基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)

基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)

  • 配置环境
  • 1.前言
  • 2.问题描述
  • 3.解决方案
  • 4.实现步骤
    • 4.1数据集选择
    • 4.2构建网络
    • 4.3训练网络
    • 4.4测试网络
    • 4.5图像预处理
    • 4.6传入网络进行计算
  • 5.代码实现
    • 5.1文件说明
    • 5.2使用方法
    • 5.3 训练模型
    • 5.4使用训练好的模型测试网络
    • 5.5调用摄像头实时检测
  • 6.附录
  • 7.结束语

配置环境

使用环境:python3.8
平台:Windows10
IDE:PyCharm

1.前言

手写数字识别,作为机器视觉入门项目,无论是基于传统的OpenCV方法还是基于目前火热的深度学习、神经网络的方法都有这不错的训练效果。当然,这个项目也常常被作为大学/研究生阶段的课程实验。可惜的是,目前网络上关于手写数字识别的项目代码很多,但是普遍不完整,对于初学者提出了不小的挑战。为此,博主撰写本文,无论你是希望借此完成课程实验或者学习机器视觉,本文或许对你都有帮助。

2.问题描述

本文针对的问题为:随机在黑板上写一个数字,通过调用电脑摄像头实时检测出数字是0-9哪个数字

3.解决方案

基于Python的深度学习方法:
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第1张图片
检测流程如下:
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第2张图片

4.实现步骤

4.1数据集选择

手写数字识别经典数据集:本文数据集选择的FishionMint数据集中的t10k,共含有一万张28*28的手写图片(二值图片)
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第3张图片
数据集下载地址见:https://github.com/ShakalakaPHD/Hand_wrtten/tree/master/dataset

4.2构建网络

采用Resnt(残差网络),残差网络的优势在于:

  • 更易捕捉模型细微波动
  • 更快的收敛速度
    基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第4张图片
    本文的网络结构如下图所示,代码见第五节:
    基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第5张图片

4.3训练网络

本文设置训练次数为100个循环,其实网络的训练过程是这样的:

  • 给网络模型“喂”数据(图像+标签)
  • 网络根据“喂”来的数据不断自我修正权重
  • 本文一共“喂”100次1万张图像
  • RTX2070上耗时2h
    训练结果如下:
    基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第6张图片

4.4测试网络

  • 随机选取数据集中37张图片进行检测
  • 正确率为36/37
  • 选取其中6张进行展示
    基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第7张图片

4.5图像预处理

基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第8张图片

  • 全部采取传统机器视觉的方法
  • 速度“飞快”,仅做以上操作处理速度高达200fps

4.6传入网络进行计算

  • 手写0-9的数字除了3识别不了其余均能识别
  • 检测速度高达60fps
    基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第9张图片
    基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第10张图片

5.代码实现

本文所有代码都已经上传至Github上https://github.com/ShakalakaPHD/Hand_wrtten/tree/master
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第11张图片

5.1文件说明

  • dataset文件夹存放的是训练数据集
  • logs文件夹为训练结束后权重文件所在
  • real_img、real_img_resize、test_imgs为用来测试的图片文件夹
  • 下面的py文件为本文代码

5.2使用方法

按照博主的环境配置自己的Python环境
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第12张图片
其中主要的包有:numpy、struct、matplotlib、OpenCV、Pytorch、torchvision、tqdm

5.3 训练模型

本文提供了训练好的模型,大家可以直接调用,已经上传至GitHub,如果不想训练的话,可以跳过训练这一步骤
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第13张图片
下面是训练的流程:

打开hand_wrtten_train.py文件,点击运行(博主使用的是PyCharm,大家根据自己喜好选择IDLE即可)
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第14张图片
值得注意的是,数据集路径需要修改为自己的路径,即这一段
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第15张图片
训练过程没报错会出现以下显示
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第16张图片
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第17张图片
训练得到的权重会保存在logs文件夹下
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第18张图片
模型训练需要时间,此时等待训练结束即可(RTX2070上训练了1h左右)

5.4使用训练好的模型测试网络

测试采用图片进行测试,代码见main_pthoto.py文件,使用方法与上面训练代码一直,代开后运行即可
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第19张图片
同样值得注意的是,main_pthoto.py文件中图片路径需要修改为自己的路径,即这一段
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第20张图片
以及predict.py文件中权重片路径需要修改为自己在5.3步中训练得到的.pth文件路径,如图所示
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第21张图片
运行结果如下

