多变量线性回归练习

读取数据+特征归一化

mean是均值

将特征大小控制在 -1~1之间

房屋的面积对价格的影响

卧室数量对价格的影响

损失函数

def costFunction(X,y,theta):
inner =np.power(X@theta-y,2)
return np.sum(inner)/(2*len(X))

梯度下降

def gradientDescent(X,y,theta,alpha,iters):
    costs = []
    
    for i in range(iters):
        theta = theta - (X.T @ (X@theta - y) ) * alpha / len(X)
        cost = costFunction(X,y,theta)
        costs.append(cost)
        
        if i % 100 == 0:
            print(cost)
            
    return theta,costs
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