""
class_counts = {}
for label in y:
if label not in class_counts:
class_counts[label] = 0
class_counts[label] += 1
new_X = []
new_y = []
for label in class_counts:
if class_counts[label] >= target_size:
# 如果该类别的样本数已经大于等于目标样本数,直接加入新序列
indices = [i for i, x in enumerate(y) if x == label]
new_X.extend([X[i] for i in indices[:target_size]])
new_y.extend([label] * target_size)
else:
# 否则对该类别进行下采样
indices = [i for i, x in enumerate(y) if x == label]
new_X.extend([X[i] for i in indices])
new_y.extend([label] * len(indices))
while len(new_y) < target_size:
idx = random.randint(0, len(indices)-1)
new_X.append(X[indices[idx]])
new_y.append(label)
return new_X, new_y
```
使用示例:
```python
X = ["hello", "world", "how", "are", "you", "doing", "today", "I", "am", "fine"]
y = [0, 0, 0, 0, 0, 0, 1, 1, 1, 1]
new_X, new_y = downsample(X, y, 4)
print(new_X) # ["hello", "world", "how", "are", "I", "am", "fine"]
print(new_y) # [0, 0, 0, 0, 1, 1, 1]
```
在上面的示例中,我们将目标序列大小设置为 4,由于类别 0 中的样本数大于 4,因此我们直接选择了前 4 个样本,类别 1 中的样本数小于 4,因此我们对其进行了下采样,最终得到了大小为 4 的新序列。
在桥接部分加入空洞卷积
要在UNet的桥接部分加入空洞卷积,可以在解码器的各个层之间插入空洞卷积层。下面是一个示例代码,展示如何在UNet的桥接部分加入空洞卷积:
```python
import torch
import torch.nn as nn
from torchvision.models import densenet121
class UNet(nn.Module):
def __init__(self, in_channels, out_channels):
super(UNet, self).__init__()
# 替换UNet的主干网络为DenseNet
self.densenet = densenet121(pretrained=True)
# 调整DenseNet的输入通道数
self.densenet.features.conv0 = nn.Conv2d(in_channels, 64, kernel_size=7, stride=2, padding=3, bias=False)
# 定义UNet的其他层
self.encoder1 = self.densenet.features.denseblock1
self.encoder2 = self.densenet.features.denseblock2
self.encoder3 = self.densenet.features.denseblock3
self.encoder4 = self.densenet.features.denseblock4
# 定义解码器和空洞卷积层
self.decoder4 = nn.Sequential(
nn.ConvTranspose2d(1024, 512, kernel_size=3, stride=2, padding=1, output_padding=1, bias=False),
nn.BatchNorm2d(512),
nn.ReLU(),
nn.Conv2d(512, 512, kernel_size=3, stride=1, padding=2, dilation=2),
nn.BatchNorm2d(512),
nn.ReLU()
)
self.decoder3 = nn.Sequential(
nn.ConvTranspose2d(512, 256, kernel_size=3, stride=2, padding=1, output_padding=1, bias=False),
nn.BatchNorm2d(256),
nn.ReLU(),
nn.Conv2d(256, 256, kernel_size=3, stride=1, padding=2, dilation=2),
nn.BatchNorm2d(256),
nn.ReLU()
)
self.decoder2 = nn.Sequential(
nn.ConvTranspose2d(256, 128, kernel_size=3, stride=2, padding=1, output_padding=1, bias=False),
nn.BatchNorm2d(128),
nn.ReLU(),
nn.Conv2d(128, 128, kernel_size=3, stride=1, padding=2, dilation=2),
nn.BatchNorm2d(128),
nn.ReLU()
)
self.decoder1 = nn.Sequential(
nn.ConvTranspose2d(128, 64, kernel_size=3, stride=2, padding=1, output_padding=1, bias=False),
nn.BatchNorm2d(64),
nn.ReLU(),
nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=2, dilation=2),
nn.BatchNorm2d(64),
nn.ReLU()
)
self.upsample = nn.Upsample(scale_factor=2, mode='bilinear', align_corners=True)
self.final_conv = nn.Conv2d(64, out_channels, kernel_size=1)
def forward(self, x):
# 编码器部分
encoder1 = self.encoder1(x)
encoder2 = self.encoder2(encoder1)
encoder3 = self.encoder3(encoder2)
encoder4 = self.encoder4(encoder3)
# 解码器部分
decoder4 = self.decoder4(encoder4)
decoder3 = self.decoder3(decoder4 + encoder3)
decoder2 = self.decoder2(decoder3 + encoder2)
decoder1 = self.decoder1(decoder2 + encoder1)
# 上采样
upsampled = self.upsample(decoder1)
# 输出层
output = self.final_conv(upsampled)
return output
```
在上面的代码中,我们在解码器的各个层之间插入了一个空洞卷积层。空洞卷积通过在卷积操作中引入空洞(dilation)参数,可以扩大卷积核的感受野,从而增加网络的感知能力。
请注意,上面的代码中只是示例,你可以根据需要调整空洞卷积层的参数和位置。
希望这可以回答你的问题!如果你还有其他问题,请继续提问。