Py 波士顿房价问题

from sklearn.linear_model import LinearRegression
from sklearn.datasets import load_boston
from sklearn.model_selection import train_test_split

boston = load_boston()
X = boston['data']
y = boston['target']

X_train,X_test,y_train,y_test=train_test_split(X,y,test_size=0.2,random_state=42)
clf=LinearRegression().fit(X_train,y_train)

y_pred = clf.predict(X_test)

import matplotlib.pyplot as plt

plt.figure(figsize=(10,6))
plt.plot(range(y_pred.shape[0]),y_pred,c='b',lw=1.5,ls='-')
plt.plot(range(y_test.shape[0]),y_test,c='r',lw=1.5,ls='-')
plt.savefig('boston.png')
plt.show