: 训练集第 i 个向量中的第 j 个元素(第 i 行第 j 列): 训练集第 i 个向量(第 i 行): 总共 m 行 : 总共 n 列 适应这些多特征的假设函数的多变量形式如下: 使用矩阵乘法的定义,我们的多变量假设函数可以简洁地表示为: 其中 二. Gradient Descent for Multiple Variables 多个变量的梯度下降,同时更新...
因此公式可以简化为: ℎ𝜃(𝑥) = 𝜃𝑇𝑋,其中上标𝑇代表矩阵转置。 4.2 多变量梯度下降(Gradient Descent for Multiple Variables) 与单变量线性回归类似,在多变量线性回归中,我们也构建一个代价函数,则这个代价函数是所有建模误差的平方和,即: 其中: ℎ𝜃(𝑥) = 𝜃𝑇𝑋 = 𝜃0 + 𝜃...
withopen(filename,'r') as f: forlineinf.readlines(): line=line.split(',') current=[int(item)foriteminline] #5.5277,9.1302 data.append(current) returndata data=load_exdata('ex1data2.txt'); data=np.array(data,np.int64) x=data[:,(0,1)].reshape((-1,2)) y=data[:,2].reshape(...
defload_exdata(filename):data=[]withopen(filename,'r')asf:forlineinf.readlines():line=line.split(',')current=[int(item)foriteminline]#5.5277,9.1302data.append(current)returndata data=load_exdata('ex1data2.txt');data=np.array(data,np.int64)x=data[:,(0,1)].reshape((-1,2))y=dat...
Python allows you to assign values to multiple variables in one line:ExampleGet your own Python Server x, y, z = "Orange", "Banana", "Cherry"print(x)print(y)print(z) Try it Yourself » Note: Make sure the number of variables matches the number of values, or else you will get ...
# Multiple variables multiple_variable = lambda a, b, c: a ** 2 - 3 * b + 4 * c print(multiple_variable(5, 5, 3)) # 22 另一个函数中的 Lambda 函数 在另一个函数中使用 lambda 函数。 def power(x): return lambda n : x ** n ...
Creating Variables (创建变量) Python has no command for declaring a variable. 与其他编程语言不同,Python 没有声明变量的命令。 A variable is created the moment you first assign a value to it. 首次为其赋值时,才会创建变量。 x = 5 y = "John" ...
for i in range(X.shape[2]): Xmin[0,i] = np.min(X[:,0,i]) Xmax[0,i] = np.max(X[:,0,i]) return (X - Xmin) / (Xmax - Xmin) # 0均值标准化 def zero_mean_normalization(X): mu = np.zeros((1, X.shape[2])) sigma = np.zeros((1, X.shape[2])) for i in ra...
Creating Variables (创建变量) Python has no command for declaring a variable. 与其他编程语言不同,Python 没有声明变量的命令。 A variable is created the moment you first assign a value to it. 首次为其赋值时,才会创建变量。 --- 代码块分割线 --- x = ...
sequence type that contains 0 or more data items. Tuples are fixed after they are generated, and no data items in them can be replaced or deleted. Tuple types are useful for expressing fixed data items, multiple return values for two numbers, simultaneous assignment of multiple variables, and...