resnet二分类实例
时间: 2023-10-21 17:04:47 浏览: 43
使用pytorch和resnet18模型进行图片二分类的全过程如下:
1. 下载并准备数据集,可以使用提供的蚂蚁蜜蜂分类数据集。
2. 加载预训练的resnet18模型,可以从提供的链接中下载。
3. 将模型最后一层的输出改为二分类的输出(例如使用nn.Linear将输出特征数改为2)。
4. 定义损失函数,例如使用交叉熵损失函数。
5. 定义优化器,例如使用随机梯度下降(SGD)优化器。
6. 将数据集划分为训练集和验证集,并定义数据加载器。
7. 进行训练和验证,使用训练集对模型进行训练,使用验证集对模型进行评估。
8. 可以选择保存训练好的模型以备将来使用。
相关问题
resnet-50实现代码
以下是 ResNet-50 的实现代码:
```python
import tensorflow as tf
def identity_block(X, f, filters, stage, block):
"""
实现恒等块
参数:
X -- 输入的张量,维度为 (m, n_H_prev, n_W_prev, n_C_prev)
f -- 整数,指定主路径中间的卷积窗口的形状
filters -- 整数列表,定义了主路径中每层的卷积层的过滤器数量
stage -- 整数,用于命名层,取决于它们在网络中的位置
block -- 字符串/整数,用于命名层,取决于它们在网络中的位置
返回:
X -- 恒等块的输出,维度为:(n_H, n_W, n_C)
"""
# 定义命名规则
conv_name_base = 'res' + str(stage) + block + '_branch'
bn_name_base = 'bn' + str(stage) + block + '_branch'
# 获取过滤器
F1, F2, F3 = filters
# 保存输入数据,将会用于为主路径添加捷径
X_shortcut = X
# 主路径的第一部分
X = tf.keras.layers.Conv2D(filters=F1, kernel_size=(1, 1), strides=(1, 1), padding='valid', name=conv_name_base + '2a', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '2a')(X)
X = tf.keras.layers.Activation('relu')(X)
# 主路径的第二部分
X = tf.keras.layers.Conv2D(filters=F2, kernel_size=(f, f), strides=(1, 1), padding='same', name=conv_name_base + '2b', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '2b')(X)
X = tf.keras.layers.Activation('relu')(X)
# 主路径的第三部分
X = tf.keras.layers.Conv2D(filters=F3, kernel_size=(1, 1), strides=(1, 1), padding='valid', name=conv_name_base + '2c', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '2c')(X)
# 主路径添加捷径
X = tf.keras.layers.Add()([X, X_shortcut])
X = tf.keras.layers.Activation('relu')(X)
return X
def convolutional_block(X, f, filters, stage, block, s=2):
"""
实现卷积块
参数:
X -- 输入的张量,维度为 (m, n_H_prev, n_W_prev, n_C_prev)
f -- 整数,指定主路径中间的卷积窗口的形状
filters -- 整数列表,定义了主路径中每层的卷积层的过滤器数量
stage -- 整数,用于命名层,取决于它们在网络中的位置
block -- 字符串/整数,用于命名层,取决于它们在网络中的位置
s -- 整数,指定要使用的步幅
返回:
X -- 卷积块的输出,维度为:(n_H, n_W, n_C)
"""
# 定义命名规则
conv_name_base = 'res' + str(stage) + block + '_branch'
bn_name_base = 'bn' + str(stage) + block + '_branch'
# 获取过滤器
F1, F2, F3 = filters
# 保存输入数据,将会用于为主路径添加捷径
X_shortcut = X
# 主路径的第一部分
X = tf.keras.layers.Conv2D(filters=F1, kernel_size=(1, 1), strides=(s, s), padding='valid', name=conv_name_base + '2a', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '2a')(X)
X = tf.keras.layers.Activation('relu')(X)
# 主路径的第二部分
X = tf.keras.layers.Conv2D(filters=F2, kernel_size=(f, f), strides=(1, 1), padding='same', name=conv_name_base + '2b', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '2b')(X)
X = tf.keras.layers.Activation('relu')(X)
# 主路径的第三部分
X = tf.keras.layers.Conv2D(filters=F3, kernel_size=(1, 1), strides=(1, 1), padding='valid', name=conv_name_base + '2c', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '2c')(X)
# 捷径路径
X_shortcut = tf.keras.layers.Conv2D(filters=F3, kernel_size=(1, 1), strides=(s, s), padding='valid', name=conv_name_base + '1', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X_shortcut)
X_shortcut = tf.keras.layers.BatchNormalization(axis=3, name=bn_name_base + '1')(X_shortcut)
# 主路径添加捷径
X = tf.keras.layers.Add()([X, X_shortcut])
X = tf.keras.layers.Activation('relu')(X)
return X
def ResNet50(input_shape=(64, 64, 3), classes=6):
"""
实现 ResNet-50
参数:
input_shape -- 输入的图像的维度
classes -- 整数,分类数
返回:
model -- Keras 模型实例
"""
# 定义输入作为 Keras 张量
X_input = tf.keras.layers.Input(input_shape)
# 零填充
X = tf.keras.layers.ZeroPadding2D((3, 3))(X_input)
# 第一阶段
X = tf.keras.layers.Conv2D(filters=64, kernel_size=(7, 7), strides=(2, 2), name='conv1', kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
X = tf.keras.layers.BatchNormalization(axis=3, name='bn_conv1')(X)
X = tf.keras.layers.Activation('relu')(X)
X = tf.keras.layers.MaxPooling2D(pool_size=(3, 3), strides=(2, 2))(X)
# 第二阶段
X = convolutional_block(X, f=3, filters=[64, 64, 256], stage=2, block='a', s=1)
X = identity_block(X, 3, [64, 64, 256], stage=2, block='b')
X = identity_block(X, 3, [64, 64, 256], stage=2, block='c')
# 第三阶段
X = convolutional_block(X, f=3, filters=[128, 128, 512], stage=3, block='a', s=2)
