Collabrative filtering lab regularisation

Course Q&A Machine Learning Specialization Unsupervised Learning, Recommenders, Reinforcement
1

In the lab the equation given is

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However, the code to implement regularization is
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Why do we not need to multiply x(i) regularization by lambda?

3

Does this mean the equation in the lab needs to be updated?
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And also in the slides.

I had to check the hints to realise that the multiplication by lambda is not included, and that is why my tests were failing

4

I’ll check on it.

Can you give a specific reference to the lab name and section of the lab, and also where it appears in the slides?

5

Yes

Lab

  • Name: C3_W2_Collaborative_RecSys_Assignment
  • Section: 4.1
  • Exercise: 1

Slides

  • Week 2: Collaborative filtering algorithm lecture (link)
  • Timestamp: 8:49
6

I’ll check on the notebook.

Note that the lecture slides are never maintained. At most they can put a pop-up between video lectures to clarify specific points.

7

That makes sense, but if you do not apply the regularization to X then the code will return incorrect cost even with lambda = 0 . The hint for regularization is incorrect / not aligned to the regularization term on the slide. Took me a while to figure out as well.

8

Hey @Balazs_Margl, and @Osama_Bsher,

I just read very carefully the parentheses in that last hint for regularization, it does implement as the equation requires. Lambda is being multiplied to both the w term and the x term. :wink: Would you mind to take a second look?

Cheers,
Raymond

1 Like
9

I see, my mistake!