【人工智能实验】卷积神经网络cnn框架的实现与应用-手写数字识别_y_true和y_pred
时间: 2023-09-19 14:02:00 浏览: 60
在卷积神经网络(CNN)框架的实现与应用中,手写数字识别是一个常见的应用场景。在这个任务中,我们需要通过训练一个CNN模型,将手写数字图像的真实标签(y_true)与模型预测输出的标签(y_pred)进行比较。
首先,我们需要收集一组带有已知标签的手写数字图像作为训练数据集。这些图像将被用作CNN模型的输入,并与其对应的标签进行关联。例如,对于一个数字为5的手写图像,我们将其与标签5进行关联。
然后,我们使用训练数据集对CNN模型进行训练。通过不断调整卷积层、池化层和全连接层等组件的参数,使模型能够准确地预测手写数字的标签。训练完成后,我们得到了一个经过优化的CNN模型。
接下来,我们将使用测试数据集作为输入,通过CNN模型进行预测。针对每个输入图像,模型将输出一个数字作为预测结果(y_pred)。与此同时,测试数据集中每个图像都有其真实标签(y_true)。我们将y_true与y_pred进行比较,以评估模型的准确性。
为了评估模型的性能,我们可以计算准确率(accuracy)。准确率指的是模型在所有测试样本中正确分类的比例。我们可以将模型正确预测的样本数量除以总样本数量来计算准确率。
总之,卷积神经网络框架的实现与应用中,手写数字识别任务包括收集并关联真实标签(y_true)和模型预测结果(y_pred),通过训练模型来使y_pred与y_true尽可能一致,并通过准确率等指标评估模型的性能。
相关问题
使用PyTorch构建卷积神经网络(CNN)来训练图像分类器,识别手写数字
好的,以下是使用PyTorch构建卷积神经网络(CNN)来训练图像分类器,识别手写数字的步骤:
1. 导入必要的库和数据集
```python
import torch
import torch.nn as nn
import torch.optim as optim
import torchvision
import torchvision.transforms as transforms
# 加载手写数字数据集
train_dataset = torchvision.datasets.MNIST(root='./data', train=True, transform=transforms.ToTensor(), download=True)
test_dataset = torchvision.datasets.MNIST(root='./data', train=False, transform=transforms.ToTensor(), download=True)
# 定义批次大小
batch_size = 128
# 加载数据
train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=batch_size, shuffle=True)
test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=batch_size, shuffle=False)
```
2. 定义CNN模型
```python
class CNN(nn.Module):
def __init__(self):
super(CNN, self).__init__()
self.conv1 = nn.Conv2d(1, 32, 5, padding=2)
self.conv2 = nn.Conv2d(32, 64, 5, padding=2)
self.pool = nn.MaxPool2d(2)
self.fc1 = nn.Linear(64*7*7, 1024)
self.fc2 = nn.Linear(1024, 10)
self.dropout = nn.Dropout(p=0.5)
self.relu = nn.ReLU()
def forward(self, x):
x = self.conv1(x)
x = self.relu(x)
x = self.pool(x)
x = self.conv2(x)
x = self.relu(x)
x = self.pool(x)
x = x.view(-1, 64*7*7)
x = self.fc1(x)
x = self.relu(x)
x = self.dropout(x)
x = self.fc2(x)
return x
# 实例化模型
model = CNN()
```
3. 定义损失函数和优化器
```python
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=0.001)
```
4. 训练模型
```python
# 定义训练函数
def train(model, train_loader, criterion, optimizer, epoch):
model.train()
for batch_idx, (data, target) in enumerate(train_loader):
optimizer.zero_grad()
output = model(data)
loss = criterion(output, target)
loss.backward()
optimizer.step()
if batch_idx % 100 == 0:
print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format(
epoch, batch_idx * len(data), len(train_loader.dataset),
100. * batch_idx / len(train_loader), loss.item()))
# 定义测试函数
def test(model, test_loader, criterion):
model.eval()
test_loss, correct = 0, 0
with torch.no_grad():
for data, target in test_loader:
output = model(data)
test_loss += criterion(output, target).item()
pred = output.argmax(dim=1, keepdim=True)
correct += pred.eq(target.view_as(pred)).sum().item()
test_loss /= len(test_loader.dataset)
print('Test set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n'.format(
test_loss, correct, len(test_loader.dataset),
100. * correct / len(test_loader.dataset)))
# 训练模型
for epoch in range(1, 11):
train(model, train_loader, criterion, optimizer, epoch)
test(model, test_loader, criterion)
```
5. 测试模型
```python
# 加载测试数据
test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=1, shuffle=True)
# 预测一张手写数字图片
model.eval()
with torch.no_grad():
for data, target in test_loader:
output = model(data)
print('Predicted Label:', output.argmax(dim=1).item())
break
```
希望这个例子能对您有所帮助!
