1.What is machine learning?
Machine learning is the field of study that gives computers the ability to learn
without being explicitly programmed.
A computer program is said to learn from experience E with respect to some task T and some performance measure
P if its performance on T, as measured by P, improves with experience E.
2.Differences
betweent
classification and regression problem
Classification
is appropriate when we are trying to predict one of a small number ofdiscrete-valued
outputs, such as whether it will rain (which we might designate as class 0), or not (say class 1). (少量离散值)
Regression is appropriate when we are trying to predict a continuous-valued output. Even though the number of shares
traded is technically discrete-valued (i.e., an integer), it would be more natural to treat it as a continuous value (similar to the housing prices example in the lecture).(大量离散值,连续值)
2.Differences
betweent Supervised Learning and Unsupervised Learning
Supervised learning "right answers" given. eg:对于房价预测问题,数据中的每个数据,每个面积的房价已给出,预测更多房价。
训练集中的每个数据都有正确答案。算法基于那些数据做出判断。
无监督学习(unsupervised
learning):设计分类器时候,用于处理未被分类标记的样本集