返回到 Mathematics for Machine Learning: PCA

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This intermediate-level course introduces the mathematical foundations to derive Principal Component Analysis (PCA), a fundamental dimensionality reduction technique. We'll cover some basic statistics of data sets, such as mean values and variances, we'll compute distances and angles between vectors using inner products and derive orthogonal projections of data onto lower-dimensional subspaces. Using all these tools, we'll then derive PCA as a method that minimizes the average squared reconstruction error between data points and their reconstruction.
At the end of this course, you'll be familiar with important mathematical concepts and you can implement PCA all by yourself. If you’re struggling, you'll find a set of jupyter notebooks that will allow you to explore properties of the techniques and walk you through what you need to do to get on track. If you are already an expert, this course may refresh some of your knowledge.
The lectures, examples and exercises require:
1. Some ability of abstract thinking
2. Good background in linear algebra (e.g., matrix and vector algebra, linear independence, basis)
3. Basic background in multivariate calculus (e.g., partial derivatives, basic optimization)
4. Basic knowledge in python programming and numpy
Disclaimer: This course is substantially more abstract and requires more programming than the other two courses of the specialization. However, this type of abstract thinking, algebraic manipulation and programming is necessary if you want to understand and develop machine learning algorithms....

Jul 17, 2018

This is one hell of an inspiring course that demystified the difficult concepts and math behind PCA. Excellent instructors in imparting the these knowledge with easy-to-understand illustrations.

Jun 19, 2020

Relatively tougher than previous two courses in the specialization. I'd suggest giving more time and being patient in pursuit of completing this course and understanding the concepts involved.

筛选依据：

创建者 Vignesh N M

•Sep 12, 2018

Explaination of many things are skipped, assumption was made by the instructor that lot of things were already known by the learner. It could have been much better.

创建者 Maksim S

•Mar 25, 2020

The difficulty of the course is inadequate and the pace is not balanced. Requires a lot of search for additional resources to understand materials. I cancelled.

创建者 Kovendhan V

•Jul 11, 2020

After first two amazing courses in this specialisation, third course was a huge let down. One skill I learnt from this last course is patience.

创建者 Martin H

•Dec 08, 2019

Lack of examples to clarify abstract concepts. Big contrast in quality compared to the other courses in this specialization.

创建者 Dipto H

•Aug 07, 2020

Poor explanation by the instructor. Previous ones were very helpful. I didn't understand many topics well

创建者 Xiao L

•Jun 03, 2019

very wired assignment, a lot of error in template code. The concept is not clear.

创建者 Sai M B

•Aug 03, 2020

The lectures were not clear. I had to use other sources to understand lectures.

创建者 Pawan K S

•Jun 20, 2020

This course was the hardest I encountered in this specialisation.

创建者 Kirill T

•Jul 26, 2020

Way worse than the previous courses. Lacks explanations

创建者 Desikan S

•Sep 24, 2019

Need to improve the content and delivery of content.

创建者 Mohammed A A

•Jul 19, 2020

the course is too shallow with difficult code exame

创建者 Scoodood

•Jul 28, 2018

Video lecture not as intuitive as previous courses.

创建者 Michael B

•Nov 21, 2019

Programming assignments not well explained

创建者 youssef s a s

•Jul 27, 2020

very poor explanation of things

创建者 Salah E

•Aug 04, 2020

again too hard

创建者 ABHI G

•Aug 22, 2018

not so good

:(

创建者 Pradeep K

•Apr 30, 2020

Very Poor course on PCA, My recommendation. Don't watch it, Please don't waste your money on it.

Reasons:

1) The course on algebra and calculus was intuitive geometrically and well taught. Here the instructor bothered only doing derivations. No intuition based thinking, no analogy to real world. Just plain hard notations.

2) I don't think even the instructor would understand what was taught in the course. The excercises were completely unrelated to what was taught. Not much given examples. The examples choosen uses values like 0,1,2. Why can't you pick some odd numbers to make it bit more non confusion and clear.

3) At the end there was a review / Survey for every course. The review for this course is disabled. Clearly everyone knows how bad this is. Remove this course or make it better that is what the recommendation. There is no provision for zero stars, Had there one I would not given that also.