TensorFlow基于卷积神经网络的手写数字图像识别代码实现
这是一个基于TensorFlow框架实现的手写数字图像识别代码,使用的是卷积神经网络(CNN)模型。
首先,导入需要的库:
```
import tensorflow as tf
from tensorflow.examples.tutorials.mnist import input_data
```
然后,定义一些常量和超参数:
```
learning_rate = 0.001
training_epochs = 15
batch_size = 100
n_classes = 10
dropout = 0.75
# 输入数据的维度
n_input = 784 # 28*28
```
接着,定义占位符:
```
x = tf.placeholder(tf.float32, [None, n_input])
y = tf.placeholder(tf.float32, [None, n_classes])
keep_prob = tf.placeholder(tf.float32)
```
定义卷积层和池化层函数:
```
def conv2d(x, W, b, strides=1):
x = tf.nn.conv2d(x, W, strides=[1, strides, strides, 1], padding='SAME')
x = tf.nn.bias_add(x, b)
return tf.nn.relu(x)
def maxpool2d(x, k=2):
return tf.nn.max_pool(x, ksize=[1, k, k, 1], strides=[1, k, k, 1], padding='SAME')
```
接下来,定义卷积神经网络模型:
```
def conv_net(x, weights, biases, dropout):
x = tf.reshape(x, shape=[-1, 28, 28, 1])
# 第一层卷积层
conv1 = conv2d(x, weights['wc1'], biases['bc1'])
conv1 = maxpool2d(conv1, k=2)
# 第二层卷积层
conv2 = conv2d(conv1, weights['wc2'], biases['bc2'])
conv2 = maxpool2d(conv2, k=2)
# 全连接层
fc1 = tf.reshape(conv2, [-1, weights['wd1'].get_shape().as_list()[0]])
fc1 = tf.add(tf.matmul(fc1, weights['wd1']), biases['bd1'])
fc1 = tf.nn.relu(fc1)
fc1 = tf.nn.dropout(fc1, dropout)
# 输出层
out = tf.add(tf.matmul(fc1, weights['out']), biases['out'])
return out
```
然后,初始化权重和偏置:
```
weights = {
'wc1': tf.Variable(tf.random_normal([5, 5, 1, 32])),
'wc2': tf.Variable(tf.random_normal([5, 5, 32, 64])),
'wd1': tf.Variable(tf.random_normal([7*7*64, 1024])),
'out': tf.Variable(tf.random_normal([1024, n_classes]))
}
biases = {
'bc1': tf.Variable(tf.random_normal([32])),
'bc2': tf.Variable(tf.random_normal([64])),
'bd1': tf.Variable(tf.random_normal([1024])),
'out': tf.Variable(tf.random_normal([n_classes]))
}
```
接着,定义损失函数和优化器:
```
pred = conv_net(x, weights, biases, keep_prob)
cost = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits=pred, labels=y))
optimizer = tf.train.AdamOptimizer(learning_rate=learning_rate).minimize(cost)
```
定义评估模型的准确率函数:
```
correct_pred = tf.equal(tf.argmax(pred, 1), tf.argmax(y, 1))
accuracy = tf.reduce_mean(tf.cast(correct_pred, tf.float32))
```
最后,训练模型:
```
mnist = input_data.read_data_sets('/tmp/data/', one_hot=True)
with tf.Session() as sess:
sess.run(tf.global_variables_initializer())
# 训练循环
for epoch in range(training_epochs):
avg_cost = 0.
total_batch = int(mnist.train.num_examples/batch_size)
# 遍历所有批次(batch)
for i in range(total_batch):
batch_x, batch_y = mnist.train.next_batch(batch_size)
# 运行优化器
sess.run(optimizer, feed_dict={x: batch_x, y: batch_y, keep_prob: dropout})
# 计算损失值
avg_cost += sess.run(cost, feed_dict={x: batch_x, y: batch_y, keep_prob: 1.}) / total_batch
# 显示每一轮训练的结果
if epoch % 1 == 0:
print("Epoch:", '%04d' % (epoch+1), "cost=", "{:.9f}".format(avg_cost))
# 计算测试数据的准确率
print("Accuracy:", accuracy.eval({x: mnist.test.images, y: mnist.test.labels, keep_prob: 1.}))
```
这样,一个基于TensorFlow框架实现的手写数字图像识别代码就完成了。