MNIST数据集是一个手写体数据集，这个数据集由四部分组成，分别是一个训练图片集，一个训练标签集，一个测试图片集，一个测试标签集；我们可以看出这个其实并不是普通的文本文件或是图片文件，而是一个压缩文件，下载并解压出来，我们看到的是二进制文件。其中包含60000张手写体识别数字图片。(MNIST data set is a handwritten data set, which consists of four parts: a training picture set, a training label set, a test picture set and a test label set. We can see that this data set is not a normal text file or picture file, but a compressed file, download and decompress it. What we see is binary text. Pieces.It contains 60,000 handwritten recognition digital pictures.)