5.5调用摄像头实时检测

代码存在于main.py文件下,使用方法和5.4节图片检测一致,修改predict.py文件中权重片路径需要修改为自己在5.3步中训练得到的.pth文件路径,如图所示
基于卷积神经网络的手写数字识别(附数据集+完整代码+操作说明)_第22张图片
再运行main.py文件即可,可以看到载入网络模型后开始调用摄像头,并开始检测

6.附录

在此附上本文核心代码:
hand_wrtten_train.py


# author:Hurricane
# date:  2020/11/4
# E-mail:[email protected]

import numpy as np
import struct
import matplotlib.pyplot as plt
import cv2 as cv
import random
import torch
from torch import nn, optim
import torch.nn.functional as F
# import d2lzh_pytorch as d2l
import time
from tqdm import tqdm

# 训练集文件
train_images_idx3_ubyte_file = 'F:/PyCharm/Practice/hand_wrtten/dataset/train-images.idx3-ubyte'
# 训练集标签文件
train_labels_idx1_ubyte_file = 'F:/PyCharm/Practice/hand_wrtten/dataset/train-labels.idx1-ubyte'

# 测试集文件
test_images_idx3_ubyte_file = 'F:/PyCharm/Practice/hand_wrtten/dataset/t10k-images.idx3-ubyte'
# 测试集标签文件
test_labels_idx1_ubyte_file = 'F:/PyCharm/Practice/hand_wrtten/dataset/t10k-labels.idx1-ubyte'


# 读取数据部分
def decode_idx3_ubyte(idx3_ubyte_file):
    bin_data = open(idx3_ubyte_file, 'rb').read()

    offset = 0
    fmt_header = '>iiii'  # 因为数据结构中前4行的数据类型都是32位整型,所以采用i格式,但我们需要读取前4行数据,所以需要4个i。我们后面会看到标签集中,只使用2个ii。
    magic_number, num_images, num_rows, num_cols = struct.unpack_from(fmt_header, bin_data, offset)
    print('图片数量: %d张, 图片大小: %d*%d' % (num_images, num_rows, num_cols))

    # 解析数据集
    image_size = num_rows * num_cols
    offset += struct.calcsize(fmt_header)  # 获得数据在缓存中的指针位置,从前面介绍的数据结构可以看出,读取了前4行之后,指针位置(即偏移位置offset)指向0016。
    print(offset)
    fmt_image = '>' + str(
        image_size) + 'B'  # 图像数据像素值的类型为unsigned char型,对应的format格式为B。这里还有加上图像大小784,是为了读取784个B格式数据,如果没有则只会读取一个值(即一副图像中的一个像素值)
    print(fmt_image, offset, struct.calcsize(fmt_image))
    images = np.empty((num_images, 28, 28))
    # plt.figure()
    for i in tqdm(range(num_images)):
        image = np.array(struct.unpack_from(fmt_image, bin_data, offset)).reshape((num_rows, num_cols)).astype(np.uint8)
        # images[i] = cv.resize(image, (96, 96))
        images[i] = image
        # print(images[i])
        offset += struct.calcsize(fmt_image)

    return images


def decode_idx1_ubyte(idx1_ubyte_file):
    bin_data = open(idx1_ubyte_file, 'rb').read()
    offset = 0
    fmt_header = '>ii'
    magic_number, num_images = struct.unpack_from(fmt_header, bin_data, offset)
    print('图片数量: %d张' % (num_images))

    # 解析数据集
    offset += struct.calcsize(fmt_header)
    fmt_image = '>B'
    labels = np.empty(num_images)
    for i in tqdm(range(num_images)):
        labels[i] = struct.unpack_from(fmt_image, bin_data, offset)[0]
        offset += struct.calcsize(fmt_image)
    return labels


def load_train_images(idx_ubyte_file=train_images_idx3_ubyte_file):
    return decode_idx3_ubyte(idx_ubyte_file)


def load_train_labels(idx_ubyte_file=train_labels_idx1_ubyte_file):
    return decode_idx1_ubyte(idx_ubyte_file)


def load_test_images(idx_ubyte_file=test_images_idx3_ubyte_file):
    return decode_idx3_ubyte(idx_ubyte_file)


def load_test_labels(idx_ubyte_file=test_labels_idx1_ubyte_file):
    return decode_idx1_ubyte(idx_ubyte_file)