X = identity_block(X, 3, [128, 128, 512], stage=3, block='b')
X = identity_block(X, 3, [128, 128, 512], stage=3, block='c')
X = identity_block(X, 3, [128, 128, 512], stage=3, block='d')
# 第四阶段
X = convolutional_block(X, f=3, filters=[256, 256, 1024], stage=4, block='a', s=2)
X = identity_block(X, 3, [256, 256, 1024], stage=4, block='b')
X = identity_block(X, 3, [256, 256, 1024], stage=4, block='c')
X = identity_block(X, 3, [256, 256, 1024], stage=4, block='d')
X = identity_block(X, 3, [256, 256, 1024], stage=4, block='e')
X = identity_block(X, 3, [256, 256, 1024], stage=4, block='f')
# 第五阶段
X = convolutional_block(X, f=3, filters=[512, 512, 2048], stage=5, block='a', s=2)
X = identity_block(X, 3, [512, 512, 2048], stage=5, block='b')
X = identity_block(X, 3, [512, 512, 2048], stage=5, block='c')
# 平均池化层
X = tf.keras.layers.AveragePooling2D(pool_size=(2, 2), padding='same')(X)
# 输出层
X = tf.keras.layers.Flatten()(X)
X = tf.keras.layers.Dense(classes, activation='softmax', name='fc' + str(classes), kernel_initializer=tf.keras.initializers.glorot_uniform(seed=0))(X)
# 创建模型
model = tf.keras.models.Model(inputs=X_input, outputs=X, name='ResNet50')
return model
```
pytorch迁移学习实例
好的,以下是一个基于 PyTorch 的迁移学习实例,可以参考一下:
1. 导入必要的库
```python
import torch
import torch.nn as nn
import torchvision
from torchvision import datasets, models, transforms
import numpy as np
import matplotlib.pyplot as plt
```
2. 加载数据集
```python
data_dir = '/path/to/data'
data_transforms = {
'train': transforms.Compose([
transforms.RandomResizedCrop(224),
transforms.RandomHorizontalFlip(),
transforms.ToTensor(),
transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
]),
'val': transforms.Compose([
transforms.Resize(256),
transforms.CenterCrop(224),
transforms.ToTensor(),
transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
]),
}
image_datasets = {x: datasets.ImageFolder(os.path.join(data_dir, x), data_transforms[x])
for x in ['train', 'val']}
dataloaders = {x: torch.utils.data.DataLoader(image_datasets[x], batch_size=4,
shuffle=True, num_workers=4)
for x in ['train', 'val']}
dataset_sizes = {x: len(image_datasets[x]) for x in ['train', 'val']}
class_names = image_datasets['train'].classes
```
3. 加载预训练模型
```python
model_ft = models.resnet18(pretrained=True)
num_ftrs = model_ft.fc.in_features
model_ft.fc = nn.Linear(num_ftrs, 2)
```
4. 定义损失函数和优化器
```python
criterion = nn.CrossEntropyLoss()
# Observe that all parameters are being optimized
optimizer_ft = torch.optim.SGD(model_ft.parameters(), lr=0.001, momentum=0.9)
```
5. 训练模型
```python
def train_model(model, criterion, optimizer, num_epochs=25):
for epoch in range(num_epochs):
print('Epoch {}/{}'.format(epoch, num_epochs - 1))
print('-' * 10)
# Each epoch has a training and validation phase
for phase in ['train', 'val']:
if phase == 'train':
model.train() # Set model to training mode
else:
model.eval() # Set model to evaluate mode
running_loss = 0.0
running_corrects = 0
# Iterate over data.
for inputs, labels in dataloaders[phase]:
inputs = inputs.to(device)
labels = labels.to(device)
# zero the parameter gradients
optimizer.zero_grad()
# forward
# track history if only in train
with torch.set_grad_enabled(phase == 'train'):
outputs = model(inputs)
_, preds = torch.max(outputs, 1)
loss = criterion(outputs, labels)
# backward + optimize only if in training phase
if phase == 'train':
loss.backward()
optimizer.step()
# statistics
running_loss += loss.item() * inputs.size(0)
running_corrects += torch.sum(preds == labels.data)
epoch_loss = running_loss / dataset_sizes[phase]
epoch_acc = running_corrects.double() / dataset_sizes[phase]
print('{} Loss: {:.4f} Acc: {:.4f}'.format(
phase, epoch_loss, epoch_acc))
return model
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
model_ft = model_ft.to(device)
model_ft = train_model(model_ft, criterion, optimizer_ft, num_epochs=25)
```
6. 保存模型
```python
torch.save(model_ft.state_dict(), '/path/to/save/model.pth')
```
这个例子中,我们使用了一个预训练的 ResNet-18 模型进行迁移学习,然后训练了一个二分类模型。你可以根据自己的需要进行修改和扩展。