梯度下降算法python实现
2021/11/14 9:09:49
本文主要是介绍梯度下降算法python实现,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
def fun(x, y, w, b): l = 0 for i in range(4): l += (y[i] - (b + w * x[i]))**2 # l = sum(y - (b + w * x)**2 for x, y in zip(x, y)) / 8 return l / 8 # 梯度下降法 def gradient_descent(): times = 100 # 迭代次数 alpha = 0.001 # 步长 w = 0 # w的初始值 b = 0 # b的初始值 x = [0.0, 1.0, 2.0, 3.0] y = [3.1, 4.9, 7.2, 8.9] # 梯度下降算法 for i in range(times): w = w - alpha / 4 * sum([x * ((b + w * x) - y) for x, y in zip(x, y)]) b = b - alpha / 4 * sum([(b + w * x) - y for x, y in zip(x, y)]) l = fun(x, y, w, b) print("第%d次迭代:w=%f,b=%f,l=%f" % (i + 1, w, b, l)) if __name__ == "__main__": gradient_descent()
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