from?matplotlib.colors?import?ListedColormap

def?ploy_decision_regions(X,?y,?classifier,?resolution?=?0.02):
????markers?=?('s',?'x',?'o',?'v')
????colors?=?('red',?'blue',?'lightgreen',?'gray',?'cyan')
????cmap?=?ListedColormap(colors[:len(np.unique(y))])
????x1_min,?x1_max?=?X[:,0].min()?-?1,?X[:,?0].max()
????x2_min,?x2_max?=?X[:,1].min()?-?1,?X[:,?1].max()
????
????xx1,?xx2?=?np.meshgrid(np.arange(x1_min,?x1_max,?resolution),?np.arange(x2_min,?x2_max,?resolution))
????Z?=?classifier.predict(np.array([xx1.ravel(),?xx2.ravel()]).T).reshape(xx1.shape)
????
????plt.contourf(xx1,?xx2,?Z,?alpha=0.4,?cmap=cmap)
????plt.xlim(xx1.min(),?xx1.max())
????plt.ylim(xx2.min(),?xx2.max())
????
????for?idx,?cl?in?enumerate(np.unique(y)):
????????plt.scatter(x=X[y==cl,?0],?y=X[y==cl,?1],?alpha=0.8,?c=cmap(idx),?marker=markers[idx],?label=cl)