说明：  使用鸢尾花数据集，预测鸢尾花种类。并随机选取100个样本作为训练数据，剩下50个作为测试数据。设置输入层四个神经元，接收输入的四个向量数据。设置一层隐含层，使用sigmoi激活函数，此问题为三分类问题，输出层激活函数使用sigmoi函数，神经元个数设置为3个，本类别输出1，其余类别输出0。
(Iris, using data sets to predict Iris species. 100 samples were randomly selected as training data, and the remaining 50 samples were used as test data. Four neurons in the input layer are set to receive the four vector data. Set a hidden layer and use the sigmoi activation function. This problem is a three classification problem. The output layer activation function uses the sigmoi function. The number of neurons is set to 3. This category outputs 1 and the other categories output 0.)