# 构建网络部分
class Residual(nn.Module):  # 本类已保存在d2lzh_pytorch包中方便以后使用
    def __init__(self, in_channels, out_channels, use_1x1conv=False, stride=1):
        super(Residual, self).__init__()
        self.conv1 = nn.Conv2d(in_channels, out_channels, kernel_size=3, padding=1, stride=stride)
        self.conv2 = nn.Conv2d(out_channels, out_channels, kernel_size=3, padding=1)
        if use_1x1conv:
            self.conv3 = nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=stride)
        else:
            self.conv3 = None
        self.bn1 = nn.BatchNorm2d(out_channels)
        self.bn2 = nn.BatchNorm2d(out_channels)

    def forward(self, X):
        Y = F.relu(self.bn1(self.conv1(X)))
        Y = self.bn2(self.conv2(Y))
        if self.conv3:
            X = self.conv3(X)
        return F.relu(Y + X)


class GlobalAvgPool2d(nn.Module):
    # 全局平均池化层可通过将池化窗口形状设置成输入的高和宽实现
    def __init__(self):
        super(GlobalAvgPool2d, self).__init__()

    def forward(self, x):
        return F.avg_pool2d(x, kernel_size=x.size()[2:])


def resnet_block(in_channels, out_channels, num_residuals, first_block=False):
    # num_residuals:残差数
    if first_block:
        assert in_channels == out_channels  # 第一个模块的通道数同输入通道数一致
    blk = []
    for i in range(num_residuals):
        if i == 0 and not first_block:
            blk.append(Residual(in_channels, out_channels, use_1x1conv=True, stride=2))
        else:
            blk.append(Residual(out_channels, out_channels))
    return nn.Sequential(*blk)


def evaluate_accuracy(img, label, net):
    device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
    acc_sum, n = 0.0, 0
    with torch.no_grad():
        X = torch.unsqueeze(img, 1)
        if isinstance(net, torch.nn.Module):
            net.eval()  # 评估模式, 这会关闭dropout
            acc_sum += (net(X.to(device)).argmax(dim=1) == label.to(device)).float().sum().cpu().item()
            net.train()  # 改回训练模式
        else:  # 自定义的模型, 3.13节之后不会用到, 不考虑GPU
            if ('is_training' in net.__code__.co_varnames):  # 如果有is_training这个参数
                # 将is_training设置成False
                acc_sum += (net(X, is_training=False).argmax(dim=1) == label).float().sum().item()
            else:
                acc_sum += (net(X).argmax(dim=1) == label).float().sum().item()
        n += label.shape[0]
    return acc_sum / n

class FlattenLayer(torch.nn.Module):
    def __init__(self):
        super(FlattenLayer, self).__init__()
    def forward(self, x): # x shape: (batch, *, *, ...)
        return x.view(x.shape[0], -1)

if __name__ == '__main__':
    print("train:")
    train_images_org = load_train_images().astype(np.float32)
    train_labels_org = load_train_labels().astype(np.int64)
    print("test")
    test_images = load_test_images().astype(np.float32)[0:1000]
    test_labels = load_test_labels().astype(np.int64)[0:1000]
    # 数据转换为Tensor
    train_images = torch.from_numpy(train_images_org)
    train_labels = torch.from_numpy(train_labels_org)
    test_images = torch.from_numpy(test_images)
    test_labels = torch.from_numpy(test_labels)
    # test_images = load_test_images()
    # test_labels = load_test_labels()

    # 查看前十个数据及其标签以读取是否正确
    for i in range(5):
        j = random.randint(0, 60000)
        print("now, show the number of image[{}]:".format(j), int(train_labels_org[j]))
        img = train_images_org[j]
        img = cv.resize(img, (600, 600))
        cv.imshow("image", img)
        cv.waitKey(0)
    cv.destroyAllWindows()
    print('all done!')
    print("*" * 50)

    # ResNet模型
    net = nn.Sequential(
        nn.Conv2d(1, 64, kernel_size=7, stride=2, padding=3),
        nn.BatchNorm2d(64),
        nn.ReLU(),
        nn.MaxPool2d(kernel_size=3, stride=2, padding=1))

    net.add_module("resnet_block1", resnet_block(64, 64, 2, first_block=True))
    net.add_module("resnet_block2", resnet_block(64, 128, 2))
    net.add_module("resnet_block3", resnet_block(128, 256, 2))

    net.add_module("global_avg_pool", GlobalAvgPool2d())  # GlobalAvgPool2d的输出: (Batch, 512, 1, 1)
    net.add_module("fc", nn.Sequential(FlattenLayer(), nn.Linear(256, 10)))