Really frustrated with the PCA course. Please don't waste your time and money . Get Gilbert Strang's book. That will do justice for every penny. I was able to complete the course, All thanks to Gilbert's book on Linear Algebra. Thanks

创建者 Ivan F G

•Jul 01, 2020

The technical issues with Jupyter Notebooks really made me waste too many days, a lot of my time not learning but just fighting a poorly implemented exercise. And the technical issues did not help the teacher, the notebooks had a role to give us a place to learn new concepts that he mentioned in the fly, but there were no small sets of data to test the functions. I wasn't very patient with the way he will say things like "this is the formula from the previous video", and show a different formula from what he had on the previous video. Really? Why making things obscure on purpose? You can just have said, we had our previous formula and them used properties of the transpose of a product to get this other formula. Please make an effort to redo the notebooks. Even better, do some of the examples in Phyton during class for what you do in paper, and then let us take those examples and make a general function on the notebooks. Give smaller databases, something easy to plot and test, without waiting 20+minutes to have a result.

创建者 Alistair K

•May 16, 2020

The instructor is extremely dry and monosyllabic and does a very poor job of explaining topics, he frequently introduces topics by jumping straight into formulas without bothering to explain the topic or the use of the subject he is supposed to be explaining.

The majority of lectures are no more that the lecturer reading our a formula parrot-fashion onto the screen, he makes no effort to make the subject informative or explain what is going on. In many cases, he doesn't even bother creating a lecture, he simply posts a link to Wikipedia.

Lectures, quizzes and assignments are littered with bugs and omissions.

A negative mark on an otherwise excellent specialisation. This lecturer has no place teaching, he made the whole subject unapproachable.

创建者 Pavel S

•Dec 13, 2019

The course has two problems:

complete lack of participation of staff in maintaining it. This leads to students giving each other incorrect advice and sharing incorrect code which passes the grader function check ( the grades are assigned automatically). The advice students give each other are frankly so wrong it is shocking.

the teacher focuses on formalised proof rather than concepts. Hence the lectures turn into lecturer applying mathematical transfomations which end in a formal argument without any intuitive understanding of the underlying subject. This course is the worst of the module with linear algebra and multivariate calculus being much better

创建者 Alan

•Aug 04, 2020

Very disappointing compared to the other courses. Recommend a complete revision of the course materials. Quizzes often had nothing to do with the preceding video. I worked through a week two quiz using the extensive notes in the discussion forum and by searching the internet. The next lecture proceeded in the same vein: the instructor failed to cover the material in video leaving me to figure out what the material was and then figure out how to find that material on the internet or in reference books. At that point, it just was not worth the time to take the course.

创建者 熊华东

•Jun 08, 2018

This course is far far far behind my expectations.The other two course in the specializition is fantastic. There is no visualization in this course, Instructor is always doing his algebra, concepts are poorly explained. I can't understand a lot of concepts in this course because of my poor math background.But why do i take ths course if i have a solid background in math? Programming assignments is not difficult but hard to complete because of vaguely clarification.Plenty of time wasted to find what should i do, its' really frustrating.

创建者 Raghav G

•Jul 13, 2020

The course is very monotonic and boring and it is quite difficult to understand much of what the extremely mathematical terms that the instructor does. I am an M.Sc. Mathematics student and even I could not understand nor enjoy more than half of the course. I would strongly advise against taking this course, however the other two courses from this specialization are good and interesting.

创建者 Horacio G D

•Jul 31, 2019

Feedback for the assignments sucks! The discussion forums don't help. I have to submit the last assignment last 6 times until it work, and I still don't know why my previous versions didn't pass. Other than that, the lectures are actually very good, but the only one worth the time is the fourth one, the other three are just the first course (Linear Algebra) all over again.

创建者 Galina F

•Jan 08, 2020

Mathematical concepts are clear, but no explanation how to apply them to python to solve machine learning ussies. But you need this for python assignments.

Scripts checking assignments work uncorrectly such a way that one can submit the same piece of working(!) code and get 0/10 and then submit the same code and get 10/10.

All in all, it's very annoying and disappointing.