classifier报错
--------------------------------------------------------------------------- NameError Traceback (most recent call last) <ipython-input-27-09489cf34698> in <module>() ----> 1 plot_decision_regions(X, y, resolution=0.02) <ipython-input-26-4a04ed7daaaa> in plot_decision_regions(X, y, resolution) 11 np.arange(x2_min, x2_max, resolution)) 12 ---> 13 z = classifier.predict(np.array([xx1.ravel(), xx2.ravel()]).T) 14 print(xx1.ravel()) 15 print(xx2.ravel())NameError: name 'classifier' is not defined