    # 测试网络
    X = torch.rand((1, 1, 28, 28))
    for name, layer in net.named_children():
        X = layer(X)
        print(name, ' output shape:/t', X.shape)

    # 训练
    device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
    lr, num_epochs = 0.001, 100
    optimizer = torch.optim.Adam(net.parameters(), lr=lr)
    batch_size = 1000
    net = net.to(device)

    print("training on ", device)
    loss = torch.nn.CrossEntropyLoss()
    loop_times = round(60000 / batch_size)
    train_acc_plot = []
    test_acc_plot = []
    loss_plot = []
    for epoch in range(num_epochs):
        train_l_sum, train_acc_sum, n, batch_count, start = 0.0, 0.0, 0, 0, time.time()

        for i in tqdm(range(1, loop_times)):
            x = train_images[(i - 1) * batch_size:i * batch_size]
            y = train_labels[(i - 1) * batch_size:i * batch_size]
            x = torch.unsqueeze(x, 1)  # 对齐维度
            X = x.to(device)
            y = y.to(device)
            y_hat = net(X)
            l = loss(y_hat, y)
            optimizer.zero_grad()
            l.backward()
            optimizer.step()
            train_l_sum += l.cpu().item()
            train_acc_sum += (y_hat.argmax(dim=1) == y).sum().cpu().item()
            n += y.shape[0]
            batch_count += 1
        test_acc = evaluate_accuracy(test_images, test_labels, net)
        print('epoch %d, loss %.4f, train acc %.3f, test acc %.3f, time %.1f sec'
              % (epoch + 1, train_l_sum / batch_count, train_acc_sum / n, test_acc, time.time() - start))
        torch.save(net.state_dict(), 'logs/Epoch%d-Loss%.4f-train_acc%.4f-test_acc%.4f.pth' % (
            (epoch + 1), train_l_sum / batch_count, train_acc_sum / n, test_acc))
        print("save successfully")

        test_acc_plot.append(test_acc)
        train_acc_plot.append(train_acc_sum / n)
        loss_plot.append(train_l_sum / batch_count)

    x = range(0,100)
    plt.plot(x,test_acc_plot,'r')
    plt.plot(x, train_acc_plot, 'g')
    plt.plot(x, loss_plot, 'b')
    print("*" * 50)

main_pthoto.py

# author:Hurricane
# date:  2020/11/6
# E-mail:[email protected]

import cv2 as cv
import numpy as np
import os
from Pre_treatment import get_number as g_n
import predict as pt
from time import time
from Pre_treatment import softmax
net = pt.get_net()
orig_path = r"F:\PyCharm\Practice\hand_wrtten\real_img_resize"
img_list = os.listdir(orig_path)

# img_path = r'F:\PyCharm\Practice\hand_wrtten\real_img\7.jpg'

for img_name in img_list:
    since = time()
    img_path = os.path.join(orig_path, img_name)
    img = cv.imread(img_path)
    img_bw = g_n(img)
    img_bw_c = img_bw.sum(axis=1) / 255
    img_bw_r = img_bw.sum(axis=0) / 255
    r_ind, c_ind = [], []
    for k, r in enumerate(img_bw_r):
        if r >= 5:
            r_ind.append(k)
    for k, c in enumerate(img_bw_c):
        if c >= 5:
            c_ind.append(k)
    img_bw_sg = img_bw[ c_ind[0]:c_ind[-1],r_ind[0]:r_ind[-1]]
    leng_c = len(c_ind)
    leng_r = len(r_ind)
    side_len = leng_c + 20
    add_r = int((side_len-leng_r)/2)
    img_bw_sg_bord = cv.copyMakeBorder(img_bw_sg,10,10,add_r,add_r,cv.BORDER_CONSTANT,value=[0,0,0])
    # 展示图片
    cv.imshow("img", img_bw)
    cv.imshow("img_sg", img_bw_sg_bord)
    c = cv.waitKey(1) & 0xff

    img_in = cv.resize(img_bw_sg_bord, (28, 28))
    result_org = pt.predict(img_in,  net)
    result = softmax(result_org)
    best_result = result.argmax(dim=1).item()
    best_result_num = max(max(result)).cpu().detach().numpy()
    if best_result_num <= 0.5:
        best_result = None

