一 什么是机器学习(Machine Learning)
- Arthur Samuel
The field of study that gives computers the ability to learn without being explicitly programmed.
在没有明确设置的情况下让计算机获得学习的能力
- Tom Mitchell
A computer program is said to learn from experience E with respect to some class of tasks T and performance measure P, if its performance at tasks in T, as measured by P, improves with experience E.
二 Machine learning algorithms
Supervised learning
In supervised learning, we are given a data set and already know what our correct output should look like, having the idea that there is a relationship between the input and the output.
| 两类 | 回归regression | 分类classification |
|---|---|---|
| 预测 | 连续输出 | 离散输出 |
| 变量映射 | 连续函数 | 离散分类 |
| 例子 | 估算房子售价 | 判断肿瘤良性恶性 |
Unsupervised learning
Unsupervised learning, allows us to approach problems with little or no idea what our results should look like. We can derive structure from data where we don’t necessarily know the effect of the variables.
对数据进行聚类(clustering)来提取数据的结构
examples
- Market segmentation(市场分析)
- Social network analysis(社交网络分析)
- 新闻分类
编程环境推荐
Octave
优越性：一行代码解决鸡尾酒会问题
