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29、实现逻辑回归算法与决策边界可视化
逻辑回归的theta有没有什么几何意义?
引入分类问题非常重要的概念:决策边界- def plot_decision_boundary(model, axis):
- # axis代表:x轴y轴的范围
- x0, x1 = np.meshgrid(
- np.linspace(axis[0], axis[1], int((axis[1]-axis[0])*100)).reshape(-1, 1),
- np.linspace(axis[2], axis[3], int((axis[3]-axis[2])*100)).reshape(-1, 1),
- )
- X_new = np.c_[x0.ravel(), x1.ravel()]
- y_predict = model.predict(X_new)
- zz = y_predict.reshape(x0.shape)
- from matplotlib.colors import ListedColormap
- custom_cmap = ListedColormap(['#EF9A9A','#FFF59D','#90CAF9'])
- plt.contourf(x0, x1, zz, linewidth=5, cmap=custom_cmap)
复制代码- plot_decision_boundary(log_reg, axis=[4, 10, 1, 5])
- plt.scatter(X[y==0,0], X[y==0,1])
- plt.scatter(X[y==1,0], X[y==1,1])
- plt.scatter(X[y==2,0], X[y==2,1])
- plt.show()
复制代码
ipynb文件在附件,可提供下载!
视频教程请参考:http://www.ai111.vip/thread-349-1-1.html
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