使用MindSpore框架实现一个卷积神经网络,用于手写字体识别的任务,代码
时间: 2024-02-23 22:02:18 浏览: 143
好的,以下是使用MindSpore框架实现手写字体识别的卷积神经网络的代码:
```python
import mindspore.nn as nn
import mindspore.ops as ops
from mindspore import Tensor
class Net(nn.Cell):
def __init__(self):
super(Net, self).__init__()
self.conv1 = nn.Conv2d(in_channels=1, out_channels=32, kernel_size=5, stride=1, padding=0)
self.relu1 = nn.ReLU()
self.pool1 = nn.MaxPool2d(kernel_size=2, stride=2)
self.conv2 = nn.Conv2d(in_channels=32, out_channels=64, kernel_size=5, stride=1, padding=0)
self.relu2 = nn.ReLU()
self.pool2 = nn.MaxPool2d(kernel_size=2, stride=2)
self.flatten = nn.Flatten()
self.fc1 = nn.Dense(in_channels=1024, out_channels=256)
self.relu3 = nn.ReLU()
self.fc2 = nn.Dense(in_channels=256, out_channels=10)
def construct(self, x):
x = self.conv1(x)
x = self.relu1(x)
x = self.pool1(x)
x = self.conv2(x)
x = self.relu2(x)
x = self.pool2(x)
x = self.flatten(x)
x = self.fc1(x)
x = self.relu3(x)
x = self.fc2(x)
return x
```
其中,我们定义了一个名为Net的类,继承自MindSpore的nn.Cell类。在该类的构造函数中,我们定义了卷积层、激活函数、池化层以及全连接层等模块,这些模块构成了我们的卷积神经网络。在该类的construct方法中,我们按照卷积层、激活函数、池化层、全连接层的顺序依次调用这些模块,最终返回网络的输出。
接下来,我们可以使用该网络来训练和测试手写字体识别模型,以下是一个简单的训练过程:
```python
import mindspore.dataset as ds
import mindspore.dataset.transforms.c_transforms as C
from mindspore import Model, context
from mindspore.train.callback import LossMonitor
from mindspore.nn import SoftmaxCrossEntropyWithLogits
context.set_context(mode=context.GRAPH_MODE, device_target="CPU")
BATCH_SIZE = 32
EPOCH_SIZE = 10
DATA_DIR = "./data"
train_ds = ds.MnistDataset(DATA_DIR, num_samples=60000, shuffle=True)
train_ds = train_ds.map(input_columns="image", operations=C.TypeCast(mstype.float32))
train_ds = train_ds.map(input_columns="label", operations=C.TypeCast(mstype.int32))
train_ds = train_ds.batch(BATCH_SIZE, drop_remainder=True)
test_ds = ds.MnistDataset(DATA_DIR, num_samples=10000, shuffle=False)
test_ds = test_ds.map(input_columns="image", operations=C.TypeCast(mstype.float32))
test_ds = test_ds.map(input_columns="label", operations=C.TypeCast(mstype.int32))
test_ds = test_ds.batch(BATCH_SIZE, drop_remainder=True)
net = Net()
criterion = SoftmaxCrossEntropyWithLogits(sparse=True, reduction='mean')
optimizer = nn.Adam(params=net.trainable_params())
model = Model(net, loss_fn=criterion, optimizer=optimizer, metrics={"acc"})
model.train(EPOCH_SIZE, train_ds, callbacks=[LossMonitor()], dataset_sink_mode=False)
```
首先,我们设置MindSpore的运行环境为图模式(context.GRAPH_MODE),并且指定设备为CPU。接着,我们定义了一些超参数,如BATCH_SIZE和EPOCH_SIZE,以及数据集的路径DATA_DIR。然后,我们使用MindSpore中的MnistDataset类来加载MNIST数据集,并且对数据进行预处理,包括类型转换、数据增强等操作。接着,我们定义了一个Net实例以及损失函数、优化器等模型训练所需的模块。最后,我们使用MindSpore中的Model类来创建一个模型实例,然后调用train方法来开始模型的训练过程,其中,我们还使用LossMonitor回调函数来监控模型的训练损失。
阅读全文