初学机器学习：分类问题-感知机算法

https://nbviewer.jupyter.org/github/bingozhu88/MachineLearning/blob/master/%E7%AC%AC%E4%BA%8C%E8%AE%B2-%E5%88%86%E7%B1%BB%E9%97%AE%E9%A2%98/%E4%BB%A3%E7%A0%81%E5%B1%95%E7%A4%BA.ipynb