ver0.83--readMNIST.m

%关于MNIST手写图像数据库的读取。%输入：%id - 图像的28x28大小单元格数组；%n - 要处理的图像数；%labels - 对应于图像的标签单元格数组；%rand_on - 参数，定义是否需要随机选取一对图像/标签%输出：% I - 训练图像的28x28大小单元阵列%labels - 训练集的标签矢量（真实数字）%I_test - 测试图像的28x28大小单元格数组%labels_test - 测试集的标签向量（真实数字）function [I,labels,I_test,labels_test] = readMNIST(num)％检查我们是否有MNIST数据集path = './MNIST/train-images.idx3-ubyte';if(~exist(path,'file'))    error('Training set of MNIST not found. Please download it from http://yann.lecun.com/exdb/mnist/ and put to ./MNIST folder');endfid = fopen(path,'r','b');  %big-endianmagicNum = fread(fid,1,'int32');    % “fread”以二进制形式，从文件读出数据。if(magicNum~=2051)     display('Error: cant find magic number');    return;endimgNum = fread(fid,1,'int32');  %Number of imagesrowSz = fread(fid,1,'int32');   %Image heightcolSz = fread(fid,1,'int32');   %Image widthif(num<imgNum)     imgNum=num; endfor k=1:imgNum    I{k} = uint8(fread(fid,[rowSz colSz],'uchar'));%[M,N]：读出N个数据，构成列向量，填入M*N矩阵endfclose(fid);%============Loading labelspath = './MNIST/train-labels.idx1-ubyte';if(~exist(path,'file'))    error('Training labels of MNIST not found. Please download it from http://yann.lecun.com/exdb/mnist/ and put to ./MNIST folder');endfid = fopen(path,'r','b');  %big-endianmagicNum = fread(fid,1,'int32');    %Magic numberif(magicNum~=2049)     display('Error: cant find magic number');    return;enditmNum = fread(fid,1,'int32');  %Number of labelsif(num<itmNum)     itmNum=num; endlabels = uint8(fread(fid,itmNum,'uint8'));   %Load all labelsfclose(fid);%============All the same for test setpath = './MNIST/t10k-images.idx';if(~exist(path,'file'))    error('Test images of MNIST not found. Please download it from http://yann.lecun.com/exdb/mnist/ and put to ./MNIST folder');endfid = fopen(path,'r','b');  magicNum = fread(fid,1,'int32');    if(magicNum~=2051)     display('Error: cant find magic number');    return;endimgNum = fread(fid,1,'int32');  rowSz = fread(fid,1,'int32');   colSz = fread(fid,1,'int32');   if(num<imgNum)     imgNum=num; endfor k=1:imgNum    I_test{k} = uint8(fread(fid,[rowSz colSz],'uchar'));endfclose(fid);%============Test labelspath = './MNIST/t10k-labels.idx1-ubyte';if(~exist(path,'file'))    error('Test labels of MNIST not found. Please download it from http://yann.lecun.com/exdb/mnist/ and put to ./MNIST folder');endfid = fopen(path,'r','b');  magicNum = fread(fid,1,'int32');    if(magicNum~=2049)     display('Error: cant find magic number');    return;enditmNum = fread(fid,1,'int32');  if(num<itmNum)     itmNum=num; endlabels_test = uint8(fread(fid,itmNum,'uint8'));   fclose(fid);

如果输入为1000，就是1000张用于训练，1000张用于测试？？