实战：使用岭回归模型

完整代码：

import numpy as np
import matplotlib.pyplot as plt
from sklearn.linear_model import LinearRegression
from sklearn.datasets import make_regression
from sklearn.model_selection import train_test_split
from sklearn.sklearn.datasets import load_diabetesX, y = make_regression(n_samples=100, n_features=2, n_informative=2, noise=50, random_state=1)
X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=8)lr = LinearRegression().fit(X_train, y_train)
print(f"y = {lr.coef_[0]:.3f}X1 + {lr.coef_[1]:.3f}X2 + {lr.intercept_:.3f}")
print(f"score = {lr.score(X_test, y_test)}")

输出：

y = 11.512X1 + -282.514X2 + 152.563
score = 0.4593422174874441

调整岭回归的系数

完整代码：

import numpy as np
import matplotlib.pyplot as plt
from sklearn.linear_model import Ridge
from sklearn.datasets import make_regression
from sklearn.model_selection import train_test_split
from sklearn.datasets import load_diabetesdata = load_diabetes()
X, y = data.data, data.target
X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=8)lr = Ridge(alpha=0.1).fit(X_train, y_train)
print(f"y = {lr.coef_[0]:.3f}x1 + {lr.coef_[1]:.3f}x2 + {lr.intercept_:.3f}")
print(f"score = {lr.score(X_test, y_test)}")

输出：

y = 24.780x1 + -228.334x2 + 152.481
score = 0.4734012479881621

绘制学习曲线

完整代码：

import numpy as np
import matplotlib.pyplot as plt
from sklearn.linear_model import Ridge, LinearRegression
from sklearn.datasets import make_regression
from sklearn.model_selection import train_test_split
from sklearn.datasets import load_diabetes
from sklearn.model_selection import learning_curve, KFolddef plot_learning_curve(est, X, y):# 将数据拆分20次用来对模型进行评分training_set_size, train_scores, test_scores = learning_curve(est,X,y,train_sizes=np.linspace(.1, 1, 20),cv=KFold(20, shuffle=True, random_state=1))# 获取模型名称estimator_name = est.__class__.__name__# 绘制模型评分line = plt.plot(training_set_size, train_scores.mean(axis=1), "--", label="training " + estimator_name)plt.plot(training_set_size, test_scores.mean(axis=1), "-", label="test " + estimator_name, c=line[0].get_color())plt.xlabel("Training set size")plt.ylabel("Score")plt.ylim(0, 1.1)# 加载数据
data = load_diabetes()
X, y = data.data, data.target# 绘制图形
plot_learning_curve(Ridge(alpha=1), X, y)
plot_learning_curve(LinearRegression(), X, y)
plt.legend(loc=(0, 1.05), ncol=2, fontsize=11)
plt.show()

输出结果如下：