Machine Learning Week_1 Welcome

目录

• 0 Welcome
  • 0.1 Video: Welcome to Machine Learning!
    • Transcript
    • unfamiliar words
  • 0.2 Reading: Machine Learning Honor Code
    • Guidelines for Posting Code in Discussion Forums
    • unfamiliar words

0 Welcome

0.1 Video: Welcome to Machine Learning!

Transcript

What is machine learning? You probably use it dozens of times a day without even knowing it.

Each time you do a web search on Google or Bing, that works so well because their machine learning software has figured out how to rank what pages. When Facebook or Apple's photo application recognizes your friends in your pictures, that's also machine learning.

Each time you read your email and a spam filter saves you from having to wade through tons of spam, again, that's because your computer has learned to distinguish spam from non-spam email.

So, that's machine learning.

There's a science of getting computers to learn without being explicitly programmed.

One of the research projects that I'm working on is getting robots to tidy up the house. How do you go about doing that? Well what you can do is have the robot watch you demonstrate the task and learn from that. The robot can then watch what objects you pick up and where to put them and try to do the same thing even when you aren't there.

For me, one of the reasons I'm excited about this is the AI, or artificial intelligence problem. Building truly intelligent machines, we can do just about anything that you or I can do. Many scientists think the best way to

make progress on this is through learning algorithms called neural networks, which mimic how the human brain works, and I'll teach you about that, too.

In this class, you learn about machine learning and get to implement them yourself. I hope you sign up on our website and join us.

unfamiliar words

explicit [ɪkˈsplɪsɪt]

1. ADJ Something that is explicit is expressed or shown clearly and openly, without any attempt to hide anything.

explicitly [ɪkˈsplɪsɪtli]

demonstrate [ˈdemənstreɪt]

1. V-T To demonstrate a fact means to make it clear to people.

2. V-T If you demonstrate something, you show people how it works or how to do it.
   
   eg. A selection of cosmetic companies will be there to demonstrate their new products

mimic [ˈmɪmɪk]

1. V-T If someone or something mimics another person or thing, they try to be like them.
   
   eg. The computer doesn't mimic human thought; it reaches the same ends by different means.

implement [ˈɪmplɪment]

1. V-T to make sth that has been officially decided start to happen or be used

   • to implement changes/decisions/policies/reforms(改革)

2. N-COUNT An implement is a tool or other piece of equipment.
   
   eg. writing implements

0.2 Reading: Machine Learning Honor Code

We strongly encourage students to form study groups, and discuss the lecture videos (including in-video questions). We also encourage you to get together with friends to watch the videos together as a group. However, the answers that you submit for the review questions should be your own work. For the programming exercises, you are welcome to discuss them with other students, discuss specific algorithms, properties of algorithms, etc.;

We ask only that you not look at any source code written by a different student, nor show your solution code to other students.

Guidelines for Posting Code in Discussion Forums

Scenario 1: Code to delete

Learner Question/Comment: "Here is the code I have so far, but it fails the grader. Please help me fix it."

Why Delete?: The reason is that if there is a simple fix provided by a student, a quick copy and paste with a small edit will provide credit without individual effort.

Learner Question: A student substitutes words for the math operators, but includes the variable names (or substitutes the equivalent greek letters (θ for 'theta', etc). This student also provides a sentence-by-sentence, line by line, description of exactly what their code implements. "The first line of my script has the equation "hypothesis equals theta times X", but I get the following error message...".

Why Delete?: This should be deleted. “Spelling out” the code in English is the same as using the regular code.

Scenario 2: Code not to delete

Learner Question: How do I subset a matrix to eliminate the intercept?

Mentor Response: This probably would be okay, especially if the person posting makes an effort to not use familiar variable names, or to use a context which has nothing to do with the contexts in the assignments.

It is clearly ok to show examples of Octave code to demonstrate a technique. Even if the technique itself is directly applicable to a programming problem at hand. As long as what is typed cannot be "cut and pasted" into the program at hand.

E.g. how do I set column 1 of a matrix to zero? Try this in your Octave work area:

>> A = magic(3)

>> A(:,1) = 0

The above is always acceptable (in my understanding). Demonstrating techniques and learning the language/syntax are important Forum activities.

unfamiliar words

Forum [ˈfɔːrəm]

1. N-COUNT A forum is a place, situation, or group in which people exchange ideas and discuss issues, especially important public issues.

lecture [ˈlektʃər]

1. N-COUNT A lecture is a talk someone gives in order to teach people about a particular subject, usually at a university or college.

property [ˈprɒpəti] properties ['prɒpətɪz]

1. N-UNCOUNT Someone's property is all the things that belong to them or something that belongs to them.
   
   eg. Richard could easily destroy her personal property to punish her for walking out on him.

2. N-COUNT The properties of a substance or object are the ways in which it behaves in particular conditions.
   
   eg. A radio signal has both electrical and magnetic properties.

Scenario [səˈnærioʊ]

1. N-COUNT If you talk about a likely or possible scenario, you are talking about the way in which a situation may develop.
   
   eg. Let me suggest a possible scenario.

provide credit

1. N-COUNT Recognition by a college or university that a course of studies has been successfully completed; typically measured in semester hours. At universities and colleges you need a certain number of credits to be awarded a degree.

substitute [ˈsʌbstɪtjuːt] substitutes [ˈsʌbstɪtjuːts]

1. N-COUNT A substitute is something that you have or use instead of something else.
   
   eg. She is seeking a substitute for the very man whose departure made her cry.

equivalent [ɪˈkwɪvələnt] greek letters

1. N-SING If one amount or value is the equivalent of another, they are the same.

regular code.

1. ADJ Regular is used to mean "normal.
   
   eg. The product looks and burns like a regular cigarette.

2. ADJ Regular events have equal amounts of time between them, so that they happen, for example, at the same time each day or each week.
   
   eg. Get regular exercise.

subset [ˈsʌbset]

1. N-COUNT A subset of a group of things is a smaller number of things that belong together within that group.

terminate [ˈtɜːmɪneɪt]

1. V-T/V-I When you terminate something or when it terminates, it ends completely.
   
   eg. Her next remark abruptly terminated the conversation.

eliminate [ɪˈlɪmɪneɪt]

1. V-T To eliminate something, especially something you do not want or need, means to remove it completely.

intercept [ˌɪntərˈsept] 截距[mathematical]，拦截

1. V-T If you intercept someone or something that is travelling from one place to another, you stop them before they get to their destination.