一、获取SVNH数据

数据集集地址-http://ufldl.stanford.edu/housenumbers/

提供两种格式的数据：

1.Format 1，图像形式，压缩包

2.Format 2， .mat格式的数据

·10 classes, 1 for each digit. Digit '1' has label 1, '9' has label 9 and '0' has label 10.

·73257 digits for training, 26032 digits for testing, and 531131 additional, somewhat less difficult samples, to use as extra training data

·Comes in two formats:

1. Original images with character level bounding boxes.

2. MNIST-like 32-by-32 images centered around a single character (many of the images do contain some distractors at the sides).

二、将.mat形式数据转换为'.png'图像

图像分别存在1-10命名的10个文件夹中，并以原始的序号命名

注：这步的操作主要是为了方便后续dataset.ImageFolder处理，其要求数据存储的文件路径格式为

├── svhn

├── trainset

│ ├── subfolders for 1 ~ 10

├── testset

具体转换的matlab代码如下：

%将SVHN数据的.mat形式转换为图像并分别存在trainset和testset文件夹下
%这两个文件夹中分别包含1-10命名的10个文件夹，其中存图像
clear;clc;
%1.创建trainset和testset文件夹
train_filename = 'trainset';
if exist(train_filename)==0 %该文件夹不存在，则直接创建
    mkdir(train_filename);
end
test_filename = 'trainset';
if exist(test_filename)==0 %该文件夹不存在，则直接创建
    mkdir(test_filename);
end
% mkdir('trainset');
% mkdir('testset');

%2.分别在trainset和testset文件夹下创建1-10命名的文件夹，用于存图
load train_32x32.mat;
labels = unique(y);
savepath = './trainset';
fileNums = length(labels);
makefile(fileNums, savepath);

savepath = './testset';
makefile(fileNums, savepath);

% 3.分别在对应标签的文件夹下存图
% for traindata
load train_32x32.mat;
savepath = './trainset/';
img_num = length(y);%size(X,4);
for i = 1:img_num
    img = X(:,:,:,i);
    imshow(img);
    n = y(i);
    choosensaveimg(img,n,i,savepath);
end

% for testdata
load test_32x32.mat;
savepath = './testset/';
img_num = length(y);%size(X,4);
for i = 1:img_num
    img = X(:,:,:,i);
    imshow(img);
    n = y(i);
    choosensaveimg(img,n,i,savepath);
end


% fun2：在文件1-10保存图片
function choosensaveimg(img,n,i,savepath)
switch n
    case 1
        imwrite(img,strcat(savepath,'1/',num2str(i),'.png'));
    case 2
        imwrite(img,strcat(savepath,'2/',num2str(i),'.png'));%该数据集本身是.png.mnist是'.jpg'
    case 3
        imwrite(img,strcat(savepath,'3/',num2str(i),'.png'));
    case 4
        imwrite(img,strcat(savepath,'4/',num2str(i),'.png'));
    case 5
        imwrite(img,strcat(savepath,'5/',num2str(i),'.png'));
    case 6
        imwrite(img,strcat(savepath,'6/',num2str(i),'.png'));
    case 7
        imwrite(img,strcat(savepath,'7/',num2str(i),'.png'));
    case 8
        imwrite(img,strcat(savepath,'8/',num2str(i),'.png'));
    case 9
        imwrite(img,strcat(savepath,'9/',num2str(i),'.png'));
    case 10
        imwrite(img,strcat(savepath,'10/',num2str(i),'.png'));
end
end

% fun1：创建1-10的文件夹
function makefile(fileNums, savepath)
for i=1:fileNums
    file_name = sprintf('%s',num2str(i));
    file_path_name_ = strcat(savepath,'/',file_name,'');
    if exist(file_path_name_)==0 %该文件夹不存在，则直接创建
        mkdir(file_path_name_);
    else %该文件夹存在，则先删除再创建
        rmdir(file_path_name_, 's'); %该文件夹中有没有文件均可
        mkdir(file_path_name_);
    end
end
end