我的Xtrain数据具有3个功能。请帮我提供此代码 代码如下：

from matplotlib.colors import ListedColormap
X_set,y_set = X_train,y_train
X1,X2 = np.meshgrid(np.arange(start = X_set[:,0].min() - 1,stop = X_set[:,0].max() + 1,step = 0.01),np.arange(start = X_set[:,1].min() - 1,1].max() + 1,step = 0.01))
plt.contourf(X1,X2,classifier.predict(np.array([X1.ravel(),X2.ravel()]).T).reshape(X1.shape),alpha = 0.75,cmap = ListedColormap(('red','green')))
plt.xlim(X1.min(),X1.max())
plt.ylim(X2.min(),X2.max())
for i,j in enumerate(np.unique(y_set)):
`plt.scatter(X_set[y_set == j,0],X_set[y_set == j,1],c = ListedColormap(('red','green'))(i),label = j)`
plt.title('K-NN (Training set)')
plt.xlabel('Age')
plt.ylabel('Estimated Salary')
plt.legend()
plt.show()