    # 显示结果
    img_show = cv.resize(img, (600, 600))
    end_predict = time()
    fps = np.ceil(1 / (end_predict - since))
    font = cv.FONT_HERSHEY_SIMPLEX
    cv.putText(img_show, "The number is:" + str(best_result), (1, 30), font, 1, (0, 0, 255), 2)
    cv.putText(img_show, "Probability is:" + str(best_result_num), (1, 60), font, 1, (0, 255, 0), 2)
    cv.putText(img_show, "FPS:" + str(fps), (1, 90), font, 1, (255, 0, 0), 2)
    cv.imshow("result", img_show)
    cv.waitKey(1)
    print(result)
    print("*" * 50)
    print("The number is:", best_result)

main.py

# author:Hurricane
# date:  2020/11/6
# E-mail:[email protected]

import cv2 as cv
import numpy as np
import os
from Pre_treatment import get_number as g_n
from Pre_treatment import get_roi
import predict as pt
from time import time
from Pre_treatment import softmax

# 实时检测视频
capture = cv.VideoCapture(0,cv.CAP_DSHOW)
capture.set(3, 1920)
capture.set(4, 1080)
net = pt.get_net()

# img_path = r'F:\PyCharm\Practice\hand_wrtten\real_img\7.jpg'
while (True):
    ret, frame = capture.read()
    since = time()
    if ret:
        # frame = cv.imread(img_path)

        img_bw = g_n(frame)
        img_bw_sg = get_roi(img_bw)
        # 展示图片
        cv.imshow("img", img_bw_sg)
        c = cv.waitKey(1) & 0xff
        if c == 27:
            capture.release()
            break
        img_in = cv.resize(img_bw_sg, (28, 28))
        result_org = pt.predict(img_in, net)
        result = softmax(result_org)
        best_result = result.argmax(dim=1).item()
        best_result_num = max(max(result)).cpu().detach().numpy()
        if best_result_num <= 0.5:
            best_result = None

        # 显示结果
        img_show = cv.resize(frame, (600, 600))
        end_predict = time()
        fps = round(1/(end_predict-since))
        font = cv.FONT_HERSHEY_SIMPLEX
        cv.putText(img_show, "The number is:" + str(best_result), (1, 30), font, 1, (0, 0, 255), 2)
        cv.putText(img_show, "Probability is:" + str(best_result_num), (1, 60), font, 1, (0, 255, 0), 2)
        cv.putText(img_show, "FPS:" + str(fps), (1, 90), font, 1, (255, 0, 0), 2)
        cv.imshow("result", img_show)
        cv.waitKey(1)
        print(result)
        print("*" * 50)
        print("The number is:", best_result)


    else:
        print("please check camera!")
        break

Pre_treatment.py

# author:Hurricane
# date:  2020/11/6
# E-mail:[email protected]


import cv2 as cv
import numpy as np
import os


def get_number(img):

    img_gray = cv.cvtColor(img, cv.COLOR_RGB2GRAY)
    img_gray_resize = cv.resize(img_gray, (600, 600))
    ret, img_bw = cv.threshold(img_gray_resize, 200, 255, cv.THRESH_BINARY)
    kernel = np.ones((3, 3), np.uint8)
    # img_open = cv.morphologyEx(img_bw,cv.MORPH_CLOSE,kernel)
    img_open = cv.dilate(img_bw, kernel, iterations=2)
    num_labels, labels, stats, centroids = \
        cv.connectedComponentsWithStats(img_open, connectivity=8, ltype=None)
    for sta in stats:
        if sta[4] < 1000:
            cv.rectangle(img_open, tuple(sta[0:2]), tuple(sta[0:2] + sta[2:4]), (0, 0, 255), thickness=-1)
    return img_open

def get_roi(img_bw):
    img_bw_c = img_bw.sum(axis=1) / 255
    img_bw_r = img_bw.sum(axis=0) / 255
    all_sum = img_bw_c.sum(axis=0)
    if all_sum != 0:
        r_ind, c_ind = [], []
        for k, r in enumerate(img_bw_r):
            if r >= 5:
                r_ind.append(k)
        for k, c in enumerate(img_bw_c):
            if c >= 5:
                c_ind.append(k)
        img_bw_sg = img_bw[c_ind[0]:c_ind[-1], r_ind[0]:r_ind[-1]]
        leng_c = len(c_ind)
        leng_r = len(r_ind)
        side_len = max(leng_c, leng_r) + 20
        if leng_c == side_len:
            add_r = int((side_len - leng_r) / 2)
            add_c = 10
        else:
            add_r = 10
            add_c = int((side_len - leng_c) / 2)
        img_bw_sg_bord = cv.copyMakeBorder(img_bw_sg, add_c, add_c, add_r, add_r, cv.BORDER_CONSTANT, value=[0, 0, 0])
        return img_bw_sg_bord
    else:
        return img_bw

