第一课时 基于MNIST数据集

import torch
from linear_net.load import load_data
import torch.utils.data as td

# 定义加载数据的函数，data_folder为保存gz数据的文件夹，该文件夹下有4个文件
# 'train-labels-idx1-ubyte.gz', 'train-images-idx3-ubyte.gz',
# 't10k-labels-idx1-ubyte.gz', 't10k-images-idx3-ubyte.gz'


(train_images, train_labels), (test_images, test_labels) = load_data()

X_train = torch.tensor(train_images / 255)
y_train = torch.tensor(train_labels).view(train_labels.shape[0], 1)
X_test = torch.tensor(test_images / 255)
y_test = torch.tensor(test_labels)


# y_train = torch.zeros(y_train.shape[0],10).scatter(dim=1,index=y_train.long(),src=torch.ones_like(y_train).float())
# print(y_train.shape)
# print(X_train.shape)

class MyDataset(td.Dataset):
    def __init__(self, d_t, d_l):
        self.data_tensor = d_t
        self.target_tensor = d_l

    def __getitem__(self, item):
        return self.data_tensor[item], self.target_tensor[item]

    def __len__(self):
        return self.data_tensor.size(0)


class FlattenLayer(torch.nn.Module):
    def __init__(self):
        super(FlattenLayer, self).__init__()

    def forward(self, x):
        return x.view(1, -1)


class Net(torch.nn.Module):
    def __init__(self):
        super(Net, self).__init__()
        self.flatten = FlattenLayer()
        self.linear_1 = torch.nn.Linear(28 * 28, 5)
        self.relu = torch.nn.ReLU()
        self.linear_2 = torch.nn.Linear(5, 10)
        self.softmax = torch.nn.Softmax(dim=1)
        # self.linear_1.weight.data.normal_(0.01,0.1)
        # self.linear_2.weight.data.normal_(0.01,0.1)
        # torch.nn.init.constant(self.linear_1.bias,0.0)
        # torch.nn.init.constant(self.linear_2.bias,0.0)

    def forward(self, x):
        x = self.flatten(x)
        x = self.relu(self.linear_1(x))
        x = self.linear_2(x)
        # print(x)
        return x


'''net = torch.nn.Sequential(
    OrderedDict([
        ('flatten', FlattenLayer()),
        ('linear_1', torch.nn.Linear(28 * 28, 5)),
        ('relu',torch.nn.ReLU()),
        ('linear_2', torch.nn.Linear(5, 10)),
        #('softmax',torch.nn.Softmax())
    ]))'''

net_t = Net()

train = MyDataset(X_train, y_train)
test = MyDataset(X_test.float(), y_test.long())

torch.nn.init.normal_(net_t.linear_1.weight, 0, std=0.1)
torch.nn.init.normal_(net_t.linear_2.weight, 0, std=0.1)
torch.nn.init.constant(net_t.linear_1.bias, 0)
torch.nn.init.constant(net_t.linear_2.bias, 0)

loss = torch.nn.CrossEntropyLoss()
optimizer = torch.optim.SGD(net_t.parameters(), lr=0.01)

data_loader = td.DataLoader(train, batch_size=200, shuffle=True)
# print(net_t)
correct = 0
for i, data in enumerate(test):
    inputs, label = data
    outputs = net_t(inputs)
    _, index = torch.max(outputs, 1)
    if index[0].long() == y_test[i].long():
        correct += 1

print(correct / y_test.shape[0])
for epoch in range(2):
    running_loss = 0.0
    for i, data in enumerate(train):
        net_t.zero_grad()
        inputs, label = data
        # inputs = inputs.float()
        optimizer.zero_grad()
        outputs = net_t(inputs.float())
        # print(label)
        # print(outputs)
        l = loss(outputs, label.long())
        l.requires_grad_()
        l.retain_grad()
        # print(l)
        l.backward()
        w1, b1 = net_t.linear_1.parameters()
        # print(w1.grad.sum())

        running_loss += l.item()

        optimizer.step()

    print(running_loss / len(train))
    print(running_loss)

correct = 0
for i, data in enumerate(test):
    inputs, label = data
    outputs = net_t(inputs)
    _, index = torch.max(outputs, 1)
    if index[0].long() == y_test[i].long():
        correct += 1


print(correct / y_test.shape[0])

import gzip
import os
import numpy as np

def load_data(data_folder=''):

  files = [
      'train-labels-idx1-ubyte.gz', 'train-images-idx3-ubyte.gz',
      't10k-labels-idx1-ubyte.gz', 't10k-images-idx3-ubyte.gz'
  ]

  paths = []
  for fname in files:
    paths.append(os.path.join(data_folder,fname))

  with gzip.open(paths[0], 'rb') as lbpath:
    y_train = np.frombuffer(lbpath.read(), np.uint8, offset=8)

  with gzip.open(paths[1], 'rb') as imgpath:
    x_train = np.frombuffer(
        imgpath.read(), np.uint8, offset=16).reshape(len(y_train), 28, 28)

  with gzip.open(paths[2], 'rb') as lbpath:
    y_test = np.frombuffer(lbpath.read(), np.uint8, offset=8)

  with gzip.open(paths[3], 'rb') as imgpath:
    x_test = np.frombuffer(
        imgpath.read(), np.uint8, offset=16).reshape(len(y_test), 28, 28)

  return (x_train, y_train), (x_test, y_test)

写了一下午呐，踩了好多坑，还是很有收获的，刚开始数据集都导不进来//????

这个是task1，

task2的传送门：https://blog.csdn.net/qq_16899143/article/details/104319470