练习:Planar data classification with a hidden layer
b2=np.zeros((1,1))#用于输出1*1维的全部值是0的矩阵W2=np.random.randn(4,4)#生成随机4*4的矩阵,取值为正太分布随机样本predictions=np.where(A2>0.5,1,0)everytimeIintendtoapplyaif/elseactionwithtwopossibleoutcomesintoadatastructure(i.e.int