def softmax(X):
    X_exp = X.exp()
    partition = X_exp.sum(dim=1, keepdim=True)
    return X_exp / partition

predict.py

# author:Hurricane
# date:  2020/11/5
# E-mail:[email protected]
# -------------------------------------#
#       对单张图片进行预测
# -------------------------------------#
import numpy as np
import struct
import matplotlib.pyplot as plt
import cv2 as cv
import random
import torch
from torch import nn, optim
import torch.nn.functional as F




class Residual(nn.Module):  # 本类已保存在d2lzh_pytorch包中方便以后使用
    def __init__(self, in_channels, out_channels, use_1x1conv=False, stride=1):
        super(Residual, self).__init__()
        self.conv1 = nn.Conv2d(in_channels, out_channels, kernel_size=3, padding=1, stride=stride)
        self.conv2 = nn.Conv2d(out_channels, out_channels, kernel_size=3, padding=1)
        if use_1x1conv:
            self.conv3 = nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=stride)
        else:
            self.conv3 = None
        self.bn1 = nn.BatchNorm2d(out_channels)
        self.bn2 = nn.BatchNorm2d(out_channels)

    def forward(self, X):
        Y = F.relu(self.bn1(self.conv1(X)))
        Y = self.bn2(self.conv2(Y))
        if self.conv3:
            X = self.conv3(X)
        return F.relu(Y + X)


class GlobalAvgPool2d(nn.Module):
    # 全局平均池化层可通过将池化窗口形状设置成输入的高和宽实现
    def __init__(self):
        super(GlobalAvgPool2d, self).__init__()

    def forward(self, x):
        return F.avg_pool2d(x, kernel_size=x.size()[2:])


def resnet_block(in_channels, out_channels, num_residuals, first_block=False):
    # num_residuals:残差数
    if first_block:
        assert in_channels == out_channels  # 第一个模块的通道数同输入通道数一致
    blk = []
    for i in range(num_residuals):
        if i == 0 and not first_block:
            blk.append(Residual(in_channels, out_channels, use_1x1conv=True, stride=2))
        else:
            blk.append(Residual(out_channels, out_channels))
    return nn.Sequential(*blk)

class FlattenLayer(torch.nn.Module):
    def __init__(self):
        super(FlattenLayer, self).__init__()
    def forward(self, x): # x shape: (batch, *, *, ...)
        return x.view(x.shape[0], -1)
def get_net():
    # 构建网络
    # ResNet模型
    model_path = r"F:\PyCharm\Practice\hand_wrtten\logs\Epoch100-Loss0.0000-train_acc1.0000-test_acc0.9930.pth"
    device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
    net = nn.Sequential(
        nn.Conv2d(1, 64, kernel_size=7, stride=2, padding=3),
        nn.BatchNorm2d(64),
        nn.ReLU(),
        nn.MaxPool2d(kernel_size=3, stride=2, padding=1))

    net.add_module("resnet_block1", resnet_block(64, 64, 2, first_block=True))
    net.add_module("resnet_block2", resnet_block(64, 128, 2))
    net.add_module("resnet_block3", resnet_block(128, 256, 2))

    net.add_module("global_avg_pool", GlobalAvgPool2d())  # GlobalAvgPool2d的输出: (Batch, 512, 1, 1)
    net.add_module("fc", nn.Sequential(FlattenLayer(), nn.Linear(256, 10)))

    # 测试网络
    # X = torch.rand((1, 1, 28, 28))
    # for name, layer in net.named_children():
    #     X = layer(X)
    #     print(name, ' output shape:\t', X.shape)

    # 加载网络模型
    print("Load weight into state dict...")
    stat_dict = torch.load(model_path, map_location=device)
    net.load_state_dict(stat_dict)
    net.to(device)
    net.eval()
    print("Load finish!")
    return net


def predict(img, net):
    device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')

    img_in = torch.from_numpy(img)
    img_in = torch.unsqueeze(img_in, 0)
    img_in = torch.unsqueeze(img_in, 0).to(device)
    img_in = img_in.float()
    result_org = net(img_in)
    return result_org



7.结束语

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