分类图绘制

    plt.figure(facecolor = 'w')
    #面板分成3类
    cm_light = mpl.colors.ListedColormap(['#77E0A0', '#FF8080', '#A0A0FF'])
    #根据y的不同，填充颜色也不同
    plt.pcolormesh(x1, x2, y_hat, cmap=cm_light)

    plt.scatter(x[:, 0], x[:, 1], c='y')
    patchs = [mpatches.Patch(color='#77E0A0', label = 'Iris-setosa'),
              mpatches.Patch(color='#FF8080', label = 'Itis-versicolor'),
              mpatches.Patch(color = '#A0A0FF', label = 'Iris-virginica')]
    plt.legend(handles=patchs, fancybox = True, framealpha=0.8)
    plt.show()